Boletln Micológico Vol. 16 : 1-15 2000
TOXIGENIC FUNGI: ECOLOGY AND PREVENTION OF
I L J I . . . .
MYCOTOXIN PRODUCTION (A REVIEW)
. Ecologia
y
prevención de la producción de
sus micotoxinas (Revisión))
Cecilia L. Fulgueira & Alfredo L. Borghi
Centro de Referencia de Micología '-L,L'-.LJVil'-J, FacuJtad de Ciencias Bioquímicas y J:'ru'lrulcell1ll<~S.
Universidad Nacional de Rosario. Suipacha 531. 2000 Rosario,
FAX:+ 54-341-4804597, E-mail: cfulguei@fbioyiunr,edu.ar
Palabras FlIsariuln, Penicillillm, Alternada, micoloxinas, hongos toxicogénicos, o.,,\.nU¡::,Jd,
Key \Vords: A~rJe"RiI'lus PeJ1icilliu11l, Alternal'itl, mycotoxins, toxigenic fungi, ecology, prevention.
Las 1r"'''''''IU.'. entre ellas la
agrícul-tum, interfieren con la de las poblaciones
ftíngicas, pudiendo mayor o menor medida/os
tal/laJ'1os y la estructura de la comunidad. Si bien
mu-chas de son beneficiosas y aún
esenciales para el "p,,,,...,',, de ciertos cultivos, otras
son filopa(ógenas ylo pudiendo es/as
tÍl-limas producir que por su acción tienen
en pública,
Desde un pLinto de vista cido que las I>U1tN"R
perlenecen
se ha eslable-l1/(i5 sígníficalivas
A spergillu s,
Fusarillm, Ye~llLl~lilllll"f y Altemaria .
se disc!/ten los
princi-determinanfes así como la capacidad
para producir micoloxina$ de ciertas especies integran-tes de eSloS laxa, de esta manera a la
com-del eco toxicológico problema,
Las miCOloxinas son contaminantes nafura-les de los <l""lf::'/IH.I;'
lo tanto,
a f l r t " ' l e n / r DrlJGl,ICCIOn de sus metabolitos secundarios tóxicos, Para ello se ha diseña-do una serie de medidas temporales con el propósito de reducir esta contaminación. Entre ellas pueden desta-carse el desarrollo de de manejo integrado de cultivos y el con/rol de condiciones durante la
cose-UIl,IU..I¡;¡:¡¡rUl1l1e¡rIlU del producto final. Las solucio-nes definitivas al problema de contaminación con III1C,;U¡U.x.,IJIU',}". Y¡V"'/Wi,.."n un más prolongado para
su desarrollo e implementación, Dichas estrategias. il1-el tradicional desarrollo de resistencia a la
inva-sión fúngica en la planta hospedera, Oiros métodos
01-lernalivos, incluyen el conlrol del
crecimiento fúnglco y la manipulaciÓn J:[eJ'ff::IIC,;U des toxicogénicas, con el propósito de 1!1l'erl"ur:rlnJ'Y metabolismo de formación,
En la presente revisión, se discuten
mientos provisorios y o largo plazo tendientes a dismi-nuir o evita!' la conla1!linacíón de los aUmentos con micofoxil1as
SUlVIMARY
Human activities, such
as
with lhe dinamics of fungal poplllatfons by
high 01" 10\11 degl'ee the size and strllclure ofthe CO,/1ll11l1J1'I!V,
Even though, many funga/ species are and
essentía/ ¡or ,he developmenf of cerlaín crops, there are
other g,roups having a and lar
aloxigenic nature which lIIakes Il1em lO produce
mycotoxins Ihal, because become
relevant
in hea/lh.
From the agricultw'al poinl thal the most
genera,
The main characteristics as as
lhe abilUy lO ¡hese laxa lo
produce mycotoxins are díscussed in this review so as lO
help In the ul1,r1e}'stc.rNclme
the problems,
1\4ycotoxins are natural coniamínants
o/ foods and therefore (he
ideal stralegies control aim lo
Toxigenic fimgi: Ecology cmd prellentíon
c.
& A. Borghisecondary toxic metabolites. A series ollemporary
measures has been lo this Jn order lo
mínimize this contaminalions, sl.lch as Ihe development of
programs fo gel al1 of cultures and
¡he conl.rol 01 conditíons !he crop and sJorage of
¡he final producto Definilive soll.lliol1s lo problem 01
conJamination by toxins, rpl':l1J1J'¡i1 {or their evo/u/ion and 11711'/11!.,P7l!!:/1ll..IIW'I1. inc/ude (he usual resis/ance la
Ihe hos! plan/. Ano/her
chem;caJ 01' control
Ihe gene tic handling
01 interrupting (heir nlDfnl',r.I''':'nJ
In I/¡is ~vieu~ bolh the and long-term procedures lo minimize 01" e/se avoíd the contamination by mycoloxins are olso discussed.
I)
in nature
narure and domestic
r.l"cr~n!,1" matter provides an
(De el al .• 1996).
dimensions as well as
structures of Conslruction, wars,
recreation, and agriculture great areas of soH and
vegetation; of fungal
propagu1es and provides to fungi. Many fungi take advantage resources supplied by man. This results in the association funga! populations with
differenl human agriculture.
Nevertheless, human actívity, ina partlal \Vay, quality and quantily
oí
thls
influences man 's activitíes, anim.a1s and even man himself (Cotty el al. 1994).Onefunga1 15 the ability to produce with primary Ihe .functioning of the
Thus, through metaboliles, fungi may be
berlefi¡cial for U'U""LU''y, in man)' ways, instance, playjng
important roles in the production of cheese, antibiolics, vitamins, enzymes, and & Diener, 1987; Ellis el al., 1991). However, many fungi are also hannful
and may cause to foods or produce toxic substances such as secondary metabolites known as mycoloxins. can produced on a wide range of agricultura! comrnodities and in a diverse range of situations. Due lo their effects and lheir generally good thermal slability, Ihe presence of mycotoxins in foods and
feeds is potenlially hazardOU5 for the health
and animals and causes very important economic (Smith & Henderson, 1991; Shotwell, 1991, Lacialcová el al., 1995; Pilter., 1998). This topic has él
relevance for rural populations in developing "'l'\llnl'rI""~ for whom the hazards posed by natural coropounds can
exceed Ihe effects of manmade r"I"n",""
II)
Toxigenic
and their ecology
n.a) Toxigenic fungi in the fields and Nthough all may most of Úle researches have
grain, srnce human die! as well as throtlghout the world i5
al" 1996).
Toxigenic with crops have been, throughout history, included in two field fungi and storage fungi (MilJer, 1995). However, bOÚl
concepls are not of lhe
presence of species which are able to in both habitat.
Fungal a1tack on may already
,
occur when maturity in lbe spikes. TIte UO''''''',¡;11Il';; V,I';;<I'U""'U'" are, among others, species of Úle
1ll(J'OS'll'OI'lUnl and Fusarium. Because
field Theyare
related wirll
L\.U'Ll""'j' contents in the
necessary for Ihe activity of
Moss, 1991). The redlu~~s the values of seeds and Ihe
some toxic membolttes.
The that produce deterioration and 10ss
of quality in and are known as slorage
fungi. Fungi in stored seeds llave long been known,
as saprophytic invaders of naturally dríed
Toxigeníc jimgi: Ecology and preven/ion - C. FulglllJiro & A. Borgl1i
genera, some ofwlúch may be metaoolically active in with humidity contents as low as 13 % (Wicklow) 1994). . Where their activity is nol stopped, by low
and humidity, are capable damaging tIte seeds in a very short time periad (Agarwal &
Sinclair, 1987). In ji has been r ... n,!'\ft~'ti
that these fungi destroy more tban 30 %afUle sto red grains.
lhe quality ofthe stared may also be affected, especially tenns of vigour, germinabillty and nutritious value. A ce rtai n number ofthe
involved Conidia and sclerotia
of Ule mosl aggressive of these storage fungi are frequently
soíl (Cotty, 1989; Wicklow,
1994). Therefore, lbe original source of (he fungi in both
cases ís tIte field (Miller, the fungus-host
plant and other biologieal interactions
(reJations with oUler microorganísms, insects,
invasion before harvest. Tlle growtll oí after harvest is govemed by erop factors (nutrients, genotype
and seed physical (temperature,
humidity) and biotic factors (interactions with other presence ofinsects and inoculum ralio).
Seeds developed in a plant may therefore be exposed to an infection byfield and fungL as rhe seed loses humidity tIte maturation process, intraseminal conditions become more favorable for storage
So, al harvest a mixture of bo!b groups is assocíated with grain although field fungi are súll more isolated. are nOi limits WilJl
respect lO Ule deterioration effects produced by field fungi
and those produced by fungi (Chelkowski, 1991,
Moss, 1991).
