Studies of β-Galactosidase Production and Immobilization Using Novel Bacteria Isolated from the Soil Enriched with Whey

Background: β-galactosidase is an enzyme that hydrolyzes lactose to glucose and galactose. Lactose is the major sugar present in milk and its hydrolysis makes milk fit for consumption by lactose intolerant people. Enzymatic hydrolysis of lactose is one of the most important biotechnological processes in the food industry. Thus, the continuous efforts are going on to enhance β-galactosidase production and operational stability of immobilized preparations. The present paper deals with isolation of bacteria using soil sample enriched with whey, identification of bacteria, β-galactosidase production and whole cell immobilization to evaluate the potential of isolated bacteria for industrial application. Methods: The identification of isolated bacteria was carried out using 16S r-RNA based technology. The fermentation medium was optimized using response surface design and permeabilized whole cells immobilization was carried out using gelatine-alginate gel. Results: The isolated bacterial strain was identified as Pantoea septic, which produced 2.0±0.06 fold higher β- galactosidase activity than the known bacterial strain when tested under similar experimental conditions. The fermentation medium optimized using response surface design resulted into 26.45±0.52% higher β-galactosidase activity than the nonoptimized media. Toluene treated isolated bacterial whole cells showed 4.86±1.4 fold higher β-galactosidase activity than the untreated cells with negligible enzyme leakage. The maximum activity for immobilized enzyme was obtained at pH 5.5 and temperature 60 °C. After ten consecutive cycles, immobilized whole cells displayed 80.4±2.3% enzyme activity of its initial activity. Conclusion: The isolated bacterial strain, which produced 2.0±0.06 fold higher β-galactosidase activity than the known bacterial strain when tested under similar experimental conditions prove its novelty. Secondly, the isolated bacterial strain which was identified as Pantoea septic has not been reported as β-galactosidase producing strain so far. There is a possibility that the further genetic modification of isolated bacteria may give highly active and stable β-galactosidase producing strain in comparison with the microbes being used currently at industrial level operations. In addition, the immobilized preparation has retained 80.4±2.3% enzyme activity after ten consecutive cycles. All these results strongly suggest the high potential of isolated bacteria (Pantoea septica) for industrial applications.