Isolation of Bacillus subtilis GS-2 producing gamma-PGA from Ghungkukjang bean paste and identification of gamma-PGA = 청국장으로부터 분리한 Poly(gamma-glutamic acid)를 생산하는 균주 Bacillus subtilis GS-2의 분리 및 gamma-PGA의 확인

Abstract

γ-PGA(poly-γ-glutamic acid) is an unusual anionic polypeptide that is made of D- and L-glutamic acid units connected by amide linkages between α-amino and γ-carboxylic acid groups. γ-PGA has been isolated from many kinds of organisms. Many Bacillus strains produce γ-PGA as a capsular material of an extracellular viscous material. It is safe for eating as a viscosity element of fermented soybean products such as Chungkookjang and Natto. It is biodegradable, edible and nontoxic toward humans and the environment and its molecular weight varies from ten thousand to several hundred thousand depending on the kinds of strains used. Therefore, potential applications of γ-PGA and its derivatives have been of interest in the past few years in a broad range of industrial fields such as food, cosmetics, medicine, water-treatment, etc. In this study, a bacterium, Bacillus subtilis GS-2 isolated from the Korean traditional seasoning food, Chungkookjang could produce a large amount of γ-PGA with high productivity and had a simple nutrient requirement. Based on carbon utilization pattern and partial 16S rRNA sequence analysis, the GS-2 strain was identified as B. subtilis. The determination of purified γ-PGA was confirmed with thin layer chromatography (TLC), high performance liquid chromatography (HPLC), fourier transform infrared (FT-IR) spectra, and 1H-nuclear magnetic resonance (1H-NMR) spectroscopy.