From the agricultura! point view, it roay be
stated, to this moment, that tIle most Slgrunlcallt
me fungi belong to the Aspergiflus, Fusarium, Peni-cillium Alternaria genera (Wyatt, 1; Pittet, 1998; Sweeney & Dobson, 1999;).
n.b)
The genus
Fusarium
and
mycotoxins
genus exhibits a remarkable degree vanability in morphological, and ... " .. vE>'''''''
attributes (Logrieco el al., 1999). Some are specifically palhogenic for putrefaction in roots,
deaUt of planlules 3nd cancer in mature plant and other species are saprophytic on senescent plant matter, while there are even sorne those that cause degradation of industrial products (Smith & Moss, 1985).
Most Fusllrium are Uuoughout
world and be isolated a wide variety of samplcs, especiaUy in zones, where are considered fue most important plant patbogens (Lacey,
1990; el al., However, are found in
,... ílrt (\1", ! 00
"-'H"""."
el al., 1995; Placinta el al., 1999),A number to the genus
Fusorium are c'apable of producing secondary toxtc
metabolites (De Nijsel al., 1996) anddiffer from lhe genus Aspergiflus in lllat only a few ofthe latter produce mycotox.ins. De Nijs el al. (1996) reported Ihal, out of more
rhan 61 Fusarium 35 were to produce
some mycotoxins. TIte main groups of Fusllrium toxins
common]y in are trichothecenes,
zearalenones, and fumonisins (placinta el 1999). In addiúon, monilifonnin, beauvericin, and fusaproliferin were
also found in FU$urium cereal ears (EoUalico, 19(8).
Tlle a particular may
vary among ¡so lates ofUle same species (MiJler el al., 1991).
Production of msy rherefore be used
chemio-taxonOlnically lO ideutify FUSlIl'ium isolates as a slmin or a
variety (Ntiller el al., 1991; Lori el al .. 1992).
The are subdivided i nío four groups, with Iypes A and B representing Ule most importan!
rY\"'l'YIh",,.., The synlhesis ofthe LWO
appears to be characteristic for fI particular Fusarium (placinla el al, 1999). F. sporotrichioides, F. poae
and E equiseti are considered lO be the mos! important species producers of tricholhecenes of Group A (funda-mentalIy T-2 and HT -2 1oxios, diaceto~1'scirpenol lleosolaniol NS). Production of Group B tricholhecenes
(deo:\:ynivalenol DON, 3-AcDON, nÍvalenol NIV fusarenon-X FUS-X) ia generally assocíated wilh F. gramiwwrum, F. culmortlm and F. croookwellense (also ze.lIalenone producers) (WHO 1990, Lori el al., 1992; Miller,
1995). F. graminearum, F. culmorum and F. croook-wellel1se cereaUs (Coake) Sacc.)also vary in pathogenicily. F. gram¡l1ellrwII is regarded as lhe mosl virulenl, although all three can
Wheat, corn and barley seem to be Ihe grajos t:bat are mesHy affected by tbese and crops
t\vo tlúrds ofthe world proouction Contaminatíon with Úlese FlJstlrtum toxins on rye, oat5 and triticale llave also becn reported (Chelkowski, MiHer, 1995). Conlamination Tricho-thecene-producing FuslIrium spp. are destructive attack a wide range ofplant species, Trichothecenes appear to be examples offungal Ulat as virulencefaclors without strong
host se1ectivity (Desjardins el al., 1996b; &
Hohn, 1997; 1998).
F. vericillioitles moniliforme)
is a
as maize and its
metabolísm includes the prod uction of at least Ulree
myco-toxius, fumomsius, moniliformin 8nd fusarin C (Abbas el al., ] 993; Wicklow, 1994; Miller, 1995;
Toxígenic fimgí: Ecology and preven/ion - C. Frtlglleira &: A. Borghl
widespread and a number of other oC Fusarium,
including E proliferatllm, E anthophilum, F. dlomilli, E napiforme and E nygamai, were able to produce it (Nelson
el 1992; Moss, 1998). The (FE" and are aIso structural congeners oC eertain loxins
Alternarla alterntIta (Chen el al.. 1992;
Plaeinla el al., It is also that fumonisins might have an ituportant role in tIte pathology of F.
verticillioides on corn (Nelson er al., 1993; Desjardins & Hohn, 1997). Olher studies indieate a probable ,,,,"'v ... 'u
between fumonisins production and high levels ofvirulence
on com, tomato and other buds el ni.,
19(5).
Uc) The gel1l1S Aspergillus and mycotoxins
The genus Aspergillus bas a high Ul'-,LalJU., ....
a great lO disperse conidia, and many Í!s SD(~CH~S are capable developing at low values of water activity
(a.).
Tlúsfact allows fuern to grow in a \Vide mnge natural substrata and climatic condítions, and to be associated with deterioration of that are toodry to be attacked by other (Gourarna &
Bullerman,
1995b). theAspeTgillus speciesconunonlyaffect pmducts and as wood,
leaUler, tex"1ile fíbres, kerosene, paínts, plasues, rubber,
cement and & Moss
Gourama & Bullennan, 1995b). Sorne Aspergillus
~pecies
are used in lhe manufacture and used (he food industry. Thus Aspergillus orywe has been
used in the , an
in Ihe manufacture of oriental fermenled foods. Aspergilllls niger has been used the productíon of
Though mosl of aspergilli are esseotia!ly
sapro-phytic, may be toxigenic
patho-genic for men and animals (Gourama & Eullerman, 1995b). Aspergillus oclfrllceoJls A. lIluttJceus) is presenl in soil, and vegetables and in the process . of decomposition. This species aod other related ones, as
weH as Penicillium verruCosum afld Penicillium
cyclopium (belong to P.aurtmtiogriseum/verrucosum
complex) a group of structurally related
lmown as ochratoxins (prelusky el (994). TIle most important in the ochratoxín has been isolated from a wide variety of plaot products, cheese aod tissues of animals tJmt had eaLen feed, tJlOugh phytotoxicity is not known (Fink-Gremmels el al., 1995;
& Hohn 1997). A. oclmu;eous ís also capable of producingpenicillic acid.
AspergiUus versicolor may be from
lnature eheese, cured meat or decomposing vegetables and
is capable of produciog an
intermediary in aflatoxin biosynthesis, as well as acid (ePA). Thelatter,
a Penicillium cyc/opium culture during a routine oftoxígenicfungi, be also produced by ,.hl'I,,,,,.,,,,.,1 found in agricultural products (A. versicolor, A. jlOVIlS. A.
. tamari,) or by used in the of fermented
foads (Penicilllum cflmemberlii and A. oryUle), ePA has becn to occur naturally in com, and
Aspergilllls clava/liS may be found in anima! excrernents, and decomposing matter.
oúler toxic melabolites, tlús specJes al50 produced species of Pellicillium.
The species of AspergiUus belonging 10 the Secuon Flavi W. Gams el al. group.) are
present in soU and conlarninate a wide variety of a gricult ural products in the areas, processing and distribuuon of such praduets. A. jlavlIs, A. porasiticus and A. nomius may produce aflatoxins (Gou-rama & BuUennan, 1995b; 1998). The four main naturally produced afIatoxins are BI, Bz' G
I and G~, Witll El
1) being the aflatoxin fcund al highest concentrntion in contaminated foad and
Ieee!.
TheA.
flavusstrains from non-toxic to those which produce aflatoxins B, and B2, while A. parasiticus may produce
aIlatoxins Bp GI and A. parflsi!ictls tends to be more stable in its productíon of lhan A. j10vus
&BuJlennan, 1995b).
AH aflatoxin producer are soilborne
DÚcroorganisms, but there are sorne differences in the
OCCIlrrence pattem el 01., 1987; 1989).
A.j1avus coniclia are more common in air than in soil, and are general1)' in tropical mild A.
parasífic!Js is adapted 10 wann environments such as and sub-tropical and been faund lo be associated w1th soil. A. p01'flsiticus 1S a more
contarninant A. j1avlIs
contamina les como Wicklow, has reported (1994) hal
consutule in cornfields.
Nevertheless, high concentrations of aflatoxi n a re produced as a result ofpostharvesl spoilage commodities stored under wann moist condil aod significant concenlralions may also be produced in the fleld
(payne, 1992; 1998; Placinta el al .. 1999).
Although aflatoxins have been reported to be phytotoxic,
it is still necessary lo determine true role of afIatoxins in
fungus-plant interacuon (Desjardins & Hobn 1997). Bíottansfonnation of aflatoxins B in sorne species, including humans that have consumed AFBI or AFB, contarninated io the production of aflatoxinsM¡ andM1• which areexcreled in milk and urine.
AFM
1 has been widely found in a offood products including infant fonnula, dried milk, cheese and yoghurt (Galvano 1996).Man in the production oi foods and antibíotics has used sorne species of Penicillium. P. roqueforli and
f.
camemberlii are employed in the manufacture of clteesematured by fungi while P. cJzrysogenum has I.he main source in [he perucilHn industry (Smith & Moss, 1985).
However, in moderale climate these are dominan! fungi assocíated witb {ood decay. Although they are essentially saprophytíc, sorne species show their
abilily lO certaín fmils and Thus P.
digitatum and P. ita/icum are the green and blue fungí respectively faund in cilrus fruit while P. expansum apples and R gladioli attacks bulbs, including aruans.
