Recombination and microdiversity in coastal marine cyanophages

Document Type

Article

Publication Title

Environmental Microbiology

Publication Date

11-1-2009

Abstract

Genetic exchange is an important process in bacteriophage evolution. Here, we examine the role of homologous recombination in the divergence of closely related cyanophage isolates from natural marine populations. Four core-viral genes (coliphage T4 homologues g20, g23, g43 and a putative tail fibre gene) and four viral-encoded bacterial-derived genes (psbA, psbD, cobS and phoH) were analysed for 60 cyanophage isolates belonging to five Rhode Island Myovirus (RIM) strains. Phylogenetic analysis of the 60 concatenated sequences revealed well-resolved sequence clusters corresponding to the RIM strain designations. Viral isolates within a strain shared an average nucleotide identity of 99.3-99.8%. Nevertheless, extensive microdiversity was observed within each cyanophage strain; only three of the 60 isolates shared the same nucleotide haplotype. Microdiversity was generated by point mutations, homologous recombination within a strain, and intragenic recombination between RIM strains. Intragenic recombination events between distinct RIM strains were detected most often in host-derived photosystem II psbA and psbD genes, but were also identified in some major capsid protein g23 genes. Within a strain, more variability was observed at the psbA locus than at any of the other seven loci. Although most of the microdiversity within a strain was neutral, some amino acid substitutions were identified, and thus microdiversity within strains has the potential to influence the population dynamics of viral-host interactions. © 2009 Society for Applied Microbiology and Blackwell Publishing Ltd.

Volume

11

Issue

11

First Page

2893

Last Page

2903

DOI

10.1111/j.1462-2920.2009.02037.x

ISSN

14622912

E-ISSN

14622920

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