中国生物工程杂志

Bio-production of 1, 3-propanediol (1,3-PD) has attracted much attention recently, and it exhibits a wide range of potential utilizations, especially as monomer for the synthesis of polypropylene terephtalate (PPT). Bio-conversion from glycerol to 1,3-PD by bacterial species Klebsiella pneumoniae was investigated by fed-batch fermentation and regulated by nutrient substances limited culture. Depending on product formation directly linked to cell growth, evidence was provided that nitrogen could constitute a limiting factor for manipulating cell growth by controlling NH4Cl concentration, it is found that an adequate nitrogen level for glycerol fermentation into 1,3-PD was efficient in converting glycerol into 1,3-PD. Under less nitrogen concentration, biomass yield decreased resulting a less 1,3-PD yield. Under excess nitrogen concentration, an increase of biomass yield and specific growth rate did not help production, this was attributed to much more consumption of glycerol on cell growth and metabolize. It was clearly shown that the volumetric productivity and molar convertion yield reached a high level by controlling nitrogen supply with the NH4Cl fed rate of 0.41 g/(L•h) and the residual concentration below 0.1 g/L. After 25-28 hours, the final concentration, the volumetric productivity, molar convention yield of 1,3-PD in fed-batch fermentation under nutrient limited conditions were 52.03 g/L, 2.04 g/(L•h), 0.66 respectively, increased 28.0 %, 35.1 % and 29.4 % over control. In this way an efficient microbial production 1,3-PD from glycerol was demonstrated by controlling the specific growth rate of cell through limited NH4Cl regulation, and then both the productivity and molar yield would increase effectively.