The genus Peniclllium many .v"'.¡¡;, ... u'"' specíes (approxímately 100) and tile range of mycotoxin
classes is much broader lhan thal otIler
genus (Sweeney & Dobson, 1998). Pitt (1991) anó Pitt &
Leistner (1991) 27 3 2 ~lJo.?Iv:l,
wlúch possess demonstrated taxicity.
As previously mentioned A 1s
produced not by A. ocnraceous bul also by P.
verrucosum and related (Raurantiogriseum/
verrucosum compre,,'. PellicilUum species primarily
produce oc}¡ratoxin in clima les while ,4,
odlTQceous
strains are
more commonIy associated WitJl warrnerclimates & Dobson, 1998).R dlrinum 1S widely distributed in tite world in
decomposing plant matter and and may
produce citrinín. Thls mycotox¡ n roay be synthesized
by P. lIemLCosum and UY-IJI"'UUvl;'"
and by P. ex.pansum (Smith & Moss, 1985; ,,, ... \1 Dobson ,1998).
P. e.xpansum, a fruit pathogen, may isolated
mainIy foom apples and pe.:1Is. It can be a producer of citrinín
asweU as patulin (McKinley & CarHon, 1991). Themajor source of patulin in lhe food supply is juice from apples
lIm~c[e;a wiili P. e..'(.paflslIm (piltet, 1998).
Raurtmtiogri-seumlverrucosum complex (including P. cycJopium and
(Lund & Frisvad, 1994; Sam-son et 1995) is alro frequent in cereal and is capable of producing ePA and pCll1cillic and even penilrem A. Sorne strains of P. purpurogellum, a soil fungus prirn.arily associated with tIte
deterioration produce rubratoxins. P.
roqueforti isolated from blue clleese and from other
products ¡n cold, may produce toxin, isofu-migaclavines and roquefortine (Smilh & Mos!), 1985).
ne) Tbe genus Alternarla and its mycotoxins
The Alternarl" is ubiquitous in úle almos·
phere as well as in soíl, and in agricultura} commodities. lt includes both plant pathogenic and
saprophytic Lhat may crops in the field or
cause postl1arvest decay of plan! produels in storage (Bonalico & Logrieco, 1998), Sorne may often grow
fimgi: Ec%gy and pNNentíon • C. FlIlg,uüra & A. Borghi
at low temperatures and may be associated With important
aarna~~e lO and vegetables transportation anó storage in refrigerllted conditions (Magan & 1985). Species of Alternaría are known to produce many metabolites, mostly phytotoxins, wh.ich play an importam role in the palhogenesis of planls. Conidia of species, in particular A. altemata aggr. are abundant
in
air, especial Iy during cerea! maturation and harvesl. They
are capable of producing toxic in
infected plants and/or in agricultural cOlmnodities, wlüch
can and and effects
in anirnaJs (BoHalico & Logrieco, 1998). Besides at least 70
melabolites can be by of
Alternaria, onIy seven major toxtns are known as possible
rood contruninants with a potcntial These
are leOtl8zonic acid (TA), alternariol (AOH), alternariol methyl ether (AME), aJtenuene and altertoxin 1, ll, snd III (ATX-I, ATX-IJ, ATX-lII). The effects of on (he production of Ulese myco-toxins have rarely been studied in detail (Bottalico &
.LJUE>'''~'''V , 1998).
It has been demonSlrated !hat AAL toxios (stmcturaJly similar to fumonisins) importan! role in the pathogenesis of ,4. olternata [ycoperslc1 on
tomato genotypes & Hobo, 1997).
nI)
Control offood contaminanon
witb mycotoxins
In thirty years a tremendous ei\l>anSI research on mycotoxins has [aken place. The
gathered during these three has introduced us 10
a new era
of multlple eS to 1off,
1979). TheyH . . . • . . . " , , . , a betler understanding of lhe biology of lhe involved fungi, lhe mechanisms that iniuale the production tJleir biosynthelic production faclors and \fonditions that determine fungal infection and coloruzalÍon of a and the type and quantity of rnycotoxin produced.
Perhaps tlle mosl important challenge today is to develop a package of control mea sures which, combined with tIle ach.ieved Irnowledge rníght help in lhe development of cultural behaviours that would help to or reduce contanúnauon to manageable levels (Widstrom,
J
996). WiUl litis aim in mind, provísional strategies aimiflg lo solve lile",,<'cPln. problem llave been proposed while control
measures intended to be definítive are being .... ,,', ... ,,"J'-'Y..
Provísionlll
m.a.l) Handling of conditions duríng the sowing and development oí tite 1)lant
ToXigenic [ungi: Ecology and preven/ion - C. FlllgueJl'o &: A. Borghf
a consequence an the the
1105t (the plant) and the environment In natural condiúons an internction -
more
complexlhan
Laboratorycondilions - the and
substrate, no matter whetl\er this association OCCUfS in a
crop, in slOred or in
any
otller of food. VariabiHty of environmental condítions is added to tl1e interaction other biologicaJ (actors, different írom theand plant which have influence on
lhei r growth and metabolismo
tllat fanner is to
culti-vate in a limited area, clima tic conelitions and lile kind of are almost firmly fixed. importance ofthe as a source
of
inoculumhas
been demonstrated (Widstrom, 1996). 1t was detennined t11at sorne plowíng tecltníques such as continuous crops tlle formation ofsclerotia on fue residues that in tllefields after harvest, turning them into an important sourceyears (Wicldow, 1994). The use of rotaUons - roulinely reoomme:nOl;(l to obtain a gooo proouction is a1so
to reduce contamination (Wilson el
al,. 1989; Widstrom, 1992). Elinúnaúon of weeds reduces
waler
conswnption and removes anfungal propagules. Processes of fertilization to obtain a good production are a150 adequate to
nation wíth mycotoxins.
The
seleclion
oI tlte appropriate seed is vitalgge:5WJns include use wÍlhout
fungi, use ofhybrids that combine bolh adaptaúon to tlle and resistance to insects tbough tlle thickness oftlie cover (Widstrom el al., 1994). It has also
aet,ecH~ tllat certain eoUon peanut tissues, under certain reaet to the fungal attack producing considerable levels of certain antifungal compounds ca11ed
phytoalexins.
are
believed todifferent on A.júJvus physiology such as to preven!
fungal or to the of CLLL,:UV,,'-l
synthesis (Santamarina el al., 1995).
The stress produced by excess water, drought,
high temperatures, malnutritionand by
rodents, bírds or insects on lhe host plant may conlribute
""5' ... u.. .. "') to theinfection with
jn the spikes, damaging grain, transporting comelia and notorlously increasing the mycotoXÍn concentration (Moss
In warm climates, conidia and sclerotia ofthe A. fll1vUS group are usually present in tile soil or on
pIants an source (Wicklow ,
1994; Widstrom, 1996). lt is generaJly lhat tIte
process of infection occurs tIle Aspergillus
propagules may attack developing flower
sugma
in or infect spikes frorn one to two weeks after U1eÍr fertilization, increasing aflatoxin accumulation throughmaturation (WidstrolTL 1996). Conidia may gerlDlllate and the germinative {ubes penetrate the tissues of developlng seeds,
oc
tlle fungus may tlrroughout rheand eventually lesions or ruptures
in tlle pericarp and move through areas of the pedícel
(Zummo,199 1). main of grain is
apparently tlle same for grain matured the field as for
grain
(Widstrom, 1996).Detailed studies of ílssociated climatic conditions have concluded tllat high temperatures and low humielity content during lhe development of some crops (COril, peanu1S, eouon, are significantly correlated to an important contamination witIt aflatoxins (Widstrom el al., 1990; Gourama & Bullerman, 1995h). Using an irrigation system, especíally duríng tbe reproductive perlod of the
plant 1987), or adapting sowing date this
critical perlod to coincide with tlle moment of mirúmum stress lack of waler could tlte stress produced bydrought (Widstrom el al., 1990).
In mild climates, afier a series rains, both ascospores macroconidia of E graminellrum and related species may infect wl1eat and
corn
withhigh
humidity.are
more susceptible tothe fj rst stages anthesis (Snijders, 1994).
temperature later an importan!
contamination witb DON may be produced, bu! ir tlle temperature drops Egl'llmillelll'Um may produce zeara-lenooe (Martín, 1993). In cases there are nol provisional SOlutiOIlS available and it [s necessary to carry out strict control to
Other fungi found in lhe soíl or on decomposing plant material, Ior
P.
verl'ucosum and A. ocllraceous, may also invade grain during development the fíelds and later proliferate in storage if conelitions arefuvourable,prooucingpenicillic A (Milier,
1995).
In na tu re a fungal interacls with
other mícroorganisms and rhe simuHaneous growth of different species usuaJly occurs on a cenain food. That
may alter lhe metabolism fungi, compete for
fue necessary substrate, produce unfavourable conditioIlS tlte forrnation of mycotoxins,
melaboHse
the producedor
even stimwateproduction
of one ormore
er al.. 1991). interactions be on biological control).
