Production of Ultra-high Molecular Weight Poly-γ-Glutamic Acid with Bacillus licheniformis P-104 and Characterization of its Flocculation Properties

A novel strain of Bacillus licheniformis P-104 was isolated from Chinese soybean paste to produce a bioflocculant. The bioflocculant was confirmed as ultra-high molecular weight poly-γ-glutamic acid (γ-PGA) using Fourier transform infrared spectrum, high-performance liquid chromatography, and gel pe...

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Bibliographic Details
Published in:Applied biochemistry and biotechnology 2013-06, Vol.170 (3), p.562-572
Main Authors: Zhao, Caifeng, Zhang, Yewei, Wei, Xuetuan, Hu, Zhongbo, Zhu, Feiyan, Xu, Lin, Luo, Mingfang, Liu, Huizhou
Format: Article
Language:English
Subjects:
Bacillus - drug effects
Bacillus - genetics
Bacillus - metabolism
Bacillus licheniformis
Biochemistry
Biological and medical sciences
Biotechnology
Calcium Chloride - pharmacology
Chemistry
Chemistry and Materials Science
Fermentation
Flocculation - drug effects
Fundamental and applied biological sciences. Psychology
Glycine max - microbiology
Hydrogen-Ion Concentration
Methods. Procedures. Technologies
Microbial engineering. Fermentation and microbial culture technology
Molecular Weight
Phylogeny
Polyglutamic Acid - analogs & derivatives
Polyglutamic Acid - biosynthesis
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Summary:A novel strain of Bacillus licheniformis P-104 was isolated from Chinese soybean paste to produce a bioflocculant. The bioflocculant was confirmed as ultra-high molecular weight poly-γ-glutamic acid (γ-PGA) using Fourier transform infrared spectrum, high-performance liquid chromatography, and gel permeation chromatography with multi-angle laser light scattering. The production technology and flocculation properties of γ-PGA were investigated. By fed-batch fermentation in a 7-L bioreactor, the maximum γ-PGA yield reached 41.6 g L −1 with a productivity rate of 1.07 g L −1  h −1 . The flocculating activity of γ-PGA for kaolin suspension was 33.5 ± 1.6 1/OD under the optimized flocculation conditions (6 mM Ca 2+ , 1.5 mg L −1 γ-PGA, and pH 6.0). The optimized dosage of γ-PGA for flocculation was just about 30 % of that of reported γ-PGA produced by other strains. Moreover, the flocculation activity of γ-PGA produced by strain P-104 was much higher than commercial γ-PGA with the molecular weight ranging 200–500 kDa and 1,500–2,500 kDa. This study provided a promising strain and an efficient method for production of ultra-high molecular weight γ-PGA which could be used as a potential green bioflocculant.
ISSN:0273-2289
1559-0291
DOI:10.1007/s12010-013-0214-2