Effect of nitrogen sources on production of β-galactosidase from Bifidobacterium animalis Bb12 and Lactobacillus delbrueckii ssp. bulgaricus ATCC 11842 grown in whey under different culture conditions

The present study examined the effect of various nitrogen source such as yeast extract, peptone, casein hydrolysate, tryptone, ammonium sulphate and whey (control) on the growth of B. animalis Bb12 and Lactobacillus delbrueckii ssp. bulgaricus 11842 and production of β-galactosidase (β-gal) grown in deproteinized whey by these organisms. The organisms were grown in deprotenized whey (control) and that containing 3.5% of yeast extract, peptone, casein hydrolysate, tryptone, ammonium sulphate was supplemented as a nitrogen source and β-gal activity was determined using o-nitrophenyl-β-D-galactopyranoside (ONPG) as a substrate. The strains were able to utilize a wide range of nitrogen sources such as yeast extract, peptone, casein hydrolysate, tryptone and ammonium sulphate in deproteinized whey. In general, yeast extract and peptone were found to be more suitable for β-galactosidase production. The highest level of β-gal activity at 45.69 unit/mL was produced with peptone followed by yeast extract at 43.44 unit/mL by B. animalis Bb12 and 46.6 unit/mL was produced with casein hydrolysate followed by yeast extract at 46.25 unit/mL by L. delbrueckii ssp. bulgaricus ATCC 11842. This study showed that whey medium supplemented with nitrogen sources was suitable for fermentation by B. animalis Bb12 and L. delbrueckii ssp. bulgaricus ATCC 11842 and production of β-gal.