University of Illinois Urbana-Champaign

Understanding the intrinsic antibiotic resistance in Lysobacter enzymogenes, a ubiquitous environmental bacterium

Yu, Menghao

Content Files
YU-DISSERTATION-2020.pdf

Permalink

https://hdl.handle.net/2142/108670

Description

Title
Understanding the intrinsic antibiotic resistance in Lysobacter enzymogenes, a ubiquitous environmental bacterium
Author(s)
Yu, Menghao
Issue Date
2020-07-10
Director of Research (if dissertation) or Advisor (if thesis)
Zhao, Youfu
Doctoral Committee Chair(s)
Zhao, Youfu
Committee Member(s)
  • Schroeder, Nathan
  • Mideros, Santiago
  • Hind, Sarah Refi
Department of Study
Crop Sciences
Discipline
Crop Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2020-10-07T22:48:10Z
Keyword(s)
  • Lysobacter
  • Intrinsic resistance
  • Ampicillin
  • Spectinomycin
  • CsrA
Abstract
Antibiotics are one of the most important tools in modern medicine. Unfortunately, due to frequent use of antibiotics in clinical and agricultural areas, more bacterial strains in diverse environmental settings have been found to be resistant to many antibiotics, resulting in multidrug resistance (MDR). Increased understanding of antibiotic resistance in environmental bacteria provides new targets for discovery of novel therapeutics. However, little is known about the antibiotic resistance of the vast majority of environmental bacteria. The ubiquitous Gram-negative Lysobacter bacteria, as promising biocontrol agents, confer intrinsic antibiotic resistance and could be used as a model in understanding antibiotic resistance in non-clinical environments. First, to fill a critical knowledge gap in the prevalence and diversity of MDR in Lysobacter, we compared two strains of Lysobacter species, i.e., LeC3 and LaATCC29479, and determined their resistance to 12 common antibiotics. Our results revealed that both strains exhibited high level of MDR, and in comparison to LaATCC29479, LeC3 exhibited even higher levels of resistance against most antibiotics tested compared to LaATCC29479. Comparative resistomic analyses identified the core resistome of Lysobacter and also revealed potential genes related to the antibiotic resistance profiles in LeC3 and LaATCC29479. Second, screening two Tn5 transposon mutant libraries of LeC3 recovered 12 and 19 mutants with decreased ampicillin and spectinomycin resistance, respectively. Further characterization of selected mutants showed that cell permeability, β-lactamase activity and transport contributed to high level of resistance to ampicillin in LeC3; whereas high level of resistance to spectinomycin in LeC3 was mostly due to its ribosomal RNA target as well as related to cell-wall recycling and purine biosynthesis. Third, we demonstrated that the post-transcriptional regulator CsrA not only conferred MDR, but also contributed to biocontrol activity in LeC3. Furthermore, two putative small regulatory RNAs (sRNAs), referred to as csrB and csrC, were identified in the genome of LeC3. Double mutation of csrB and csrC in LeC3 led to increased resistance to nalidixic acid, rifampicin, and kanamycin. Collectively, this project paves the way for further MDR studies using Lysobacter bacteria.
Graduation Semester
2020-08
Type of Resource
Thesis
Permalink
http://hdl.handle.net/2142/108670
Copyright and License Information
Copyright 2020 Menghao Yu

Owning Collections

Graduate Dissertations and Theses at Illinois PRIMARY
Graduate Theses and Dissertations at Illinois
Dissertations and Theses - Crop Sciences