Effects of cpxR on the growth characteristics and antibiotic production of Xenorhabdus nematophila

       論文信息：Shuqi Guo, Zeyu Wang, Beiling Liu, Jiangtao Gao, Xiangling Fang, Qian Tang,Muhammad Bilal, Yonghong Wang*and Xing Zhang.Effects of cpxR on the growth characteristics and antibiotic production of Xenorhabdus nematophila. Microbial Biotechnology.

       JCR分區(qū)Q1，中科院大類分區(qū)二區(qū)，IF=3.913

       論文摘要： CpxR is a global response regulator that negatively influences the antimicrobial activities of Xenorhabdus nematophila. Herein, the wildtype and DcpxR mutant of X. nematophila were cultured in a 5-l and 70-l biore-actor. The kinetic analysis showed that DcpxR signifi-cantly increased the cell biomass and antibiotic activity. The maximum dry cell weight (DCW) and  antibiotic activity of DcpxR were 20.77 ? 1.56 g L ?1 and 492.0 ? 31.2 U ml ?1 and increased by 17.28 and 97.33% compared to the wildtype respectively. Xeno-coumacin 1 (Xcn1), a major antimicrobial compound,was increased 3.07-fold, but nematophin was decreased by 48.7%. In 70-l bioreactor, DCW was increased by 18.97%, while antibiotic activity and Xcn1 were decreased by 27.71% and 11.0% compared to that in 5-l bioreactor respectively. Notably, pH had remarkable effects on the cell biomass and antibiotic activity of DcpxR, where DcpxR was sensitive to alka-line pH conditions. The optimal cell growth and antibi-otic activity of DcpxR occurred at pH 7.0, while Xcn1 was increased 5.45- and 3.87-fold relative to that at pH 5.5 and 8.5 respectively. These findings confirmed that DcpxR considerably increased the biomass of X.nematophila at a late stage of fermentation. In addi-tion, DcpxR significantly promoted the biosynthesis of  Xcns but decreased the production of nematophin.