Enhanced production of poly-γ-glutamic acid by a newly-isolated Bacillus subtilis
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Application of poly-gamma-glutamic acid (γ-PGA), an unusual macromolecular anionic polypeptide, is limited due to the high cost associated with its low productivity. Screening bacterial strains to find a more efficient producer is one approach to overcome this limitation. Strain MJ80 was isolated as a γ-PGA producer among 1,500 bacterial colonies obtained from soil samples. It was identified as Bacillus subtilis, based on the biochemical and morphological properties and 16S rDNA gene sequencing. It produced γ-PGA from both glutamic acid and soybean powder, identifying it as a facultative glutamic acid-metabolizing bacterium. After optimization of its culture conditions, B. subtilis MJ80 showed γ-PGA productivity of 75.5 and 68.7 g/l in 3 and 300 l jar fermenters for 3 days cultivation, respectively, the highest productivity reported to date, suggesting MJ80 to be a promising strain for γ-PGA production.
KeywordsAnionic polypeptide Bacillus subtilis MJ80 Glutamic acid γ-PGA Poly-γ-glutamic acid
This work was supported by a grant from the Next-Generation BioGreen 21 Program (No.PJ007983), Rural Development Administration (RDA), Republic of Korea.