Effects of phosphorus sources on glycerol production and kinetic analysis of glycerol fermentation by Candida glycerinogenes
The effects of two different phosphorus sources, corn steep liquor(CSL)and KH_2PO_4, on the growth of Candida glycerinogenes and glycerol production in batch fermentations were investigated. The glucose consumption in glycerol production, cell growth, maintenance, and byproducts formation during different fermentation phases was also analyzed kinetically.The results showed that the influence of CSL on cell growth and glucose consumption was so prominent that even minor variation of its quality or quantity caused much difference in experimental results. It was also found that the relationship between glycerol synthesis and cell growth was very close with CSL as phosphorus source,while it was rather loose with KH_2PO_4 as phosphorus source. With the increase in phosphorus concentration,glucose consumption in cell growth and maintenance was kept basically stable during the whole fermentation process. However,glucose consumption in glycerol production gradually decreased,and the byproducts which were mainly formed during the rapid growth phase increased. Further studies indicated that the yield of glycerol on glucose reached the peak of 53.44 % and 52.76 % with 14 g·L -1 CSL and 0.57 g·L -1 KH_2PO_4, respectively.Accordingly the yield of byproducts also decreased to the minimum value of 5.84 % and 4.25 %, respectively.