title: Impact of acquisition of 16S rRNA methylase RmtB on the fitness of Escherichia coli.
abstract: The aim of this study was to elucidate the biological phenotypes of 16S rRNA methylase RmtB in Escherichia coli and the impact of RmtB acquisition on the fitness of the target bacterium. An rmtB in-frame deletion mutant in E. coli was constructed using a suicide vector (pDMS197)-based double crossover allelic exchange, and its corresponding complemented strain was established. Combined studies of microdilution susceptibility testing, conjugation experiments, growth kinetics assays, competitive experiments, biofilm formation tests and motility assays were performed to study the rmtB-mediated fitness among the prototype E. coli strain, its isogenic mutant and the corresponding complemented strain. The minimum inhibitory concentrations (MICs) of 4,6-disubstituted 2-deoxystreptamines for the rmtB wild-type strain, its isogenic mutant and the complemented strain were ≥1024, ≤2 and ≥1024mg/L, respectively. Both the growth rates and the competitive abilities of the wild-type and complemented strains were relatively inferior to the ΔrmtB mutant. There was no significant difference in biofilm formation and motility among the three strains. In conclusion, the data presented here suggest that acquisition of the 16S rRNA methylase gene rmtB in E. coli can exact a fitness cost on the bacteria, subsequently reducing the growth rate slightly and decreasing the competitive capacity of the bacterium, whereas it does not affect biofilm formation or motility.
authors.affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
authors.forename: Bingming
authors.initials: B
authors.lastname: Ou
authors.affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China; Jiangsu Agri-animal Husbandry Vocational College, Taizhou 225300, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
authors.forename: Yujie
authors.initials: Y
authors.lastname: Song
authors.affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China; Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Luan
authors.initials: L
authors.lastname: Li
authors.affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Wai Liang
authors.initials: WL
authors.lastname: Tham
authors.affiliation: Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD 57007, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Francis
authors.affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China. Electronic address: yzgqzhu@yzu.edu.cn.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Zhu
mesh_terms: D000900:Anti-Bacterial Agents; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D029968:Escherichia coli Proteins / Q000235:genetics*; D056084:Genetic Fitness; D008780:Methyltransferases / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D017384:Sequence Deletion
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D008780:Methyltransferases; C540682:RmtB protein, E coli
keywords: 16S rRNA methylase RmtB; Aminoglycosides; Biofilm formation; Competitive ability; Deletion mutation; Growth rate