LA ENSEÑANZA DE LAS UNIDADES FRASEOLÓGICAS
1.2. Las UFs: artífices de la competencia comunicativa
The contribution of QS in the spoilage process of fresh meat products stored
under aerobic refrigerated conditions, and in the biofilm formation appearing as slime
at their surfaces has been already proposed (Jay et αl., 2003). AHL production has
been detected in such products (e.g., ground beef and chicken) and appears
concomitantly with proteolytic activity (Liu et αl., 2006). A broader range of AHL
signals has been detected in aerobically chill-stored ground beef and chicken, at
pseudomonad and Enterobacteriaceae concentrations at which significant proteolytic
activity was recorded (Liu et αl., 2006).
The shelf life of fresh meats stored aerobically at refrigerated temperatures is
in the range of days, whereas the shelf life of vacuum-packed meat stored at
refrigerated temperatures is extended to weeks or months. In the last case, the
CFU g-1, respectively, thus suggesting that the spoilage is a result of an interaction
between Enterobacteriaceae andLAB (Bruhn et αl., 2004). H. alvei and Serratia spp.
have been shown to be the dominating species amongthe Enterobacteriaceae isolated
from vacuum-packedmeat. These strains are capable of producing AHLs (Gram et αl.,
1999; Ravn et αl., 2001; Bruhn et αl., 2004), while Pseudomonas isolates do not
produce detectable numbers of AHL signal molecules with the biosensor strains used
(Bruhn et αl., 2004). However, AHL prevalence in vacuum-packed meats was found
to have no significant role in the spoilage of such products (Bruhn et αl., 2004).
Pseud. fragi stains, associated with spoilage, isolated from fresh and spoiled meat
produced AI-2 signal molecules when tested using the bioluminescent biosensor V.
harveyi BB170 (Ferrocino et al., 2009). Thought, the mechanism of AI-2 production
and its possible role in spoilage processes needs further study.
Lu et αl. (2004) reported very low levels of AI-2 activity (less than one fold
induction of luminescence compared to the negative control) in meat products
although their high indigenous bacterial population loads. On the same study, certain
meat matrices were tested for inhibiting AI-2-like activity (Lu et al., 2004). Previous
findings suggest that the presence of fatty acids isolated from ground beef and poultry
meat can inhibit AI-2-based cell signalling (Widmer et al., 2007; Soni et al., 2008).
Additionally, food additives such as sodium propionate, sodium benzoate, sodium
acetate and sodium nitrate may influence AI-2 production (Lu et al., 2004).
In a recent study, Nychas et al. (2009) found that cell-free meat extract derived from spoiled minced pork meat stored aerobically at 5 and 20 °C contained QS
signals. It was also observed, that the addition of cell-free meat extract from spoiled
marcescens resulted in an extension of the lag phase of Pseud. fluorescens but not of Ser. marcescens when compared to control samples and in an increase of the
metabolic activity for both strains. The observed increase in metabolic activity was
suggested to be related to the presence of some compounds in cell-free meat extract,
including QS signal molecules (Nychas et al., 2009).
