PRODUCTION BY AND ISOLATION OF EXOPOLYSACCHARIDES FROM STREPTOCOCCUS-THERMOPHILUS GROWN IN A MILK MEDIUM AND EVIDENCE FOR THEIR GROWTH-ASSOCIATED BIOSYNTHESIS
L. Devuyst et al., PRODUCTION BY AND ISOLATION OF EXOPOLYSACCHARIDES FROM STREPTOCOCCUS-THERMOPHILUS GROWN IN A MILK MEDIUM AND EVIDENCE FOR THEIR GROWTH-ASSOCIATED BIOSYNTHESIS, Journal of applied microbiology, 84(6), 1998, pp. 1059-1068
Four Streptococcus thermophilus strains (Strep. thermophilus ETC, Stre
p. thermophilus LY03, Strep. thermophilus 480 and Strep. thermophilus
Sfi20) have been examined for their exopolysaccharide production capac
ity. All strains produced a polymer composed of the neutral sugars glu
cose and galactose, but in different ratios. It was clearly shown that
the biosynthesis of exopolysaccharides from Strep. thermophilus LY03
is growth-associated and hence displays primary metabolite kinetics. T
he monomer ratio of the exopolysaccharide synthesized did not vary thr
oughout the fermentation cycle. The production kinetics and exopolysac
charide yields were strongly dependent on the fermentation conditions.
Physical factors such as temperature, pH and oxygen tension as well a
s chemical factors (medium composition, initial lactose concentration,
carbon/nitrogen levels) were of utmost importance.