Genomic diversity of bacteriophages infecting Rhodobacter capsulatus and their relatedness to its gene transfer agent RcGTA

PLoS One. 2021 Nov 18;16(11):e0255262. doi: 10.1371/journal.pone.0255262. eCollection 2021.


The diversity of bacteriophages is likely unparalleled in the biome due to the immense variety of hosts and the multitude of viruses that infect them. Recent efforts have led to description at the genomic level of numerous bacteriophages that infect the Actinobacteria, but relatively little is known about those infecting other prokaryotic phyla, such as the purple non-sulfur photosynthetic α-proteobacterium Rhodobacter capsulatus. This species is a common inhabitant of freshwater ecosystems and has been an important model system for the study of photosynthesis. Additionally, it is notable for its utilization of a unique form of horizontal gene transfer via a bacteriophage-like element known as the gene transfer agent (RcGTA). Only three bacteriophages of R. capsulatus had been sequenced prior to this report. Isolation and characterization at the genomic level of 26 new bacteriophages infecting this host advances the understanding of bacteriophage diversity and the origins of RcGTA. These newly discovered isolates can be grouped along with three that were previously sequenced to form six clusters with four remaining as single representatives. These bacteriophages share genes with RcGTA that seem to be related to host recognition. One isolate was found to cause lysis of a marine bacterium when exposed to high-titer lysate. Although some clusters are more highly represented in the sequenced genomes, it is evident that many more bacteriophage types that infect R. capsulatus are likely to be found in the future.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics*
  • Bacteriophages / genetics*
  • Gene Expression Regulation, Bacterial*
  • Gene Transfer Techniques
  • Genetic Variation*
  • Rhodobacter capsulatus / virology*


  • Bacterial Proteins

Grants and funding

The research of JTB was supported by a grant (RGPIN 2018-03898) from the Canadian Natural Sciences and Engineering Research Council (NSERC). The research of DWB was supported by funds from the Illinois Wesleyan University Miner Linnaeus Sherff endowed professorship in Botany. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.