Effect of yeast extract supplementation on beta-galactosidase activity of Lactobacillus delbrueckii subsp. bulgaricus 11842 grown in whey
2001
Bury, D. | Jelen, P. (University of Alberta, Edmonton (Canada). Dept. of Agricultural, Food and Nutritional Science) | Geciova, J.
Lactobacillus delbrueckii subsp. bulgaricus 11842 (LB 11842) was grown in reconstituted sweet whey supplemented with 0 to 1 % yeast extract. The beta-galactosidase activity was determined from the hydrolysis of o-nitrophenyl-beta-D-galactopyranoside (ONPG) by sonicated cultures. Shake flask cultures containing 0.2-0.8 % yeast extract gave 2.5 times higher beta-galactosidase activity than LB 11842 grown in sole (intact) whey. When supplementation with 1 % yeast extract resulted even in a threefold increase of beta-galactosidase activity. The rate of acid production increased with the addition of yeast extract, while the increase in the total cell count with increasing amount of yeast extract was slight. A maximum beta-galactosidase activity of 1.08 +/- 0.15 micromol ONP released per min per mL of culture was obtained using a whey based growth medium supplemented with 1 % yeast extract.
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