HAORONGBAM JOLDY DEVI, ELANGBAM MANITON SINGH AND YUMNAM ASHA DEVI
Abstract
Lactase (?-galactosidase) is an essential enzyme that hydrolyses lactose into glucose and galactose. Its deficiency leads to lactose intolerance, affecting nearly two-thirds of the global population. Industrially, â-galactosidase is valuable for reducing lactose content and preventing crystallization in dairy products, thereby improving sweetness and digestibility. The present study aimed to isolate and identify lactase producing microorganisms from various natural sources and evaluate their enzyme production under submerged fermentation. Milk, curd, and soil samples were collected from different locations in Bangalore and processed for microbial isolation using De Man-Rogosa-Sharpe (MRS), modified MRS, Eosin Methylenelue (EMB), and Sabouraud Dextrose agar (SDA) media. A total of 28 microbial isolates were obtained and characterized based on colony morphology, Gram staining, and biochemical tests. The isolates were screened for lactase activity using o-nitrophenyl-?-D-galactopyranoside (ONPG) assay, where the appearance of a yellow colour confirmed enzyme activity. Among the isolates, Escherichia coli, Lactobacillus sp., and Fusarium sp. were found to produce lactase enzyme. The enzyme was detected only in the cell pellet, indicating its intracellular nature. These findings suggest that the isolated bacterial and fungal strains are promising candidates for industrial-scale lactase production. Their ability to produce â-galactosidase efficiently under submerged fermentation conditions highlights their potential application in the food and pharmaceutical industries, particularly for developing lactose-free or low-lactose dairy products.