Conjugative Plasmid pPPUT-Tik1-1 from a Permafrost Pseudomonas putida Strain and Its Present-Day Counterparts...

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Conjugative plasmids are key drivers of bacterial evolution and adaptation.
• Pseudomonas species are ubiquitous in various environments and include important human pathogens.
• Understanding plasmid diversity and function is crucial for combating antibiotic resistance and managing microbial ecosystems.

Purpose of the Study:

• To characterize a novel group of conjugative plasmids identified in Pseudomonas.
• To investigate the genetic features, diversity, and potential adaptive functions of these plasmids.
• To explore the evolutionary relationships and dissemination mechanisms of these novel plasmids.

Main Methods:

• Plasmid DNA isolation and characterization from Pseudomonas strains.
• Whole-genome sequencing and bioinformatic analysis of plasmid sequences.
• Comparative genomics to identify homologous regions and accessory gene content.
• In silico analysis of predicted gene functions and plasmid replication mechanisms.

Main Results:

• Identification and characterization of the prototype plasmid pPPUT-Tik1-1 (153,663 bp) from a permafrost P. putida strain.
• Discovery of homologous backbone regions in ten other plasmids and 34 contigs in GenBank, with two nearly identical plasmids from clinical strains.
• A unique replication system with two genes (repA1 and repA2) not related to known incompatibility groups was identified.
• Significant variation in accessory regions, including genes for antibiotic resistance, heavy metal tolerance, and xenobiotic degradation.
• Plasmids exhibit a narrow host range within the Pseudomonas genus and shorter variants lacking conjugation genes were observed.
• Evidence suggests conjugation as a primary mechanism for plasmid spread in environmental and clinical Pseudomonas.

Conclusions:

• A novel group of conjugative Pseudomonas plasmids with distinct replication mechanisms and diverse accessory functions has been discovered.
• These plasmids contribute to bacterial adaptation by carrying genes for antibiotic resistance, heavy metal tolerance, and xenobiotic degradation.
• The findings highlight the importance of plasmids in shaping the adaptive potential of Pseudomonas populations in various ecological niches.