トップページ » 主催講演会のお知らせ » 「Kinetic, dynamic and metabolic analysis of continuous bioconversion of glycerol into 1,3-propanediol by Klebsiella pneumoniae」 7月28日開催
日 時:平成 22年 7月 28日(水)AM:11:15-12:30 場 所:2F 大学院セミナー室 講演者:Xiu Zhilong教授(大連理工大学)
概要: 微生物プロセスのモデリングや、最近注目されている、1,3-プロパンジオール の発酵生産に関する最近の研究成果について発表し、意見交換を行う。 The bioconversion of glycerol to 1,3-propanediol (1,3-PD) was particularly attractive to industry because of renewable feedstock and potential uses of 1,3-PD. Based on the metabolite overflow kinetics for substrate consumption and product formation, optimization of glycerol biodissimilation to 1,3-propanediol by K. pneumoniae was conducted in one- and two-stage continuous anaerobic cultures. Nonlinear enzyme-catalytic and gene-regulated kinetics were postulated to describe the continuous fermentations of glycerol by K. pneumoniae. Analysis of multiplicity and hysteresis was investigated. The intermediate, 3-hydroxypropionaldehyde, plays an important role in expression of dha regulon and activities of key enzymes in glycerol metabolism. Metabolic flux analysis of glycerol fermentation revealed that the branch points of glycerol and dihydroxyacetonephosphate were rigid to the environmental conditions. However, the pyruvate and acetyl coenzyme A metabolisms gave cells the flexibility to regulate the energy and intermediate fluxes under various environmental conditions. The theoretical optimal 1,3-PD yield could reach to 0.844 mol mol-1 if the pentose phosphate pathway (PPP), and transhydrogenase had a high flux under anaerobic condition. Relaxation of the coenzyme specificity of 1,3-propanediol oxidoreductase for both NADH and NADPH would increase the production of 1,3-propanediol. Computational alaninescanning mutagenesis of the active site residues illustrated that Asp41 was the key residue responsible for the coenzyme specificity. Site-directed mutagenesis was conducted and the relaxation was successfully realized.世話人:清水和幸