Duan Xiangke, Pan Yanrong, Cai Zhao, Liu Yumei, Zhang Yingdan, Liu Moxiao, Liu Yang, Wang Ke, Zhang Lianhui, Yang Liang
Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, 510642, Guangdong, People's Republic of China.
School of Medicine, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, People's Republic of China.
Cell Biosci. 2021 Jul 21;11(1):138. doi: 10.1186/s13578-021-00655-9.
Pseudomonas aeruginosa is a notorious opportunistic pathogen causing various types of biofilm-related infections. Biofilm formation is a unique microbial strategy that allows P. aeruginosa to survive adverse conditions such as antibiotic treatment and human immune clearance.
In this study, we experimentally evolved P. aeruginosa PAO1 biofilms for cyclic treatment in the presence of high dose of imipenem, and enriched hyperbiofilm mutants within six cycles in two independent lineages. The competition assay showed that the evolved hyperbiofilm mutants can outcompete the ancestral strain within biofilms but not in planktonic cultures. Whole-genome sequencing analysis revealed the hyperbiofilm phenotype is caused by point mutations in rpoS gene in all independently evolved mutants and the same mutation was found in P. aeruginosa clinical isolates. We further showed that mutation in rpoS gene increased the intracellular c-di-GMP level by turning on the expression of the diguanylate cyclases. Mutation in rpoS increased pyocyanin production and virulence in hyperbiofilm variants.
Here, our study revealed that antibiotic treatment of biofilm-related P. aeruginosa infections might induce a hyperbiofilm phenotype via rpoS mutation, which might partially explain antimicrobial treatment failure of many P. aeruginosa biofilm-related infections.
铜绿假单胞菌是一种臭名昭著的机会致病菌，可引起各种与生物膜相关的感染。生物膜形成是一种独特的微生物策略，使铜绿假单胞菌能够在诸如抗生素治疗和人体免疫清除等不利条件下存活。
在本研究中，我们在高剂量亚胺培南存在的情况下对铜绿假单胞菌PAO1生物膜进行循环处理，通过实验使其进化，并在两个独立谱系的六个循环内富集了超生物膜突变体。竞争试验表明，进化后的超生物膜突变体在生物膜内能够胜过原始菌株，但在浮游培养物中则不然。全基因组测序分析表明，所有独立进化的突变体中，超生物膜表型是由rpoS基因的点突变引起的，并且在铜绿假单胞菌临床分离株中也发现了相同的突变。我们进一步表明，rpoS基因的突变通过开启双鸟苷酸环化酶的表达增加了细胞内c-di-GMP水平。rpoS突变增加了超生物膜变体中绿脓菌素的产生和毒力。
在此，我们的研究表明，抗生素治疗与生物膜相关的铜绿假单胞菌感染可能通过rpoS突变诱导超生物膜表型，这可能部分解释了许多与铜绿假单胞菌生物膜相关感染的抗菌治疗失败。
