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Studies On Culture Conditions And Kinetics For Poly γ-Glutamate Production With Bacillus Subtilis

Posted on:2007-04-09Degree:MasterType:Thesis
Country:ChinaCandidate:G Y NieFull Text:PDF
GTID:2121360182488749Subject:Biochemical Engineering
Abstract/Summary:PDF Full Text Request
Poly-γ-glutamic acid (γ-PGA) is a kind of water-soluble and biodegradable anionic polypeptide that is made of D- and L-glutamic acid units linked by amide linkages between a-amino and γ-carboxylic acid groups. It has various applications in industrial fields, such as medicine, food and agriculture, cosmetics and water treatment, etc.A bioprocess for the y-PGA production was developed by strain screening, culture condition optimization in shake flasks and further scaled up fermentation in in 5L jar fermentor scale. The effects of different fermenatation conditions, such as stirring rate, aeration rate, temperature was investigated with regard to PGA production in the bench-top fermentor. The final optimal conditions were determined as followed: cultivation at 37 °C in medium containing 80g/L L-glutamine, 60 g/L sucrose, 60 g/L tryptone, 15 g/L NaCl, pH7;strring rate 200r/min;aeration rate 1.0vvm. The highest productivity of γ-PGA (50.2g/L) could be abtained under the above optimal conditions..On the basis of Logistic and Luedeking-Piret equation and the experimental data of batch fermentation in the 5L fermentation reactor, the mathematical models were proposed to describe the fermentation process with Bacillus subtilis ZJU-7. The parameters of the models were established by using MATLAB software with experimental data and the models.The modes consist of:Cell growth model Production formation model Substrate depletion modelThe above models could fit the profiles of cell growth, production formation and substrate depletion well. It might be helpful to understand and guide further optimization of PGA fermentation in the future.
Keywords/Search Tags:poly γ-glutamic acid, Bacillus subtilis, cultivation condition optimization, the Producing Kinetics model, fit
PDF Full Text Request
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