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Seminar Details

Living inside a ‘black hole’: Dynamics of microbe-phage interactions within sponge-associated communities and compared to their planktonic counterparts

Date

10/05/2018

Lecturers

Ilia Burgsdorf - Leon H. Churney School of Marine Sciences, University of Haifa

Abstract

Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel Phages have a huge impact on the composition and behavior of microbial communities in every ecological setting. Phages can affect the evolution of the host in different ways including transduction of novel genes, maintain biodiversity, influencing cellular evolution et cetera. Besides direct influence on the host evolution, phages might take a regulatory part in complex tripartite symbiotic relations, an example from the field of entomology being symbioses between eukaryote, cellular microorganism and phage where the abundance of bacterial symbionts is controlled by phages. Similar complex interactions might exist in marine organisms. Sponges filter large quantities of planktonic microbes, and act as oceanic 'black holes' consuming bacteria, dissolved organic matter and viruses. Thus sponge-associated bacteria are likely exposed to many more viral particles than their free-living counterparts. Previous metagenomic studies revealed that Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) and restriction modification defense mechanisms are abundant features in sponge microbial metagenomes providing indirect evidence for a higher phage-pressure in sponge associated microbiomes. During my study I sampled viral and microbial fractions of the Red Sea sponge Theonella swinhoei. Prior to sponge sampling, the planktonic microbial and viral fractions were collected in the same sampling site. My study will test the connectivity of the sponge holobiont with the ambient planktonic bacterial and phage communities. I will estimate horizontal gene transfer mediated by phages within the sponge associated community and between sponge and planktonic microbial communities. Genomic links between viruses and their microbial hosts will be identified by matching CRISPR loci spacer sequences with viral contigs. I expect to find evidences, that planktonic phages infect sponge-associated bacteria. Consequently, planktonic phages will have a one directional influence on the host-associated bacteria. I will try to assess whether phages may function as part of a tripartite symbiotic interaction (sponge-bacteria-phage) and contain a reservoir of the genes related to symbiosis (auxiliary genes).

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