MARKETING MIX

67

Calc ium al gina t e

(0 . 04 g )

was added to each

of

th e m ixtur e s . A

c

o

n_tr_{ol of phage and broth was al so p}r_{epar ed}

.

_{Phage c ount s}

(

_{dupl i c a t e} pla t e s

)

wer e done by th e so ft agar m e tho d u si ng a w i d e range o f

calc ium c onc entr a t i o n s _{in th e so f t agar .}

In th e trial s wi thout c i trat e , conc entrati ons o f cal c ium in the so ft agar _{up to a maximum of}

2 , 000

_{ppm rai s ed th e pl aqu e c oun t s ,}

and th ese f igur e s w er e som ew�at s im il ar t o th e r e sul ts wh er e c i tra t e

(o . _25%)

and al ginate were pr e s ent . I n th e trial s rih er e

c i

tra _te

( 1 %)

and al ginate wer e pr e s ent , th e high amount of c i trat e

and

th e calc ium apparently had an effec t in c au s i ng a l ow pl aque c ount or ob scuring

some

p l a qu es , a t a concentrat ion of

2 , 000

ppm cal c ium . Conc entrations of

3,000

ppm o f calc ium and above y i el d ed pl ates impo s s ibl e to c ount bo th in the abs enc e of c itra t e and in th e pr esenc e of c i tr a t e plus algina te.

Trial o f var i ou s c omnounds for cal c ium algi n a t e

Recommend ed sol vents for calc ium al ginate ar e s o d ium c i trat e ,

sodium

glyc erophat e ,

and

so d iu.1'!1 h ex:am e t.apho sphat e , and almost any

o th er sodium _{sal t provided th e c al c ium sal t of th e ac i d radicl e i s}

so lubl e.

A n _{exper im ent wa s carri e d ou t a t t e�pting to d i s solve}

0 . 04 g

quanti t ies of c a l c ium al gina t e in bro th s c ontain ing phage and

1 %

sodium ac etat e ,

1 %

sodium propionate,

1 % _sodium

sal icyl a t e ,

't

6 8

Effe c t o n Plaa ue Count o f Pr e s ence or Abs enc e o f

in Bot tom a t Var iou s Cal cium L evel s in

It was necessary to fur ther inv estigate th 9 add i t i on o f calc ium to th e medium to find the amount r equired for maximum pl aque coun t s . Al so the rol e o f phosphate i n th e � edium , and th e r eason for pr ec ip i tate formati on , r eq uir ed s tudy . Ini tially work was c onc entrated on

exp eriments loJh i ch exc luded th e use of c i trate and calc ium alginat e . Expt s

1

and 2 were carr i ed o u t b y th e two-layer m e thod.

Phospha t e was added to or omi tted from th e medium as shown in Tabl e

XXV. A range o f cal c ium conc entrations i n th e top agar l ay er was pr epar ed by adding CaC1 2 to th e m edium , c entri fug ing , and then using the cl ear m edium . For the top l ay er 2. 5 ml of agar medium , 0 . 1 ml phage, and 0 . 2 ml cul tur e w er e poured onto th e agar m edium alr eady in th e Itlate. In Exp t

2

_{no t only} was pho sphat e om i t ted from th e bot tom l ay er , but pr eviously added CaCl 2 r emoved wi th th e pr ec ipi tate any phosphate or o th er sub s tanc e in the medium wh ich form e d an

insolubl e prec ipi tat e with c al c iUtr . All phage for one exp eriment was from the same d ilu te suspension in peptone- sal t solut ion . Th e appearanc e of pl aques and m ed ia was r ecorded.

In Expt

1

it vas found tha t maximum plaque c ounts wer e s ecured a t 2 , 000- 3 , 000 ppm cal cium . In th e sec ond port ion o f thi s experimen t , wh er e phosphat e was not added to th e bottom lay er , th e added calc ium reac ted wi th a cons t i tuent of th e medium

(

phospha t e?

)

to form a precipitat e 8

In Expt 2 i t was found that there was no advantage i n treat ing the agar used for th e bo ttom l ay er w i th CaC1 2� Th is trea tment resul ted in v ery faint plaques and th er e was appar en t ly too much cal c ium for opt irnal plaque development in some c a s e s .

The above resul t s confirmed t h e need for som e c al c ium addi tion but establ i shed that fur th er experimen ts were nec es sary to fi nd b e s t

6 9

Tabl e

XXV

_{Effec t on count of}

_{or absen c e of}

In document Plan Estratégico de Mercadeo Designer Software Ltda (página 40-44)