Mathematical optimization of culture medium composition and cultivation conditions of Antarctic bacterial strain Pseudoalteromonas sp.22b were out to increase the yield of synthesis of cold-adapted β-galactosidase. Costs of enzyme production were approximately 40% reduced and the yield of its biosynthesis, measured as a rise in specific activity, was concomitantly enhanced 2.5 fold by using the method of factorial experiment planning coupled with gradient optimization. The evidence was provided that pure lactose can be replaced in culture medium for the growth of Pseudoalteromonas sp.22b with dried protein-free whey, without of loss of β-galactosidase biosynthesis yield.

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