Efficient production of poly-γ-glutamic acid by bacillus subtilis ZJU-7

Authors: Shi, Feng¹; Xu, Zhinan²; Cen, Peilin¹

Source: Applied Biochemistry and Biotechnology, Volume 133, Number 3, June 2006 , pp. 271-281(11)

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Abstract:

A strain with high poly-γ-glutamic acid (γ-PGA) production was isolated from fermented bean curd, a traditional Chinese food. The strain was named bacillus subtilis ZJU-7 according to 16s rDNA sequencing and its taxonomic characters. The culture conditions for γ-PGA production were evaluated. The most suitable carbon and nitrogen sources were sucrose and tryptone, respectively. Exogenous l-glutamic acid was necessary for γ-PGA production, and the production of γ-PGA increased on the addition of l-glutamic acid to the medium. In the medium containing 60 g/L of sucrose, 60 g/L of tryptone, 80 g/L of l-glutamic acid, and 10 g/L of NaCl, the yield of γ-PGA reached 54.4 g/L after cultivation at 37°C for 24h, which was the highest γ-PGA production compared with values reported in the literature. The average molecular mass of γ-PGA produced was about 1.24×10⁶ Daltons. B. subtilis ZJU-7 is genetically stable and can synthesize levan instead of γ-PGA without the addition of l-glutamic acid to the medium.

Keywords: Poly-γ-glutamic acid; 16s rDNA; l-glutamic acid; sucrose; bacillus subtilis

Document Type: Research article

DOI: http://dx.doi.org/10.1385/ABAB:133:3:271

Affiliations: 1: Institute of Bioengineering, Department of Chemical Engineering and Bioengineering, Zhejiang University, 310027, Hangzhou, China, 2: Institute of Bioengineering, Department of Chemical Engineering and Bioengineering, Zhejiang University, 310027, Hangzhou, China, Email: znxu@zju.edu.cn

Publication date: 2006-06-01