Improved production of poly(γ‐glutamic acid) by Bacillus subtilis RKY3 and its recovery from viscous fermentation broth as a biodegradable polymer

BACKGROUND: Physiological parameters (culture pH, aeration rate, and agitation speed) were optimized to improve γ‐PGA production by batch culture of Bacillus subtilis RKY3. The optimum conditions for recovery of γ‐PGA from highly viscous culture broth were also investigated. RESULTS: Enhanced γ‐PGA...

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Published in:Journal of chemical technology and biotechnology (1986) 2014-05, Vol.89 (5), p.728-734
Main Authors: Jeong, Gwi‐Taek, Kim, Jin‐Nam, Ryu, Hwa‐Won, Wee, Young‐Jung
Format: Article
Language:English
Subjects:
Aeration
agitation
Bacillus subtilis
biodegradability
biodegradable polymer
biotechnology
Broths
cell free system
chemical precipitation
cold
Culture
culture media
Ethanol
Ethyl alcohol
microbial physiology
molecular weight
poly(γ-glutamic acid)
polymers
Recovery
Ultrafiltration
viscosity
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Summary:BACKGROUND: Physiological parameters (culture pH, aeration rate, and agitation speed) were optimized to improve γ‐PGA production by batch culture of Bacillus subtilis RKY3. The optimum conditions for recovery of γ‐PGA from highly viscous culture broth were also investigated. RESULTS: Enhanced γ‐PGA production (41.4 g L⁻¹, 397 cP) was observed under optimized physiological culture parameters (no pH control, 1.5 L min⁻¹ aeration, and 300 rpm agitation). The cells were completely removed by diluting the viscous culture broth 7.5‐, 5.0‐, and 2.5‐fold at pH 6.0, 4.0, and 2.0, respectively. Maximum recovery of γ‐PGA was observed when the volume ratio of cell‐free culture broth to cold ethanol was 1:5 at pH 6.0. γ‐PGA with a molecular weight 100 kDa. CONCLUSION: The physiological parameters affecting γ‐PGA production were optimized, and the isolation and recovery of γ‐PGA from viscous culture broth was also evaluated. Cells were removed completely by diluting the culture broth, and precipitation of γ‐PGA using cold ethanol was better than that of other alcohols. Ultrafiltration was found to be an efficient recovery method for concentration of culture broth containing γ‐PGA. © 2013 Society of Chemical Industry
ISSN:0268-2575
1097-4660
DOI:10.1002/jctb.4178