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Bioprospecting of Extremophilic Microorganisms to Address Environmental Pollution
Published on: December 30, 2021
Using auxotrophic donor strains to explore pQBR57 plasmid host range among environmental soil bacterial isolates
Alejandro Marquiegui-Alvaro1,2, Anastasia Kottara2, Matthew J N Thomas2
1Manchester Institute of Biotechnology (MIB), Department of Chemistry, University of Manchester, Manchester, M1 7DN, UK.
Microbiology (Reading, England)
|July 10, 2026
Summary
This study explored plasmid host range (PHR) in soil bacteria using a new screening method. Donor strain identity significantly impacted gene transfer, revealing defence systems that block plasmid acquisition in some bacteria.
Area of Science:
- Environmental microbiology
- Molecular biology
- Biotechnology
Background:
- Plasmid host range (PHR) is crucial for gene dissemination and biotechnology applications.
- Previous PHR studies often overlook donor strain influence and require engineered recipients.
- A high-throughput method is needed to study PHR in diverse environmental bacteria.
Purpose of the Study:
- To develop and apply an auxotrophic donor counter-selection method for scalable PHR screening.
- To investigate the impact of donor strain identity on plasmid conjugation efficiency.
- To identify genetic barriers limiting plasmid acquisition in environmental isolates.
Main Methods:
- Utilized two auxotrophic donor strains (Pseudomonas fluorescens and Pseudomonas putida) and a bioremediation plasmid (pQBR57-tphKAB).
- Screened 101 diverse soil bacterial isolates as potential recipients.
- Employed phylogenomic analysis to characterize transconjugant lineages and identify defence systems.
Main Results:
- Conjugation was observed only within the Pseudomonas genus.
- Pseudomonas fluorescens demonstrated broader PHR, successfully conjugating the plasmid into more strains than Pseudomonas putida.
- Transconjugants belonged to the Pseudomonas citronellolis lineage; related non-conjugating strains possessed defence systems hindering plasmid uptake.
Conclusions:
- Auxotrophic donor counter-selection is an effective, scalable method for PHR assessment in environmental bacteria.
- Donor strain characteristics significantly influence plasmid conjugation success.
- Identified defence systems represent barriers to horizontal gene transfer and can be targets for microbiome engineering.