Same bíocides used in agriculture inhibít the
fonnation of others may favou(
biosynthesis. Up to now, only laboratory tests have been out (Zaika & Buchanan, 1987, Gourama & Bullerman,
1995h). tlle application of andlor
Toxigenlc frtngi: Ecology and preven/ion - C. Flllglleira & A. Borghi
tluoughou 1 the wilole life of Ule plant. Also, frequent field inspecLions could help in early delecLion of drought stress, nutritional deficiencies or damage caused by insects, birds and rodents (Widstrom, 1996). Tlus procedure may be critical to minünize the riskofan eventual conlaminalion wiUl rnycotoxins.
m
a.2) Handling of the product during harvest and storage lt is important to harvest as soon as possible once physiologica! malurity has been reache<! lo maintain the grain quality and milumize losses. Intacl graios must be separaled from foreígn materials and broken grains, and dried unlil a moisture content is attained which prevents a lalerfungal growth (L2 lo 14 %) (Gourama & Bullennan,1995b). With favourable climatic conditions (especially
temperature and humidity) graios may be dried in thefields, since artificial dryíng represents the mOSl imporlant
ex.pense of harvesL
Slorage conditions play an important role in the physicocheoúcal and microbiological quality ofproducts. Humidity levels and temperature are lhe most important faclors to be taken inlo account in lbe prolection of slored grains from fungal growth and mycotoxin production (Cbatterjee 1990; EUis el al., 1991; Widstrom, 1996).
Humidity is essentia] for fungal grawth. It has been demonstrated tbal A. flavlIs, for example, will not invade stored cereal grains and oleaginous seeds with a relative llwnidity ofless than 70 %. At this relative hwnidity, wheal humidity contelll is approximately 13 % and 7 -10 %
for products rich in oil, such as peanuts and col10n (Ellis el
al., 1991).
To control fungal growth, various studies have verified lhat lemperature should be reduced to 5 oC as soon as possible, especially in penshable products. However, LIte use of low temperalures for (he storage of agrieu Hura! products on a large scale is generally economically
unfeasible. ..
Tlle presence of insects in slored products indica-tes tllat tlle temperature and / or IIunudity have increased in sorne "hol spots" since mosl insects are not capable of living and reproducing al low levels of lmmidity and temperature. Good aeration is indispensable if one aims at keeping lhe graios cold and unifonnly dIY (Smilyh, 1990).
Conservation of products in plastic hennelic conlainers or sealed plastic folders under refrigeraled condilions may maintain the humidity, especially on rhe st\ltface, providing favourable conditions for fungal growth, thus precautions must be taken so as not to creMe a propitious environmenl for mycotoxin synthesis.
The gaseous atmosphere is another critical environrnental factor that has its influence on fungal growth. For tlle conservation of sorne foods either storage in controlled almosphere (CAS) or package in modified
almosphere (MAP) may be used (Ellis el 01., 1991).ln CAS tlle gaseous almosphere is modified to a desired level and kept at tllat level throughout tlle whole slorage. Thus CAS has been applied to control Ule grawth of A.flavlIs and the produclion of aflaloxins in peanuts stored in bulk (pill el
al., 1993) and to prevent contanúnation by insects in stored
grains (Ellis el al., 1991). MAP consists ofpacking food products in malerials with a gaseous barrier. where the gaseous environment has been changed (generally increa.sing lhe CO~ conten!) lo slo\\' down breathing, reduce Ihe microbiological growth and delay enzyroatic damage. Not many data witll respecl to the production of mycotoxins in foods packed in MAP are available yel. However, both CAS and MAP
seem
lo be natural and econonucal meUlods to control fungal growtIl as wellas
lhe production of mycoloxins in sto red products.m.b) Mcasures of definitive control
Permanent solutions to lhe problem of contaminalion of grain and oleaginous seed with mycoloxins require time for theír development and implementation. A definitive meUlodfor Ule control ofpests and diseases is based on tlle creation of resistance in the hosl plant. A second alternative to achieve a solution in tbe long run has been the imposiLion of chemicals and /or conditions 00 the flUlgus. that i!Úúbit rnycotoxin produetion. Anotller means of control is tlle use of other rnicroorganisms tllat rnighl limillhe growth ofloxigenic fungi by differenl mechanisms. A last alternative might be genetic manipulation of Ule fungus to cause an interruption in its ability to produce mycotoxins (Widstrom, 1996).
m
b.l) Devclopment of rcsistant bybridsFrom
the beginning most of lhe research has been focused 00 obtaining plants resistant to aflatoxin conlami-nation (Zubee, 1977). A reliable identificalion of the type of plants resistant lo fungal invasion \Vas not possible until a uniform inocu lation could be ac hieved under field conditions. It was also necessary to determine lhe most appropriate moment and melhod for inoculation and the Lime and way in which Ule samples had lo be taken in developed grains (Widstrom, 1996). The subsequent screening revealed tllal even if evaluatíon and selection were difficull, tlle processes ofinfection and contamination would be under gene tic control (Zuber & Lillehoj, 1979). Various importanl sources of genetic resistance llave recentlybeenidentified(Scott&ZlUlUno 1988; Campbell elEcology and preven/ion - C. F1Ilgueira & Á.
mb.2) IntemJption oftbe toxin production
In terru pt ion of (he mycotoxin production may be also achieved by controlling the
microenvironment where these fungi develop
oc
by metllods of chemical or biological control.Mb.2.a) Chemical intencrcnce in the production oftoxms A number of compounds that inhlbit or
grOwtll and I
oc the fonnation of toxins have
tested. Mosl of have been evaluated in products and consequently they have not been sug;ge5¡tedfor developing plants. Among are potassium metabisulfite, bicarbonate, different phosphate compounds snd alkenals el al., 19&9; Montville
el al., 1988~ Zeringue, 1991). However, none recommended as an
a commercial point ofview.
Compounds from dlfferent biological sources, as volatile ex1racls and compounds
indica leaves, spices and their oils, have also been as inhibitors of mycoloxin production
McConnick ,1988; Chalterjee. 1990~ Ranjan el al., & Bhatnager, 1994).
Finally, compounds isolated from com
also becn reported as having Ihniting activity against A. flavus production
(Neurece
& Godshall,1;
Neurece, 1992). E..';periments by Brown et al. (1993), provide that resistance 10 af1atox.in con1arni nat ion is related to metabolic activities in the living com embryo.Interferencc or biological control
ln Nature, fungi not only imeract wirIl lhe
"v:iÚl many microorganisms ~,,;¡;:,v'.H
zone. In order to succeed, the
u.;.;;>'",a;;>'",,,, using biologícal strategies
the pathogen population or ... "-,,, ... ,,'F> through beneficiar lnicroorganisms (Gabriel & Scol1, 1995). It is desiderable, in general, tbat
organisms
are
already part oHileof exotic environment. Tbe biological control
cl\:posure to
potential1y toxic peslicides,rhe smface of marketed products and in ", .... ",."","',,, .... ,,'" lower risk of eovironmen tal pollution than c.mmuc¡u
as well as a more profitable cost-benefit
... ,,'c ... ,,'u, 1992; Gloer ,1995),
Inlerest in new biological methods has increased in recent years, supported by thal point out lbat those antagonistic antimicrobial metabolites rnight acl as to control toxigenic fungal growth (SchilUnger
tests of intraspecies or ínterspecif competition llave been made. The first type of biocon
control involves lhe use of non-toxigeníc slrail isolaled lhe same habitat where lhe toxigenic stmil eitller as agents of growtlllimitation and / or é ofmyCOloxin production. Thestrain stabilily is fundamental criterium in the selection of this type ( biocontroL (CoUy, 1990). In tJlese tests, carried out i
El''-'''"U'''''''"''''''''' or in lhe fields, aloxigenic straíns (l1igl11 were inocu1ated together wíth 111 loxigenic strains in corn ear (Brown Cott
or coHon bolls (Cott)', 1990), or roots í (Chourasia & Sinha, 1994), or added I
cereals or oleaginous plants were growin 1992; Cotty,1994; Dorner elat., 1998:
1999), In most cases (he atoxigenic strain diminish~
m'j"col.oXltnCOnlamination of Ule seeds when it was taneoulsly with, OI previously lO the loxigeníc slrai
Brown & COlty, 1991; Dorner el al,. 199: 11I'\11,r!l<!'H\ & Sinha, 1994; COI1y, 1994). However, diñerena were found in the ability of atoxigenic strains to preve] productioll, especially of aflatoxins (Colly •
JjJ~ltnager, 1994; Domer el al,. 1998; Domer et al .. 1999 indicaled thal a higher degree of control
when plols or fields \Vere relrealed wil biocontrol agenls in subsequent years (Domer el al .. 1998
Interspecies competition tests, in wlúch of Aspergillus, Fusllrium or Pellicillium we confronted in lhe laboratory, in greenhouses or in lhe fiel,
wítb
biocompetitive agents (a1so isolated fro:the same ec 01 ogi ca I nicheas tlle organism lO be controlled more variable results (Misaghi el a/., them different species of filamentous
runo
(Aspergillus AspergilJus lIur¡comus, PenicUlill. sp., Fusarium sp., TricJzodemw sp., Rlrizopusel 1985; Devi & Po)asa, 1987;
el
a yeast
1996) could inhibit lhe UI;:;Vl;:;lU¡Jn,¡;:;!
