title: The positive effects of Mn2+on nitrogen use and surfactin production byBacillus subtilisATCC 21332.
abstract: Surfactin, one of the most effective biosurfactants, has great potential in commercial applications. Studies on effective methods to reduce surfactin's production cost are always a hotspot in the research field of biosurfactants. The aim of this study was to reveal the role of Mn2+in promoting the biosynthesis of surfactin byBacillus subtilisATCC 21332, which could arise more targeted suggestions on surfactin yield promotion. In this study,B.subtiliswas cultivated in media containing different Mn2+concentrations. The obtained results showed that the yield of surfactin gradually increased upon Mn2+addition (0.001 to 0.1 mmol/L) and achieved the maximal production of 1500 mg/L, which reached 6.2-fold of the yield obtained in media without Mn2+addition. Correspondingly, the usage ratios of ammonium nitrate were improved. When the Mn2+concentration was higher than 0.05 mmol/L, nitrate became the main nitrogen source, instead of ammonium, indicating that the nitrogen utilization pattern was also changed. An increase in nitrate reductase activity was observed and the increase upon Mn2+dosage had a positive correlate with nitrate use, and then stimulated secondary metabolic activity and surfactin synthesis. On the other hand, Mn2+enhanced the glutamate synthase activity, which increased nitrogen absorption and transformation and provided more free amino acids for surfactin synthesis.
authors.affiliation: College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment of the Ministry of Education, the Collaborative Innovation Center of Advanced Technology and Equipment for Water Pollution Control, the Collaborative Innovation Center for Regional Environmental Quality, Tongji University , Shanghai , China.
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Huang
authors.affiliation: College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment of the Ministry of Education, the Collaborative Innovation Center of Advanced Technology and Equipment for Water Pollution Control, the Collaborative Innovation Center for Regional Environmental Quality, Tongji University , Shanghai , China.
authors.forename: Jia'nan
authors.initials: J
authors.lastname: Liu
authors.affiliation: College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment of the Ministry of Education, the Collaborative Innovation Center of Advanced Technology and Equipment for Water Pollution Control, the Collaborative Innovation Center for Regional Environmental Quality, Tongji University , Shanghai , China.
authors.forename: Yihan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment of the Ministry of Education, the Collaborative Innovation Center of Advanced Technology and Equipment for Water Pollution Control, the Collaborative Innovation Center for Regional Environmental Quality, Tongji University , Shanghai , China.
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.affiliation: College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment of the Ministry of Education, the Collaborative Innovation Center of Advanced Technology and Equipment for Water Pollution Control, the Collaborative Innovation Center for Regional Environmental Quality, Tongji University , Shanghai , China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Lu
keywords: Bacillus subtilis; Mn2+; enzyme activity; nitrogen metabolism; surfactin