Screening and Characterization of Cold-Active β-Galactosidase Producing Psychrotrophic Enterobacter ludwigii from the Sediments of Arctic Fjord

Low-temperature-tolerant microorganisms and their cold-active enzymes could be an innovative and invaluable tool in various industrial applications. In the present study, bacterial isolates from the sediment samples of Kongsfjord, Norwegian Arctic, were screened for beta-galactosidase production. Among the isolates, KS25, KS85, KS60, and KS92 have shown good potential in beta-galactosidase production at 20 A degrees C. 16SrRNA gene sequence analysis revealed the relatedness of the isolates to Enterobacter ludwigii. The optimum growth temperature of the isolate was 25 A degrees C. The isolate exhibited good growth and enzyme production at a temperature range of 15-35 A degrees C, pH 5-10. The isolate preferred yeast extract and lactose for the maximum growth and enzyme production at conditions of pH 7.0, temperature of 25 A degrees C, and agitation speed of 100 rpm. The growth and enzyme production was stimulated by Mn2+ and Mg2+ and strongly inhibited by Zn2+, Ni2+, and Cu+. beta-Galactosidases with high specific activity at low temperatures are very beneficial in food industry to compensate the nutritional problem associated with lactose intolerance. The isolate exhibited a remarkable capability to utilize clarified whey, an industrial pollutant, for good biomass and enzyme yield and hence could be well employed in whey bioremediation.