1. ¹University of Delaware, Graduate College of Marine Studies, Newark, DE, USA
2. ²Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA

Correspondence: KE Wommack, Department of Plant and Soil Sciences and College of Marine Studies, Delaware Biotechnology Institute, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA. E-mail: wommack@dbi.udel.edu

³Current address: J Craig Venter Institute, Microbial and Environmental Genomics, La Jolla, CA, USA.

⁴Current address: Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA.

Received 2 April 2008; Revised 3 July 2008; Accepted 3 July 2008; Published online 21 August 2008.

Abstract

The consequences of viral infection within microbial communities are dependent on the nature of the viral life cycle. Among the possible outcomes is the substantial influence of temperate viruses on the phenotypes of lysogenic prokaryotes through various forms of genetic exchange. To date, no marine microbial ecosystem has consistently shown a predisposition for containing significant numbers of inducible temperate viruses. Here, we show that deep-sea diffuse-flow hydrothermal vent waters display a consistently high incidence of lysogenic hosts and harbor substantial populations of temperate viruses. Genetic fingerprinting and initial metagenomic analyses indicate that temperate viruses in vent waters appear to be a less diverse subset of the larger virioplankton community and that these viral populations contain an extraordinarily high frequency of novel genes. Thus, it appears likely that temperate viruses are key players in the ecology of prokaryotes within the extreme geothermal ecosystems of the deep sea.