Studies of a γ-Polyglutamic Acid-Producing Bacillus Strain Isolated from Chinese Fermented Soybean Foods

摘要

In this study, we isolated a bacterium Dg5041 which can synthesis γ-polyglutamic acid (γ-PGA) from the Chinese natto-like fermented soybean food. This γ-PGA-producing strain was studied by phenotypic, phylogenetic, spectrophotometric and HPLC analyses. Based on 16S rRNA gene sequences, a phylogenetic tree was constructed and showed that isolate Dg5041 and Bacillus subtilis were in the same cluster. According to the phenotypic and phylogenetic outcomes of this report, the strain Dg5041 can be identified as B. subtilis. The supernatant of the fermentation broth after centrifugation was determined by CTAB method, and the yield of γ-PGA reached 18.04 g L -1 , reaching the higher level than reported in the literature. The γ-PGA fermentation product has a maximum absorption peak at 192 nm, indicating that the purified product is almost a single product, consistent with γ-PGA standard products. The HPLC chromatogram of hydrolyzed γ-PGA spectrum studies verified that the hydrolysate of γ-PGA fermentation product was glutamate.