Effects of cpxR on the growth characteristics and antibiotic production of Xenorhabdus nematophila. Issue 3 (8th January 2019)

• Record Type: Journal Article
• Authors: Guo, Shuqi; Wang, Zeyu; Liu, Beiling; Gao, Jiangtao; Fang, Xiangling; Tang, Qian; Bilal, Muhammad; Wang, Yonghong; Zhang, Xing
• Is Part Of: Microbial biotechnology. Volume 12:Issue 3(2019:May)
• Page Start: 447
• Page End: 458
• Publication Date: 2019-01-08
• Subjects: Microbial biotechnology -- Periodicals; Biotechnology; Microbiology; 660.62
• DOI: 10.1111/1751-7915.13362
• Languages: English
• ISSNs: 1751-7915

Abstract

Summary: CpxR is a global response regulator that negatively influences the antimicrobial activities of Xenorhabdus nematophila . Herein, the wildtype and Δ cpxR mutant of X. nematophila were cultured in a 5‐l and 70‐l bioreactor. The kinetic analysis showed that Δ cpxR significantly increased the cell biomass and antibiotic activity. The maximum dry cell weight (DCW) and antibiotic activity of Δ cpxR 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. Xenocoumacin 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 Δ cpxR, where Δ cpxR was sensitive to alkaline pH conditions. The optimal cell growth and antibiotic activity of Δ cpxR 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 Δ cpxR considerably increased the biomass of X. nematophila at a late stage of fermentation. In addition, Δ cpxR significantly promoted the biosynthesis of Xcns but decreased the production of nematophin. Abstract : ·Deleting cpxR of X. nematophila results in a prolonged lag phase, and lower biomass at early‐ and mid‐stage of fermentation, but significantly increased the biomass at a late stage in contrast to the wildtype. Deleting cpxR of X. nematophila promoted the production of Xcns, but decreased the production of nematophin. Δ cpxR mutant was hypersensitive to alkaline condition and exhibited lower biomass under pH 8.5.