Study of physical and cultural parameters on the bacteriocins produced by lactic acid bacteria isolated from traditional Indian fermented foods.

摘要

Lactic acid bacteria (LAB) predominate in the microflora of fermented foods. They produce metabolites that inhibit growth of foodborne pathogens and spoilage microorganisms. This study sought to isolate and identify LAB from traditional Indian fermented foods and determine the properties of the bacteriocins produced by them. 7 isolates of bacteriocin-producing LAB were obtained from curd, dosa batter and idli batter, and were all identified as species of Lactobacillus. The culture supernatants of the 7 isolates were evaluated for their antimicrobial activity against pathogens, such as Staphylococcus aureus and Pseudomonas sp. The stability of the bacteriocins was tested at different temp. and pH, in the presence of bile salts such as sodium deoxycholate and during storage period at 4 degrees C. Diam. of the inhibitory zones ranged between 9 and 12 mm for S. aureus, but no effects on Pseudomonas were observed. The bacteriocins produced by the isolates were stable at 30-80 degrees C and over a pH range of 2-10, with highest activity at pH 6. The bacteriocins were stable at different bile salt concn. and remained active even after a storage period of 30 days at 4 degrees C. SDS-PAGE analysis of the partially purified bacteriocins indicated that their mol. wt. were in the range 16.5-48 kDa. These bacteriocins may have potential uses as food biopreservatives and may help in improving the gut environment by combating several pathogenic microorganisms.