Soy whey based medium for optimized phytase activity in Saccharomyces cerevisiae MTCC 5421 and α-D-galactosidase and antibacterial activities in Lactobacillus plantarum MTCC 5422 by response surface methodology.

Soy whey based growth medium for yeast enabled the native isolate of Saccharomyces cerevisiae MTCC 5421 to produce 198 U/ml of phytase activity against that of 135 U/ml in potato dextrose broth. In the same medium for lactic acid bacteria, the isolate of Lactobacillus plantarum MTCC 5422 was able to elaborate α-D-galactosidase activity of 10.6 U/ml in comparison to 6 U/ml in Lactobacillus MRS broth. Using this formulated medium, a central composite experimental design based on 5 variables of 3 factors namely incubation temperature, pH level and incubation period showed that S. cerevisiae could produce 200 U/ml of phytase in 36 h at 30 °C and pH 3.5. Similarly, L. plantarum in 33 h at 37 °C and pH 6.6 exhibited 14.2 U/ml of α-D-galactosidase activity, whereas the antibacterial activity of 14.4 AU/ml against Bacillus cereus was evident in 42 h at 42 °C and pH 6.0. The phytase and antibacterial activity units visualized in response surface plots were more or less close to those obtained with the experimental design treatments.