Isolation and genomic characterization of Klebsiella Lw3 with polychlorinated biphenyl degradability

ABSTRACT

Bioremediation of sediment organic pollution has been intensely investigated, but the degradation of complex organic compounds, pesticide residues, and polychlorinated biphenyls (PCBs) remains poorly studied. In this study, sediments were collected from Zhanjiang Mangrove Reserve and inoculated in an inorganic salt medium using only biphenyl (BP) and PCBs as the carbon sources to obtain a PCB-degrading strain. A gram-negative bacterium that metabolized PCBs was isolated and identified as Klebsiella Lw3 by 16S rDNA phylogenetic analysis. Genomic sequencing showed that this bacterium possessed genes related to BP/PCB degradation, and its GC content was 58.2%; we identified 3326 cellular pathways. Gas chromatography–mass spectrometry was employed to test the PCB degrading ability; the results showed that the strain had a good degradation effect on PCB3 at concentrations of 5, 10, 20, 40, and 60 mg/L and that the final degradation rate was higher than 97% after 96 h. Interestingly, this strain showed good biodegradability of PCBs despite having no classical PCB degradation pathway, providing a new direction for Klebsiella research with practical significance for in situ bioremediation of PCB contamination. Overall, this study provides valuable insights into the genetic structure of PCB-degrading strains as well as eco-friendly and low-cost PCB degradation and lays a foundation for the discovery of new degradation pathways.

GRAPHICAL ABSTRACT

KEYWORDS:

• 16S rRNA
• Degradability
• Genomic sequencing
• Klebsiella
• Mangrove
• Polychlorinated biphenyl

Acknowledgments

The authors are grateful to the staff of the College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, China, for providing technical assistance and support during the course of the study. This research was supported by the Marine Economic Development Project of Guangdong Province Special Fund for Promoting High-quality Economic Development (Contract grant number: GDOE2019A52), Guangdong Postgraduate Education Innovation Project (2020SFJD001), and International Science and Technology Cooperation Project of Guangdong Province (Contract grant number: 2016A050502062).

Geolocation information

China

Declaration of interest statement

The authors report there are no competing interests to declare.

Ethics approval and consent to participate

Not applicable

Consent for publication

Not applicable

Data availability statement

The data that support the findings of this study are available on request from the corresponding author [Chen. J.-J].

Disclosure statement

No potential conflict of interest was reported by the authors .

Additional information

Funding

This work was supported by: Marine Economic Development Project of Guangdong Province Special Fund for Promoting High-quality Economic Development [grant number GDOE2019A52]: R & D on Degradation of DL-PCBs and Microplastics Exposure to Microbes in South China Sea (Zhanjiang) and Guangdong Provincial International Sci-Tech Collaborative Project [grant number 2016A050502062]: Application Research on Detection of DL-PCBs Pollution in Seashore Sediments by GC-ECD & Zebrafish Embryonic Toxicology.