Downloaded from www.microbiologyresearch.org by IP: 54.70.40.11 On: Tue, 30 Oct 2018 05:52:04 Evidence of bacteriophage-mediated horizontal transfer of bacterial 16S rRNA genes in the viral metagenome of the marine sponge Hymeniacidon perlevis Catriona Harrington, 1,2,3 Antonio Del Casale, 3 Jonathan Kennedy, 1 Horst Neve, 4 Bernard E. Picton, 5 Marlies J. Mooij, 1,2,6 Fergal O’Gara, 1,2,6 Leonid A. Kulakov, 3 Michael J. Larkin 3 and Alan D. W. Dobson 1,2 Correspondence Alan D. W. Dobson a.dobson@ucc.ie Received 9 February 2012 Revised 30 May 2012 Accepted 15 August 2012 1 Marine Biotechnology Centre, Environmental Research Institute, University College Cork, Cork, Ireland 2 Department of Microbiology, University College Cork, Cork, Ireland 3 School of Biological Sciences, The Queen’s University of Belfast, UK 4 Department of Microbiology and Biotechnology, Max Rubner-Institute, Federal Research Institute for Nutrition and Food, Kiel, Germany 5 Department of Natural Sciences, National Museums Northern Ireland, Ireland 6 BIOMERIT Research Centre, Microbiology Department, University College Cork, Cork, Ireland Marine sponges have never been directly examined with respect to the presence of viruses or their potential involvement in horizontal gene transfer. Here we demonstrate for the first time, to our knowledge, the presence of viruses in the marine sponge Hymeniacidon perlevis. Moreover, bacterial 16S rDNA was detected in DNA isolated from these viruses, indicating that phage- derived transduction appears to occur in H. perlevis. Phylogenetic analysis revealed that bacterial 16S rDNA isolated from sponge-derived viral and total DNA differed significantly, indicating that not all species are equally involved in transduction. INTRODUCTION Viruses are the most numerous and diverse biological entities in not only the marine environment, with 10 6 to 10 9 particles (ml seawater) 21 (Kristensen et al., 2010) and 10 30 unique viral genotypes (Suttle, 2007), but also on Earth (Angly et al., 2006). Viruses are extremely important life forms known to play a crucial role in microbial ecosystems. They are essential for maintaining and influencing the diversity of all microbial communities both by affecting them directly (by controlling numbers of bacterial cells) and by horizontally transferring genetic material to the host via the transduction process (Lohr et al., 2005). Phages can also affect microbial evolution as killing certain dominant bacteria may allow other related strains that are resistant to the phage to become dominant (Angly et al., 2006) in what is known as the ‘kill the winner’ hypothesis. This may help explain microbial diversity and the changes that can be observed within bacterial community composition (Rohwer et al., 2009). However, this interaction between phages and their bacterial hosts has remained largely under studied, especially with respect to marine sponge ecosystems. Microbial communities of marine sponges are a major focus of current research, as sponge-associated microbes have been shown to produce a plethora of novel bioactive metabolites (Taylor et al., 2007). Due to the advent of high throughput sequencing, numerous metagenomic studies have facilitated the identification of sponge-associated bacterial groups, which have revealed remarkable levels of bacterial diversity, with 26 major phyla to date having been found to be present in close association with sponge species worldwide (Kennedy et al., 2008; Webster & Taylor 2012; Jackson et al., 2012). Some sponges have a low microbial abundance, with a microbial range similar to that of Abbreviations: CRISPR, clustered regularly interspaced short pal- indromic repeat; OTU, operational taxonomic unit; TEM, transmission electron microscopy; TFF, tangential flow filtration. The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequences from viral DNA retrieved from seawater and from H. perlevis in June 2010 are JQ435953–JQ435983 and JQ435984–JQ436010, respectively. Two supplementary figures are available with the online version of this paper. Microbiology (2012), 158, 2789–2795 DOI 10.1099/mic.0.057943-0 057943 G 2012 SGM Printed in Great Britain 2789