In the following table an overview of QS studies relevant to meat, meat
products and strains isolated from these food environments as reported in the
literature is summarised (Table 1.3). The classification was based on the biosensor
Table 1.3. Overview of quorum sensing (QS) studies relevant to meat, meat products and strains isolated from these food
environments based on biosensors used
Strain/Plasmid
sensor Host Based on QS system Reporter system Best responds to Good detection QS bioassay in Reference
pSB403 Broad host range LuxI/R (V. fisheri)
luxCDABE C6-3-oxo-HSL C6-HSL C8-HSL C8-3-oxo-HSL
Enterobacteriaceae strains isolated
from vacuum-packed chilled meat
Gram et al., 1999 pCF218, pCF372 A. tumefaciens WCF47 TraI/R (A. tumefaciens)
ß-galactosidase C8-3-oxo-HSL All 3-oxo-HSLs C6-HSL C8-HSL C10-HSL C12-HSL C14-HSL 3-hydroxy-C6-HSL 3-hydroxy-C6-HSL 3-hydroxy-C6-HSL
Meat extracts and isolated
Enterobacteriaceae strains from
chill-stored vacuum-packed meat
Bruhn et al., 2004
Pseudomonad and
Enterobacteriaceae isolates from
aerobically chilled-stored proteinaceous raw foods
Liu et al., 2006
Cell-free extracts from minced pork
stored aerobically at 5 and 20 °C Nychas et al., 2009
Pseud. fragi isolated from fresh and
spoiled meat
Ferrocino et
al., 2009
C. violaceum CV026 C. violaceum CviI/R (C. violaceum) Violacein production C6-HSL C4-HSL C8-HSL C6-3-oxo-HSL C8-3-oxo-HSL
Enterobacteriaceae strains isolated
from vacuum-packed chilled meat
Gram et al., 1999 Meat extracts and isolated
Enterobacteriaceae strains from
chill-stored vacuum-packed meat
Bruhn et al., 2004
Aeromonas hydrophila strains
isolated from meat
Medina- Martinez et
al., 2006 Y. enterocolitica in fresh foods
extracts
Medina- Martinez et
al., 2006
Pseudomonad and
Enterobacteriaceae isolates from
aerobically chilled-stored proteinaceous raw foods
Liu et al., 2006
Table 1.3. Continued
Strain/Plasmid
sensor Host Based on QS system Reporter system Best responds to Good detection QS screening in Reference
Cell-free extracts from minced pork
stored aerobically at 5 and 20 °C Nychas et al., 2009
Pseud. fragi isolated from fresh and
spoiled meat
Ferrocino et
al., 2009
V. harveyi BB170 V. harveyi luxN::Tn5 luxCDABE Borated AI-2 Food samples e.g. beef, chicken, turkey products (AI-2-like activity)
Lu et al., 2004 Poultry meat-derived fatty acids, as
inhibitors to AI-2
Widmer et
al., 2007
Survival and virulence gene expression of E. coli O157:H7 in the presence of AI-2 and ground beef extracts
Soni et al., 2008
Ground beef–derived fatty acids, as inhibitors to AI-2
Soni et al., 2008 Cell-free extracts from minced pork stored aerobically at 5 and 20 °C
Nychas et al., 2009
Pseud. fragi isolated from fresh and
spoiled meat Ferrocino et al., 2009 pZLR4 A. tumefaciens NT1 TraI/R (A. tumefaciens)
ß-galactosidase C8-3-oxo-HSL All 3-oxo-HSLs C6-HSL C8-HSL C10-HSL C12-HSL C14-HSL 3-hydroxy-C6-HSL 3-hydroxy-C6-HSL 3-hydroxy-C6-HSL
Meat extracts and isolated
Enterobacteriaceae strains from
chill-stored vacuum-packed meat
Bruhn et al., 2004
Aeromonas hydrophila strains
isolated from meat
Medina- Martinez et
al., 2006 Y. enterocolitica in fresh foods
extracts
Medina- Martinez et
Table 1.3. Continued
Strain/Plasmid
sensor Host Based on QS system Reporter system Best responds to Good detection QS screening in Reference
pJBA130 Broad host range LuxI/R (V. fisheri)
gfp C6-3-oxo-HSL Y. enterocolitica in fresh foods
extracts Medina- Martinez et al., 2006 pSB401 E. coli LuxI/R (V. fisheri) luxCDABE C6-3-oxo-HSL C6-HSL C8-HSL C8-3-oxo-HSL Pseudomonad and
Enterobacteriaceae isolates from
aerobically chilled-stored proteinaceous raw foods
Liu et al., 2006
Pseud. fragi isolated from fresh and
spoiled meat
Ferrocino et
al., 2009
pSB536 E. coli AhyI/R
(A. hydrophyla)
luxCDABE C4-HSL Pseudomonad and
Enterobacteriaceae isolates from
aerobically chilled-stored proteinaceous raw foods
Liu et al., 2006
Pseud. fragi isolated from fresh and
spoiled meat
Ferrocino et
al., 2009
pSB1075 E. coli LasI/R
(Pseud. aeruginosa)
luxCDABE C12-3-oxo-HSL C10-3-oxo-HSL C12-HSL
Pseudomonad and
Enterobacteriaceae isolates from
aerobically chilled-stored proteinaceous raw foods
Liu et al., 2006
Pseud. fragi isolated from fresh and
spoiled meat
Ferrocino et
al., 2009
MM32 V. harveyi luxN::cm luxS::Tn5 luxCDABE Borated AI-2 Ground beef–derived fatty acids as