andlorthe production or fungaI pattems of colonization in vilYO
1998a,MarinetaJ., efa/., l
In greenhouse and field tests a significa decrease in infection of corn wilh A. fltlvus I tIle subsequent productíon of afIatoxins, to ",,,",,,u.¡;nn
with F. moniJiforme was reported (Wícklow el al., 198 Widslrom et al" 1995). The reduction in tlle m" .. "",... .... production by compelition between Aspergillus al Fusarillm sp. was smaller in field than in
(Ehrlich el al., 1985; Widstrom el al .. 1995) . .l:Se!51Qf~,
also been suggested Ulat the use
Toxigenic fimgi: and preventiol1 • C. FulgllelTa & A. Borghí
appropriate time means of infeclion are not the sarue for both fungi (Widstrom el al .• 1995).
lhe last years Ule objective differenl investigations was to study influence exerled by (otherfungi and groWlh and production of mycoloxins by Inhibítion of growth of A. flavus and A. parositicus was produced by metabolites of Rhiwpus microspol'US, R. orrhiZUfi and Neufospora sitophila (Nout, 1989; Lanciotti & Guerzoni ,1993; Noul, t 995). Similar effects were on Penicillium I'oquiforti byvolatile antagorustic compounds of Pichia anoma/a (Bjomberg
&
1993). Substances by other
(A. niger I A. oryzue and A. tml1arif) also inb.ibiled the
A.flIIVIIS,
A.
odlraceOlls and mycotoxin produclion (Shanla &Rati ,1990; Shanta el aL, 1990; Paster e/al., 1992, Sardjonoe/ 1992).Similarly, there have been altempts at biocontrolling LV""'¡:'vLU,",
lactie acid bacteria (LAB) been tested. In the majority ofreports il was postulated that the cause oft11is inJ1ibition was lhe action a metabolite in the cullure supernatants of lacüe bacteria (Gourama & Bullennan , 199511). It was reported that the effect of two strains of lacüe bacleria (Lae/oeoceus laetis and Streptococcus
lermophílus), with antifungal activity A.
parasiticust A.fumigatus and Rhizopus sp. The activity
was by a compound probably of polypeptide
nature since activity 'was destroyed by the acLion of
proleolytie enzymes (pronase E and el al.,
1990; Batish el 1991). Tbe culture supematant oí a
mixtureof Laclobacillus tlle production
oí by A. paras;ticlIs also reducing tlle (Gourama & Bullerman, 1995c). Tll.isinhibition \Vas
nfODalJi}V due to a of molecular mass > 6000 D. GoUltamll & BullemlaI1, (1995a). Karutnamtne el al .. (1990) reponed Lactobacillus spp. strains tOlally ... ,""" úle conidial germinaüon of aflatoxlgenic fungi.
COllnpOUfl(lS produced by Lactobacíllus spp. only
inllllblted the biosyntllesis of aflatoxins and by A.
PU1Ui>/Uf,.;I¡-> (Karutnaratne el 1990) and \Vere lO be
¡;eIl!lolhlJf!.to lh~ aclion of proleolytic enzymes (trypsín and .r.tl1il1'IV¡l1'VI1~m and ofheat (Gourmna & Bullennan
TIle antlmicrobial aclivity of other among species of Aspergillus, FustlriunI and Pelrici,Uiu.rIl was sludied (Moto mura & Hirooka, 1996). ú\em strains Bacil/us subtilis produced
sut,slan~~s which suppressed tlle growlh of tox.igenic A. pal'aSltícl<JS and A. {ltlVilS and blocked lhe of aflatoxins (Kimura & Hirano, 0[10 & Kimura, ] 991).
melaboli tes hud peptide cllll.raClerístics (Ono Kimura, 1991). In other Cc'lses, cenain slrains of B.
~"" ... y, lhe developmentof Fusarillnt
verticillioitles,
A, parasiticus
and Penicillillm exparlsum (Motomura & Hirooka, 1996). Another bacterial ident.ified as Pseudomonos completely inJübÍled A. fl(J\}uS growth in synthetic media and IheY<UUUE,'" produced in cotton bolls by Ihis fungus. This was Ibe firsr report of an antagonistic bacterium capable of
""'eH"""' ... thé by a fungus on a
plant in tl1e fields (Misaghi el al.. 1995).
oI the
Streptomyces genus are very abundant in soH and they are included in tl1ethe main of bioactive compounds and
extracellular enzymes. Their effeetiveness has been
demonstraled bacteria, some and
nematodes (Dicklow et 1993; Coelho et al., 1995;Trejo-Estrada et al .• 1998). Subslances produced by Slreptomyces spp. strail1s !hat could inlúbit growtll oí toxigenic fungi or tllcir mycotoxin production are very A Streptomyces
sp. straín produced a new compound t11at inhibits lhe
synthesis of aflatoxín B I by A. parasiticus (Ono el al.,
1997). This compound, a polyalcohol of 63 carbon atoms called aflaslatin A, díd not present on tlle fungal development.
As part of a screening of Slreplomyces strains isolaled from soU of cereal crop, a slIain wilh activity 1nhibitíng conidia germination oí A. parasiticus (aflatoxin producer), Fusariut1f gramineuFIII1I (deoxynivalenol fiÍwlenol producer) and Fusariul1I tricil1ctum (f -2 and HT-2 loxins producer) was selected. This was due (o the
presence of antifungal substances (Borghi el 19&8; el 1989; el al .. 1992). In
ca.rried out on developing wheat (in greenllouse) it was determined tIla! tlle Slreptomyces sp. straio stopped
fungal and ils decrease weighl of
lhe wheat grains caused by F. graminearum and
mycotoxin producLion el 1992, Fulgueira el
al., 1996; Fulgueira, 1998). Subsequent studies demon-strated ,thal the inhibiting activity was to proteolytic enzymes (pronase and and lo !leal and lile subslance could llave a molecular mass 8 and 20 kDa. Up to now Ihe majority of experimenls on lhe control of toxigeruc fungi llave been deve10ped corn,
pel'lUUts and catton planas. and different Sl:replomyces spp.
llave been successfuUy used to decrease damage produced by palhogenic soilborne in some cereals .3nd cruciferous plants (Tahvonen el al. ,1994). These rep,resem tlle firsl corresponding to tbe
of the effect produced by toxigenic fungí wheat plants by lhe application an anragonisl slrain Slreplomyces sp.
m
b.J) Gcnetic manip ulation of the to:dgenic lungíJnfonnalion about slowly
Toxlgemc fimgí: Ecology and preven/ion - C. FlIlglleiro & A. Borghi
1979). Work on t1\e biosyothetic pathway of afla tox.i n BI began using A. pnrasiticlIs as fuogal model, developing new strategies for identifyiog genes aod pathways for different aflatoxins (Bhatnager el al., 1989; Bhalnager el al., 199]).
A \Vide rauge of AspergiUus spp. can synlhesize
a
precursor of aflatoxins, sterigmatocystin. The first step io the biosynthesis of sterigmatocystin/aflatoxins is calalyzed by a type 1 polykelide synthase (Feng & Leonard, 1995). In contrast with most polyketide synlhases that use aceta te asa
precursor, the precursor for the aflatoxinJ sterigmatocystin enzyme is hexanoale (Brobst & TOWD-send 1994). The synthase reaction product and ftrst stable intermediate in Ihe pathway is norsolorinic acid, which undergoes a complex series of modificatioos lo yield sterigmatocystio ami, fmaliy aflato:dn. Up to OOW, many ofthe genes involved in Ule sterigmatocystin biosyotlletic pathway have been cloned and their functions ideolified. Studies io Aspergilllls nüIulmrs have shown thal the gene encoding the polyketide synUlase (pksS7) is part of a gene cluster conlaining at least 25 pathway-relaled genes (Brown
el al., 1996). nlis gene el uster occupies a 60-kb region and
contains genes for regulatory faclors io addition lo a11 of the required palhway enzymes. The genetics of Ihe aflatoxin biosynU1etic paUl\vay have also been elucidated. Mapping studies indicate that all the cloned genes
invol-ved in the aflatoxin biosynthetic pathway are cootained wiUlin a 75-kb cluster located on a single chromosome in
A. flllvus and A. pnmsiticus (Trail el {l1., 1995; Yu el al.,
1995; Brown el al., 1996; Silva et (l1., 1996; Desjardins el a/. , 1997). Genetic sludies 00 aflato.'l:.in biosyothesis in A.
lIidulnns, loo to thec10ning of 17 genes responsiblefor 12 enzymatic conversions in tlle A.FJST pathways. PaUlWay-specific regulation is by a Zn (n) 2 Cys 6 DNA - binding protein Ulat regulates aflatoxin biosynthesis but there is a clea r link between development.and aflatoxi n biosynlhesis (payne & Brown 1998).
