Article

Biotechnology and Bioprocess Engineering

, Volume 11, Issue 3, pp 251-257

First online:

Optimization of γ-polyglutamic acid production byBacillus subtilis ZJU-7 using a surface-response methodology

  • Feng ShiAffiliated withInstitute of Bioengineering, Department of Chemical Engineering and Bioengineering, Zhejiang University
  • , Zhinan XuAffiliated withInstitute of Bioengineering, Department of Chemical Engineering and Bioengineering, Zhejiang University Email author 
  • , Peilin CenAffiliated withInstitute of Bioengineering, Department of Chemical Engineering and Bioengineering, Zhejiang University

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Abstract

The components of the media used to elicit the biosynthesis of poly-γ-glutamic acid (γ-PGA) byBacillus subtilis ZJU-7 were investigated, particularly the carbon and nitrogen sources. Of the 7 carbon sources investigated, sucrose induced the highest rate of γ-PGA productivity; among the nitrogen sources, tryptone had the best effect for γ-PGA production. A 26−2 fractional factorial design was used to screen factors that influence γ-PGA production significantly, and a central composite design was finally adopted to formulate the optimal medium. γ-PGA productivity improved approximately 2-fold when the optimal medium was used compared with the original nonoptimized medium, and volumetric productivity reached a maximum of 58.2 g/L after a 24-h cultivation period.

Keywords

poly-γ-glutamic acid l-glutamic acid Bacillus subtilis response surface methodology