九州工業大学　情報工学部

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