Exopolysaccharide production by Lactobacillus delbruckii subsp bulgaricus and Streptococcus thermophilus strains under different growth conditions

Abstract

The optimal temperature, pH and incubation time for production of exopolysaccharide (EPS) by Lactobacillus delbruckii subsp. bulgaricus and Streptococcus thermophilus strains in MRS and M17 media, respectively, were determined. In all strains, the temperature and incubation time for EPS production were 45 degrees C and 18 h, respectively. At 45 degrees C, L. delbruckii subsp. bulgaricus B3 and G 12 and S. thermophilus W22 strains produced 263, 238 and 127 mg/l, respectively. At 18 h, B3, G12 and W22 strains produced 220, 152 and 120 mg/l, respectively. While the pH for highest EPS production by L. delbruckii subsp. bulgaricus strains was 6.2 (in B3 strain: 211 mg/l, in G12 strain: 175 mg/l), for highest EPS production by S. thermophilus strain it was 6.8 (114 mg/l).