2 MARCO TEÓRICO O CONCEPTUAL
2.3.7 RESPONSABILIDAD PATRIMONIAL
Figure 27 Effect of increasing Mg++ in incoming medium from 0.2 mM (o) to 0.4 mM (6) on OD in continuous culture of strain S-6.
spec i fic r a t e o f pro duc t ion of ent erot oxin B , TEP , deoxyribo nuc l eas e and lys o zym e was higher at the hi gher c onc entra t i on
o f l'lg++ .
An
unexpec ted findinc; was that lipase pr o duc t i onwas r e duc e d at th e higher Mg+ + c onc entrat ion . The yi e l d c ons tant was r educ e d from 1 2 . 7 t o 8 . G m g c e l l s p e r ml''i J.VJg++
when the l''"g++ in th e inc om ine; nutri ent ·vms inc r eas ed to
0 . 4 mM , s u�ges ting that a high e r intrac el l ul ar c onc entrat i on
of Mg++ had r e s ul t e d . The change in yi e l d c ons tant reported
here has als o b e en found v:i th o ther organi sms . 'f emp e s t
( 1 970 ) s t at e s that the Mg+ + , K+ and P contents o f mic ro organisms ar e known t o vary with growth rat e , and that ther e f or e the yi e l d may b e exp e c t ed t o vary with di lut i on rat e ·when the ava i l ab i l i ty o f any o f th es e s ub s t anc es i s made
t o l imit grohrth .
Lff e c t o f on in c ontinuous c u l tur e '..Jh cn the mediULJ. contained 0 . 1 l'i glucose, there wer e mark ed
trans i ent o s c i l l a t ion s in OD , entero toxin B and TEP. Th e s e
o s c i l l a t i ons \·rer e h i gh ly r e pr o duc ib l e . \-.;hen th e di l ut i o n
-1 '
r a t e was 0 . 24 h , a s t e ady s t at e w a s only achi eved a f t er
appr oximat e l y s ev en r e s iden c e
times
( 28 h ) in the pr es enc e o f gluc o s e , as c ompar ed with approximat e ly four re s idence t im e s( 1 7 h ) in the c ontr o l exp erinent wi thout gluc os e ( Fi g . 28 ) .
When the d i luti on rat e was 0 . 07 h-1 , a s t e ady s t a t e was only achi eve d aft er approximat e l y s ix r e s idenc e times ( 87 h ) when gluc o s e \vas in the m edium , as c ompared v'rith one r es i d enc e time
( 1 4
h ) in the c ontrol without gluc o s e ( Fi g . 29 ) . The addi t i on o f gluc os e al s o resul t e d in trans i ent o s c i ll a t i ons when the.l'lg++ c onc entrati on in the inc oming medium was inc r e as e d to
0 . 4 ml-1 ( Fig . 30 ) .
The mor e pro l onged o s c i l l a t i ons at the l ower dilut i on rat e s ugg e s t ed that there may b e an inhibi tory produc t o f f ermenta t i on which was pro duc ed at the end of the b atch cultur e phas e o f growth . Such an inhib i t or would b e l e s s rapidly washe d out at the l ower dilution rat e . Such end produc t inh ib i t i on was c ons i d e r e d r e s p ons ib l e for damped o s c i l lati ons ob s erved
in c ontinuous c ultur e by Yano and Koga ( 1 97 3 ) .
.