Optimization of process parameters for key enzymes accumulation of 1,3-propanediol production from Klebsiella pneumoniae

Under microaerobic condition, key enzymes (glycerol dehydrogenase GDH, 1,3-propanediol oxidoreductase PDOR, glycerol dehydratase GDHt) accumulation of 1,3-propanediol production by Klebsiella pneumoniae was studied. Several carbon sources, organic nutrients, inorganic nitrogen sources and salts were examined for their effects on key enzymes formation. Uniform design and genetic algorithms (GAs) coupling artificial neural networks (ANNs) were developed for the medium optimization. Meanwhile, the optimization of fermentation conditions (initial pH, rotor speed, temperature and inoculum) was conducted. When the strain grew in the optimized medium under optimal fermentation condition in a 5 L stirred tank bioreactor for batch production, GDH, PDOR and GDHt activities were 3700, 3840 and 8.70 U referred to 1 L of fermentation broth after 20 h cultivation and the productivities of GDH, PDOR and GDHt (U/L h) were 185, 192, 0.435 and the maximun concentration of 1,3-PD was 10.5 g/L. Result show that productions of GDH, PDOR and GDHt with K. pneumoniae can be carried out under microaerobic condition and the increment of key enzyme activities is essential to 1,3-PD formation.