Effect of by-products on cell growth and biosynthesis of 1,3-propanediol by klebsiella pneumoniae

Biosynthesis of 1,3-propanediol attracted much attention recently. The cell growth and biosynthesis of 1,3-propanediol by Klebsiella pneumoniae tended to be ceased in the latter phase of anaerobic culture. The effect of environmental factors was studied in this work. It was indicated that the main by-product ethanol was the key inhibitor. Addition of 4 g / L ethanol in the culture medium would restrain the cell growth and 1,3-propanediol formation. By addition of 8 g / L ethanol, the maximum specific rates of cell growth and 1,3-propanediol biosynthesis, the maximum concentrations of biomass and 1,3-propanediol were decreased by 21.6%, 22.1%, 59.6% and 33.5% respectively. The inhibition potentials of other by-products on the anaerobic growth of K. pneumoniae were also detected. It was shown that the cell growth was inhibited obviously with 2 g / L acetic acid, yet it would not be affected even with 5 g / L 2,3-butanediol or 10 g / L lactic acid.