米根霉直接发酵玉米粉生产L-（+）-乳酸的研究

摘要

In the traditional fermentation process of L-(+)-lactic acid production, high amount of corn flour used to be autoclaved with certain amount water together to make growth medium. After cooling down , this medium formed sticky gel, which was hard for further fermentation process. In this study, corn flour was sterilized first, then suspended thoroughly in sterilized water to make the growth medium. With this medium, Rhizopus oryzae NRRL395 was used to produce lactic acid. The results showed that without adding any extra nutrition, 88.8 g/L of L-(+)-lactic acid was produced with 150 g/L of corn flour growth medium. The convert rate of corn flour reached 59.2%, and convert rate of glucose reached 72.4%. In this fermentation process , no enzymatic saccharification process was need , reducing the total cost. Therefore , this new fermentation process showed high potential for the production of L-(+)-lactic acid.%以米根霉（Rhizopus oryzae） NRRL395为生产菌，玉米粉为发酵基质，对玉米粉与水两相分开灭菌冷却后混合制成玉米粉悬浊液发酵生产L-（+）-乳酸的新工艺进行了研究。试验结果表明，新工艺在不添加任何外源营养的情况下，以150 g/L天然玉米粉为培养基可产L-（+）-乳酸88.8 g/L，L-（+）-乳酸对玉米粉的转化率达到59.2%，对葡萄糖的转化率达到72.4%。该工艺克服了玉米粉在浓度较高情况下由于蒸煮灭菌冷却后呈凝胶而不能被发酵的困难；且省去酶解糖化操作，使成本降低，具有较高的应用价值。