The biosynthesis of trichoUlecenes by Fusariu III
spp. proceeds from the Ilydrocarbon trichodiene Uuou,gh a complex series of steps to trichoUlecenes such as DAS, DON and T -2 toxin. Tlle details of trichothecene biosynlhesis have beeo established through experimenls with a number of FIIS(lriu11l sp. (Desjardins el a/., 1993).ln cOnlUlOn wiUl the biosynlhetic genes for aflaloxins and many other microbial antibiotics, Lricholhecene pathway genes in Fusarillm are cLosely linked and consti.tute a gene cluster (Hohn el al., 1995). At least 10 paUnvay geoes ¡nvolved in trichothecene biosynthesis have been identified wiUtin a 23-kb region of chromosomal DNA io R
sporotrichioides (Hoho el al., 1998). The cluster contains
Tri5, !he gene encoding trichodiene synUlase, which
catalyzes Ule firsl step in tricbolhecene biosynlhesis (Desjardins & Holln 1997). Recent investigations of lhe
lrichothecene patl\\",ay gene cluster have provided new informaLion concerning lhe transcriptional regulalion of pathway gene expression (Tri6) and the transport oí
pailiway products (Tri2). A lrichot1lecene resisuince gene
(Trir) has also been identified in F. sporotrichioitles.
Expression of microbial tricholhecene resislance gene j n
wheat map provides
a
means for further investigating lhe importance oftrichothooenes in FlIsarium wheat llead scab (Hohn el al., 1998).In thecaseof fumóIilsíns, their structural sim.ilari!y to Ule long chain sphingolipid bases suggesls that their biosyntbesis may be similar to sphingolipid biosynlhesis. Genelic crosses us.ing naturally occurring fumonisin production variants have identified the fumonisin biosynthetic genes in Gibberella fujikuroi (Fusl1rillm verticillioü/es). Three genes have beeo identified, fumJ,
fUI1I2 and fl/m3. These genes are linked and appear lo fonn a fumonisin biosynthetic gene cluster on chromosome 1 of Gibberellofujikui'oi (Desjardins el 01., 19960, Desjardins
& HollO 1997).
Molecular gelletic analysis of the biosynthetic pathways of other mycotoxins of Fusflrium, Aspergilllls and Pellicillium is nol very far advanced.
Much progress has been made on the molecular characlerization oflhe genes invol'ved in the biosynthesis ofvarious mycotoxins. This knowledge is useful in order to understand the organisation, regulation and expression ofthese genes, the physiological factors controllíng these processes ando the role of each mycotoxin in the plant pathogenesis.ln addition it aids improvement ofmolecular-based detection methods for rnycotoxins <lnd mycotoxigenic fimgi in tood systems. Also, these fi ndings may allow the development ofmeasl!lres for the biological control of toxigenic fungi and the development of genetically engineered resistant crop plants (Sweeney &
Dobson 1999).
Toxigeme filngi: Eeology ond preven/ion C. Ffilglleira & A. Borghl
REFERENCIAS
Abbas, H.K., Duke, S.O. & Tnnnkn, T. (1993). PhytOloxicíly of fumonisíns 8nd relaled compounds. J. Toxicol. Toxin Rev. 12: 225-252.
Aglltwnl, V.K. & Sinclnlr, J.B. (1987). Principl.:s of seed pathology Vol [-2, CRe Press, Florida.
BllSíJico, J.C. (t99S). MicoloxinllS en alimenlos. El riesgo $obr~ la mesa, Centro d~ Public8cioMS (Universidad Nacional dd lilor~I),
Sanla Fe.
Blltlsh, B.K., Rom, L. & Grover, S. (1990). SllIdies on environmenlal and nUlrilional faclors on prodllclion of alllifllngal subslauces by Lae/obaellllH aeldophillls. Royal rood Microbio!. 7: 199-206.
Blltlsh, n.K., Rnlll, L. & Grover, S. (1991). Inleraclion of
SlreproeoeclIs laeti! subsp. dlacelyll1eris DRC-I will1 Aspergillus parasiticllS and A. filllllgatlls in milk. Cul\. Dairy Prod. J. 26(1):
13-14,
Bh~tnnger, D. & McCorllllck, S.P. (1988). The inhibilory elfecl of neem (Azadiraehla indica) I~af eJ..1mcts on aflatoxin synlhesis i,)
Aspergilllls para3iticlIS. J. Am. Oil Chem. Soco 65: 1166-116B.
Bhnlmlger. D., Clevelnnd, T.E. & LUlchoj, E.B. (1989). Enzymes in lale slage of aflaloxin B, biosynlhesis: Slralegies for idenlifying pertinenl genes. Myeopl1lhologia 107: 75-83.
Bhalnnger, D., Clevelnnd, T.E. & Klngston, D.G.I. (1991).
EnzYlllological cvidence for separa le palhways for allaloxin B\ and B, bios)'nthesis. Biochen¡islry 30: 4343-4350.
Djornberg, A. & Schnurcr, J. (1993). Inhibilion of growlh of grain slorage molds in "ilro by rhe yeasl P/chia anomala (H:lIlsen)
Kurtzman. Can. J. Microbio!. 39: 623·628.
Borghl, A.L., Fulgueirn. CL. & BrnclIlenti, B .. l.C. de. (1988),
Inhibición de Flllar{lIl11 gral/llneanllll por una cepa d~ Slrep/olllyees
sp. Bol. Mico!. 4(1): 237-242.
Borghi, A.L., Fulguelrll, C.L. & Bracll[ent!. B.J.C. de. (1992). Antagonism belwe~n loxigenic fungi and a stmin of S/replolllyees
sp. Rev. Microbio!. 23(3): 194-198,
Bottalico. A. (1998), Fl/sariwlI diseas~s of cereals: Sp~cies comple); and relared myeoloxin profíles, in Europ~. 1. Plnnl Pathol. 80(2): 85-103.
Dottnllco, A. & Logrleco, A. (1998). Toxigenie Alternaría Specíes
of Econornic Imporló'lnce, In: Mycoloxins in Agrieullure and Food Safety, edited by K.K. Sinha and D. Bhalnager. Marc.:1 lRkker Ine. New York. pp: 65-108,
Brobst, S.W. & Townsend, C.A. (1994). The potential role oC
fauy aeid initiation in the biosynlhesís of lhe fungal aromatic polykelide aflaloxin B" Can. J. Chem. 72: 200-207.
Brown, RL. & Colty, p.J. (199\). Reduclion in aflatoxin cOlllenl of maize by aloxigeníc slrains of Aspergilllls flovlI'. J. Food ProL 54(8): 623-626.
Drown. R.L., Colly, P.J., Cleveland, T.E. & WidstroJll, N.W. (1993). Living m8iz~ tmbryo influences IIccumulalion of aflaloxin in maize kemels. J. Food Pro\. 56: 967-971.
llrown, D.\V., Yu, J.B., Kclkar, H.S., Femnndcs, M., Nc.sbltt, T.C., Kdl~r, N.P., Adams, T.H. & Leonard, T.J. (1996). Twenty-five coregulalo!d Ir.mscnps define a sterigmalocystin gene c1usler in
Aspergll/!lS nidlllans. Proc. NM!. AC'ld. Seó. USA 93: 1418-1422.
CampbeU, K.w., \V¡'itc, D.G. & Toman, J. (1993). SOllrces of resislanec in F, com hybrids lo car rOl cIIlIsed by Aspergilll/s jlavlIs.
Planl Dis. 77: 1169-1171.
ChnHerJce, D. (1990), Inhibilion oC rungal growlh and inf~clio\\
in maizc grains by spice oil5. ull. Appl. Microbio!. 1 \; 148-15 \.
Ch4'lkowski, J. (19B9). rormalioll of J\\ycotoxins produced by
Pl/soril/lIt in heads of wheal. Irilícnle and rye. In: Fl/sar!lI'"
mycoloxins. Taxononly and Palhogenecily, Elscvicr Science Publishus, Amslerdnru. pp. 63-84.
Chelko\Vski, J. (1991). Fungal palhogells illnn~lIcil\g eo!real seed quolity nI harvcsl. 111: Cereol Gmin, Mycoloxins, Fnngi and Quallly in Drying and Slorllgc, cdiled by 1. Chelko\\'sky. Elsevier Scicnce Publishers, Amslcrdam. pp: 53-66.
Chcn, J., Mlrocha, CJ., Xie,
w.,
Hogge, L. & Olson, D. (1992). Producl ion of Ihe \\\ycoloxi n Illlllonisin B I by A l/ernaria o/Ienlala f.sp. lycopersici. Appl. Environ. Microbiol. 58: 392B-3931.Choudhary, A.K. (1992). [nflllence of microbial co-inhabilanls
011 al1atoxin synlhtsis of Asperglllus flal'l/J on moiz~ keme!. Lel!. Appl. Microbio\. 14: 143-)47.
Chourasill, H.K. & Slnha, RK. (1994). POlenliaJ of Ihe biological conlrol of aflatoxin conlaminnlion in devtloping peanut (Arachuf hypogaea L.) by oroxigenic slrains oC AspergillllS flal'I/$. J, Pood Sci. T~c1l1lol. 31 (5): 362-366.
