Screening the Decreased F1-ATPase Activity Mutant of Rhizopus Oryzae for the Purpose of Enhanceing L-Lactic Acid Productivity

• 1、School of Biotechnology and Food Engineering, Hefei University of Technology

Abstract：A neomycin-resistant mutant NA-2，with the activity of F1-ATPase decreased roughly 86.82% , was breed irradiated by synchrotron soft X-ray and based on analysis of energy metabolic pathway. Strain NA-2 was cultured in a L-lactic acid fermentation medium containing 120g/L of glucose using flask. It was found that the rate of glucose consumption and L-lactic acid production were higher by 25.17% and 32.57%, and that the qs、qp and μwere higher by 86.42%、128.13% and 60.0% in the mutant than in the parent, respectively. However, the change of EC between the mutant and the parent was not significant . The content of intracellular ATP of the mutant also decreased 18.99% than that of the parent. The activities of key enzymes in glycolytic pathway of the mutant and the parent were determined. Enzymatic analysis revealed that，compared with the parent strain Rhizopus oryzae 3.819, the activities of key enzymes, phosphofructokinase, pyruvate kinase，glyceraldyde-3-phosphate dehydrogenase of the mutant NA-2 increased 58.34%，23.53% and 11.29%，respectively. The activity of LDH increased 42.27% while the activity of ADH decreased 32.11%.

Keywords： Rhizopus oryzae F1-ATPase Glycolytic pathway L-lactic acid Neomycin-resistant