Evaluation of γ-Aminobutyric Acid Production by Indigenously Isolated Lactic Acid Bacteria

Abstract

GABA is a major inhibitory neurotransmitter in mammalian brain and has several well-known physiological functions. Lactic acid bacteria possess special physiological activities and regarded as safe. Therefore, various types of LAB that show GABA-producing ability is an interesting target for food industry, especially fermented foods because individual strain has specific fermentation profiles such as acid production, taste and flavor formation ability. These profiles are considered as important factors in the use of LAB as starter cultures in the production of fermented foods. In the present report, two preisolated lactic acid bacteria were screened to be high GABA producing strains namely, Lactococcus lactis and Leuconostoc mesenteroides. The culture media used for effective GABA production was MRS supplemented with 5% MSG, when inoculated with the cultures and kept at 30°C for 48h with an initial pH 5 on static condition. The optimized conditions were used to prepare a fermented food product having high nutritional value. The raw material used in the food product was wheat flour in place of media and MSG was replaced by Vigna mungo (17-34% glutamate). The GABA concentration obtained with MRS supplemented with 5 % MSG was140mM (14.4g/l) and 80mM (8.2g/l) with L. lactis and L. mesenteroides resp. and in the food product prepared with Vigna mungo and wheat flour was 110mM (11.3g/l) with mixed culture (L. lactis and L. mesenteroides). In comparison to media, our final food product produces significant amount of GABA which can be easily consumed and absorbed in the body. Keywords: Lactococcus lactis, Leuconostoc mesenteroides, bhaturu, GABA (Gamma-aminobutyric acid), vigna mungo, monosodium glutamate.