CacillO. R.R.R, Lopes, A., dc Alevcdo Soares Semcdo, L.T. & Slcele da erUt, F. (1995). Culturo! filtr3lcs oC AClinolllyee/es isolal~d from tropical soíls inhibir Trypnnosolllo enlzi replication in vi/ro. Re .... Microbio!. 26(4): 307-313.
Cook, RJ. & Baker, K.F. (1983). N~lurc alld Praclice oC Biological Conlrol of PIHnl Palhogens, SI, Paul. American Phylopalhological
Soci~ly, SI hu! MN.
Cotty, P.J. (1989). Vinlleuce ~nd cultural characlerislics of l\Vo
.4sperglllllS f1nvlIs slrains p31hogtllic on collon. Phytopathology 79: 80S·814.
Cotty, P.J. (1990). Effecls of ~Ioxig"-nic strains oC Aspergíll/l$ (l.av"s on anatoxin conlaminalion of do!vtlopillg coHonseed. Planl Dis. March 1990: 233-235.
Colty, P.J. (1994), ["fluence of tidd app[ícnlion of an aloxigellic
strain of AspergillllS flavIls 011 lhe populaliol\s of Aspergillus jla"l/s
infccling cOIIOII bolls and 011 lht analoxin eonlenl of collonseed. Phy1opalhology 84(11): 1270-1277.
Co/ty, r.J. & fiha(nagcr, D. (1994). Varinbilily among atoxigenic
Asperglllus flal'lIs slrains in abi!il)' lO pr~venl afhloxin cOlllaminnlion nnd prodllclion of aflaloxin biosynrhetic pathw:ly cnzymes. AppL Enviran. Microbio!. 60: 2248-2251.
CoUy, P.J., Boyman, P., Egcl, D.S. & E[ias, K-S. (1994). Agrieullllre, "flaloxins and Aspergilllls, In: The gelll\s A~pergilllls,
Toxigenlc Ecology and prevenrion C. FlIlgueira & A. Borghl
Cuero, R., SmiUl, J.E. & J. (1988). formíllion
by Aspergillus flmms and Frlsarium gramlneanllll in irradial.:d maize
grains in Ihe presence of olher J. Food Pro!. 51: 452-4S6.
Dl1vlell, N.D. & Dlen.er, U.L. (1987). Food nnd reverage mycQlogy.
"dítcd by L.R.. Beuchat, Van Noslrand, Reinhold, New York, pp. 517-538.
De Nijs, M., Rombouts, F. & Notel'lllím, S. S. (1996), Fusarílwl molds lInd Iheif mycoloxins. J. Food Sal'.!ly 16: 15-58.
Desjardíns, A. E. & Hoho, T.M. (1997). Mycolo;.;in¡¡ in planl
pllthogenesis. Mol. Planl . Microbe IIlI<:racl. 10(2): 147-151.
Desjardins, A.E., Hohn, T.M. & McCol'lnick, S.P. (1993).
Trichothecene biosynlhesis in FlIsaríllw: Cllemislry, geU<:lics, and
signiflcanc.:. Microbiol. Rev . .57: 214·212.
Dcsjardins, A.E., PlaUncr, R.D., Nl.'lsOIl, T.C. & Lesllc, J.F.
(1995). Gellelics analysis of Cumonisin productiol1 óll1d "iru!i!lIc<l of
Gíbberella maling populalion A (FIIJarmm lIIonilíforme)
011 maize (Zea mays) seedlings. AppL Enviren. MicrolJiol. 61: 79
86.
Desjnrdins, A.E., PbUner, R..D. & Proclor, RII. (1996). Linkagc
amollg genes responsible ror fumollisin biosynlhesís in Gibere.lla {i¡Jlkllroi popullltion. AppL Enviran. Microbio!. 62: 2.5 71-1576.
Desjllrdins, A.E., Proctor, R.H., Boll, G., McCormlck., S.P.,
Shaner, G., BuechIcy, G. & Honh, T.M. (1996 b). Redllced
v,rulence of trichothecene-non producíng mula¡Hs of Gibberella zene in wheat field leslS. Mol. Planl-MicroJ.:¡<i lnt.:rac1. 9: 715·781.
Desjlll'diJl.'l, A.E., Plattuer, R.D. &. N"ll!I.on, P.E. (1997).
Produclion of fumonisin. B, 1I11d monílifomlin lJy Giberello Jiljlkllroí
from rice from varíollS ~rens. Appl. Environ. Microbiol.
63: 1838-1842.
Devl, G.R. & POlasll, H. (1987). lnl~rferellce in tOXtll produclion among Aspergllllls J. Slored Prod. R.:s. 23.
149-ISO.
Dfddow, M.O., Acosta, N. &. Zuckcrlllfln, D.M. (1 993}. A novel
SlrBplomyceE species fer conlrolling plant-parasilic nematodes. J. Ch<lm. Eco!. 1.59-173.
Dltner, U.L., Cole, R.J. & Hm, R.A. ( of al1aloxin formalion by flavlIs. Ann. Rev. Phy1opalhoL
:25: 249-170.
Dorner, J.'V., Cole, R.J., Snlldcrs, T.H. &. Blanken!lhlp, P.D.
(1989). lnlerrelationship of kernel water ¡¡ctivity, soil lemperature,
malurity, aud phytoalexin produclion in preharv~sl afhtoxin
contamillatioll of droughl stresscd peanuls. Mycopalhologia 10.5:
1I7-128.
Dome!', J.W.; Cole, R.J. &. Dlnnke.sJ\lp, P.D. (1992). Use of a
biocornpetitive agenl to control preharvest ailatoxin in drought s1nssed peanuls. J. Fooo Prol. 55(11): 8&&-892.
Domer, J.W., Cole, R.J. & Blllnkenship, P.D. (199&). Eff~cl of
inoculu01 rate of biological c~lIlrol ag.:uts 011 prcllllrveSI :aflato;,:in conlamina1iOll of peanuls. Biol. Control. 12(3): 171-176.
Doruer, J.W., Coleo R.J. & Wicklow, D.T. (1999). AO¡\(oxin
reduction in corn through field Food ProL 62(6): 650-656.
of eompetilive
nlll
Ehrlich, K., Ciegler, A., Klich, M. & Lee, L. (1985). f,
compelilion llnd rnycotoxin produciíQIl 011 corno Experiel1\Í. 691-693.
EUis, \V.O., SmHh, J.P., Simpson, B.K. & Ohlhnrn, J.H. (1
AflO¡OXillS in food: occurrellce, biosylllh':SIS, elTecls 01\ org~ll
deloc!ion :md m.:thods of control. Cril. Rev. Food Sei, Nutr. ~
403-439.
Feng. G.H. nnd Leonard, T.J. (1 Characterizalion o
poliketidc synlhase gene (pksU) required for allaloxin
¡ti Aspergllllls parasíflclls, J. Bacteriol. ¡ 77' 6246-62.54.
Fink·Gremmcls, J., llloO\, M.J., Woulcrscn VGn Nijn:lI
F.M.A .• Jnlm. A .• de Groene, E.M. & Horbnch, G.J.M.J. (1
Biotrallsfomlalioll proe.:sses in ¡he of ochraloxicosi: Molecular Approeches in Food SaCely; ediled M. Ekl\llld, Ri.:!wrd & K Mis~. Alaken Foli Collins.CO. pp. 107-121.
C.L. (1998). Comportamiento de hongos toxicoge
ell el i1COSistellla sudo. Ph.D. Ihcsis, Universidad Nacional de Ro Rosario. Argenlina.
Fulgueira, C.L., norghl, A.L. & BNu::IlJcntí, B.J.C. d". (I~
Inhibición de A!!.pergílillS pomsiliclIs NRRL 2999 por una ce¡
Sll'eplomyces sp. Rev. Microbiol. 20(2): 21.5-2 ¡ 9.
FulguClrll, C. L., Borghl, A. L" GaUuso, M.A., Gattuso,
Brll¡::úcl1li. o.J.C. de. (1991). Interacción de hongos to;-¡icogé
con Ulla cepa de Slreptomyces sobre el desarrollo de plantas de
Bol. Micol. 7(1·2): 7-12.
Fulgucir1'l, C.L., norghi, A.L., GaUuso, M.A. & Di Saph
(19$16), Effects of Ihe inf<!.clion of (Q)(igellic SlreplOIllj'ces sirllin on wheat
142.
Gabriel, C.K. & Coo!;., R.J. (1990). Biological control of i
palhogillls, American Phy1oplllhological Soci~ly, SI Palll MN
Gnlyll.l1o, F., Galofaro, V. & Galvano, G. (1996). Occurrenc¡
stability of aflaloxin M 1 in milk and milk A wold
review. J. Food Prol. 59: 1079-1090.
