Candida glycerinogenes不同碳源代谢的初步研究

Candida glycerinogenes metabolic fermentation using different carbon sources

研究了不同碳源对Candida glycerinogenes的菌体生长、发酵液pH值及代谢产物的影响,结果发现以葡萄糖、果糖等单糖为碳源时菌体生长较快,最终生物量比以蔗糖、麦芽糖等二糖为碳源时高20%～30%;导致发酵前12 h发酵液pH值明显下降的主要因素是乳酸;与葡萄糖为碳源转化为甘油相比,果糖为碳源时更易累积乙醇;以蔗糖、麦芽糖为碳源时,用于转化生成甘油的碳源明显降低,碳源主要用于菌体自身生物合成及HMP途径,以蔗糖为碳源时,用于乳酸、丙酸及柠檬酸生物合成的碳源较麦芽糖明显提高,TCA途径代谢较为活跃。

The effects of different carbon sources such as glucose, fructose, sucrose and maltose used as the substrates on fermentation, analysis of biomass, pH and metabolites by Cand/da glycerinogenes were investigated. The results indicated that the biomass grew quickly when monosaccharide such as glucose, fructose was used as the carbon source, and the final biomass was 20 % -30 % higher than that of sucrose or maltose used. In all fermentation using different carbon sources, the pH declined significantly within the first 12 h, and then the pH rose slowly. It was found that the main factor influencing pH was lactic acid. Using different carbon sources as the substrates in fermentation, there were different effects on metabolism. At 60 h of fermentation, using glucose as the carbon source, the conversion rate of glycerol was 45.63 % and it was the highest; using fructose, the conversion rate of glycerol was 40.37 %. On the other hand, more ethanol was produced by using fructose than using glucose. With sucrose, maltose as the carbon sources, the yield of glycerol was significantly lower, and most of the carbon source was mainly used for the biosynthesis and HMP. In sucrose, the biosynthesis of lactic acid, propionic acid and citric acid were improved obviously compared with maltose, and TCA metabolism was more exuberant.