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Bioresour Technol. 2011 Mar;102(5):4251-7. doi: 10.1016/j.biortech.2010.12.065. Epub 2010 Dec 22.

Glutamic acid independent production of poly-γ-glutamic acid by Bacillus amyloliquefaciens LL3 and cloning of pgsBCA genes.

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Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, Tianjin 300071, PR China.


A new glutamic acid independent poly-γ-glutamic acid (γ-PGA) producing strain, which was identified as Bacillus amyloliquefaciens LL3 by analysis of 16S rDNA and gyrase subunit A gene (gyrA), was isolated from fermented food. The product had a molecular weight of 470, 801 and l-glutamate monomer content of 98.47%. The pre-optimal medium, based on single-factor tests and orthogonal design, contained 50 g/L sucrose, 2g/L (NH(4))(2)SO(4), 0.6g/L MgSO(4), and provided well-balanced changes in processing parameters and a γ-PGA yield of 4.36 g/L in 200 L system. The γ-PGA synthetase genes pgsBCA were cloned from LL3, and successfully expressed by pTrcLpgs vector in Escherichia coli JM109, resulting the synthesis of γ-PGA without glutamate. This study demonstrates the designedly improved yield of γ-PGA in 200 L system and the first report of pgsBCA from glutamic acid independent strain, which will benefit the metabolized mechanism investigation and the wide-ranging application of γ-PGA.

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