Gams,W.; Chrlsll'nsen, M.; Onions. A.H.; Pill,J.L; San
R.A. (1985) Infrageneric tu XII oC .4spergíllm. In : R. Sams(
J,Piu (Eds.) Advlmccs in P(!Ilicillillnl and Aspllrgillus SyslelU. Nato ASl Series, Series A: Lífe Sciences Vol 102.. Plenum F N.York, pp.55-61
Gloer, J.B. (1995). Th<l chemislry of fungal
defense. CSII. J. &t. SI265-S1274.
Gourams, H. & Bullerman, L.B. (19950). Anrimycotic
anliaflatoxigenic effecl of laclie acid bacteria: A review. J ..
Prol. S8(ll): 1275-1280.
GaUTama, H. & Bullerman, L.D. (1995 b). A spergí11liS fI
and Aspergil/¡¡s parasiticus: aflalol\igoenic of conc:oern in I and feeds. A review. 1. Foed Prol. .58( 12): 1395·1404.
Goumnm, H. &. Bullermnn, L.B. (
lmd afla(o.~in prodllclion of Asperglllus
[Ilhibition of gr
Tox'gemc fitngi: Ecology and preven(jon
c.
&A.specitlS, J. Food ProL 58(11): 1249-1256.
Gourama, 11, & II u II enll 1111. L.B. (1997). Anli-analoxigtnic nclÍvily of Laclobacill1l5 casef pselldoplanlarum. Inl. J. Food ¡"HcrohíoL 34(2): 1J1·143.
1l0hll, T.i\'I .• Dcsjlll'dins, A.E., McCormlck, S.P. & Proclo!", R.
(1995), of Irícholheccnes, genelic Ilnd molecular
asp~cls. In: l\Jolccu lar Approaches lo Food edil~d by :\1. Eklund, J.L Richard & K. Mise, AJaken, Fort CollillS. CQ, pp. 239· 24S,
Hohn, T.i\r.. l\JcCormick, S.P" Ale:l:onder, N.J., Dcsjnrdíns, A. E. & l' ro ct o 1'. R.n. (1998) Funclion ano bíosynlhesis of
Irícholh~cellCs produced by Fllsal'ium species. Mol. Gen.
Host-spedlic To:->. Planl Oís. 13 PO: 17-24.
IIudson, ILJ. (1986). Edward Amold. LondClJ).
Joncs. H..K. (l987). The inflllence ol' cultural praclic.es on th.: d¿velopm~nl of ¡Úhloxin in fleJd maize, In: A1lalox:m
in maíz<: . .:dit~d by M.S. Zuher, E,S, Llllehoj & S.L. Renfro,
CI1vIMYT, lvI~xico. pp. 136-144,
KnrUlnllratnc, A., Wczen bcrg, E. & llullcTlUan. L.1l. (1990).
Inllibilion al moJd growth lllld al1aloxin produc¡ion by LaclobaciUlIs
spp. J. Food Prol. 53: 230-236.
KimuI'í\, N. & Ilinmo, S. (\ 988). IlIhibitory slrain of Bacillus SlIb¡i!is for growlh Ilnd af1atol!in-pmdm:lioll ol'
Agríe. BioL Chelll. 52: 1173-1179.
Kozakicwicz, Z. (1989). Aspergilllls
Mycol. 161: 1-18,
011 slon::d produclS.
L:lce~ .. J. (1990). 1\'lycoloxins in UK cereals and their conlrol.
Asp~C¡8, AppL Siol. 25: 395-405.
Lnelnkovil, A., Vlll'gová, M. & Laciak, V. (lS>9S). SOIllC mycoloxins. tausíng heallh in l'arm anímals.. Siol. Brnl.
50(3): 293-295.
Landoltl, R. & Gucrzonl, M.E. (1993). lnhibition of Aspel'gilllls
f1avru by \lolatile metabolites of arrhiZII$, Food Microbio!.
lO: 367-377.
""""1:"''', W., SfenwJng. JI., Sogn. L. & Mo. E. GroWlh moulds and productiol\ of mycotoxins in wheal during drying and s1orage, Soil Planl Sci. 43: 32-37.
e.J., Molhu, R.A., Walke .... H.W., Kraft, A.A. & Stnhr,
R.M. (l989) 11lllibitíon of mold gTow1h ¡¡nd mycolo.~in
in corn IrelllM wilh J, Food Prol. 52:
329-336,
LII2I'llee,O, A., AHomnrc, C., Mulé, G. & Moretli, A. (1999). Recent Res. De\lel. MicrobioL 3: 135-145.
Lori, G.A., C3l'rnn:zn, M.R., Vlohllltc, A., Rluo, 1. & Alippi,
H.E. F¡¡saritm¡ spp, en trigo, capacidad loxicogéllicll y
qUimlioll1lxo.nolnia de las .:epas aisladas en la Argenlína, AI>1rCII10l1l," 12: 459-467.
Lund ,V. &. Frls\'ad,J.C. (1994). Chemolnxol1omy 01' Penicillilllll
lUlrtl/uíogrisellm ¡¡ud relaled MycoL Res .98: 481-492
N. & J, (1985). TIle effect ol' WOlcr ae!illily and
lemperillu.r.: on mycQloxin produc!ion by AI/ernan/! alflilrnafa 111
culture Ilnd 00 whea! grain, In: Tricholh~ci:lles and olh.:r mycoloxlns,
cdit~d by J. Jolm Wi!.,y & SOIlS LId" Londol1.
Mnrnsas, \V.F.O. (1996), Fumonísins: hislory. world-wide
OCCUITence and ímpaCL In: Fumonígins in Foad, ooil~d by L.S. Jilckson.
1. W. DeVries &; L.B, BlIlIerman, Plenum Press, New York. pp 1·17.
Marin, S., Sanchis, V., A rllllU , F., Ramos, A.J. & Mngnn, N.
< 19980). ColonislIlioll ¡u}d compelilivcness of .·üpergillu,s ;md
Peniclfllu/lI on maizé graín in ¡he pres~nce 01' Flisariu!II
lIIonllíforme and Fllsar/llm In!. 1. Food Microbio!. 107-117.
Mllrin, S., Sanchh, V .• Ramos, A.J., Vlnfis, L ;& Mngon, N.
(1998 b). En\lironmenlal faclors, in vi Iro inlcracLÍolls, and niche o\lerlap belween F¡¡saríu/Il moni/¡jorme, FlIsarillHl prolife.ro/llm
and Fllsar/llm graminem'WII, Aspergilllls and Peme!lIIuIII 5p~cies
l'mm maiz,;: Mycol. Res. 102 (7): 831-837,
Marin, S., SUJJchis, V., RuJl, F., Ramos, A.J. & Magan, N.
(1998c), Colonisation of maíze grnin by FlIsarium momliforme nlld FlIso/'íwlI proliferollllll in Ihe presellc~ of comp.::ting l'tll,gi and
Ihclr impacl on Cumooigín producliol1, 1. Food Protecl. 61 (11):
1489·1496.
MlltlJn, R.A. (1993). Seasollal variabilily in FlIsaril/JII
ilssocialed wilh wl\eal and barley hcads. Can. J. Bol. 35: 247-251.
McKlnley, E.Ro & Corltol1, W.W (1991), Patlllill. In: Mycoloxins
llnd Phytoalex¡ns, edih!d by :R.P. Sh~rma & O. K. Salunkh.:, CRC
Press. Boca Ralon. FL, pp. 191·236,
McMlllíau, W. \v .• W¡ústrom, N. W. & Wilson, D.M. (1993).
Regíslr¡¡Jioll ol' GT-MAS:gk maíz.: gennplll.SllI. Crop Scí. 33: 8&2,
Miller, J.D. (199:5). Fungí and mycoloxins in j mp I ica ti OllS
for slored producl r;:sean::h. J. Slored Prod. Res. 31(1): 1-16.
Mille .. , J.D., Grcenludd, R., Wllng, Y. & Lu, M. (l99l).
Tricholhecene chemolypes of Ilm:c FwwríJ/1II Mycologia
83: 121-130.
Mlsnghi, LJ .• Colly, P.J. & Decinnnc, D.M. (1995). Bactcrial
llnlagonisls of Aspergilllls flCII'IIS. Bioconlrol Sci. Technol. 5: 387-391,
Montville, T.J. & Goldstein, P.I{. (l989). Sodium bicarbonate
illhibilioll ol' aflaloxigellesis in corno J. Food Prol. 5:2: 45-48, M()sg. M.O. (1991), Myco\ogy ol' cereal grnin and cereal prodllcls, In: Cereal Grain, MycoloxillS, anri Qualily in ilnd Sloragc, edilcd by J. Chelkowsky, Slsevier Sciel1ce Publíshers, Alllslerdam, pp: 23·52.
Mas!>, M.O. (199&). Recell1 sludies (}f mycotoxills. j,
Microbio!. Symp. 8uppt 84: 62S·76S,
Motomul'a, M. &; HI.-ook:I, E.Y. (l996). A.nlíl'ungal subslancc
producíng microorganisms with of applicl'!líons in Fusorillm !IloYlilifofme control. Arq. Bio!. Technol. 39(2): 471-479.
Neis/m, P.E., Plattner, R.D., ShackeIrord, D.C. & D<'sjl1rdins,
