Affiliation:
1. Department of Biology, Roger Williams University, Bristol, Rhode Island 02809
2. Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02861
Abstract
ABSTRACT
Marine viruses are an important component of the microbial food web, influencing microbial diversity and contributing to bacterial mortality rates. Resistance to cooccurring cyanophages has been reported for natural communities of
Synechococcus
spp.; however, little is known about the nature of this resistance. This study examined the patterns of infectivity among cyanophage isolates and unicellular marine cyanobacteria (
Synechococcus
spp.). We selected for phage-resistant
Synechococcus
mutants, examined the mechanisms of phage resistance, and determined the extent of cross-resistance to other phages. Four strains of
Synechococcus
spp. (WH7803, WH8018, WH8012, and WH8101) and 32 previously isolated cyanomyophages were used to select for phage resistance. Phage-resistant
Synechococcus
mutants were recovered from 50 of the 101 susceptible phage-host pairs, and 23 of these strains were further characterized. Adsorption kinetic assays indicate that resistance is likely due to changes in host receptor sites that limit viral attachment. Our results also suggest that receptor mutations conferring this resistance are diverse. Nevertheless, selection for resistance to one phage frequently resulted in cross-resistance to other phages. On average, phage-resistant
Synechococcus
strains became resistant to eight other cyanophages; however, there was no significant correlation between the genetic similarity of the phages (based on
g20
sequences) and cross-resistance. Likewise, host
Synechococcus
DNA-dependent RNA polymerase (
rpoC1
) genotypes could not be used to predict sensitivities to phages. The potential for the rapid evolution of multiple phage resistance may influence the population dynamics and diversity of both
Synechococcus
and cyanophages in marine waters.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
67 articles.
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