Wednesday 04 November 2015 at 3:00pm

Title: “To Kill or Not to Kill, a Phage Tale”

Speaker:
Dr. Feng Chen, UMCES-IMET

Abstract:
Viruses are the most abundant biological entities in the biosphere, and they typically outnumber bacteria by an order of magnitude. The vast majority of viruses in the sea are bacteriophage which infect bacterial communities. Virulent phage, mild phage and prophage have been found in bacteria. However, it is not clear how these different types of phage interact with bacteria with different ecological strategies (i.e. specialist vs. generalist, or K-selected vs. r-selected). To understand if bacterial populations involve different virus-host interactions, we focus on two major marine bacterial populations, photoautotrohic cyanobacteria Synechococcus (specialists) and heterotrophic bacteria in the Roseobacter lineage (generalists). We isolated and characterized many phages which infect both Synechococcus spp. and roseobacters, and compared the genomic features of phages and hosts. We found that lytic infection prevails among cyanobacteria, while mild infection and 'symbiotic' prophage are common in roseobacters. Roseobacters are usually versatile microorganisms which can respond quickly to environmental changes. Nearly all roseobacters carry a phage-like element called gene transfer agent (GTA). GTA is an interesting feature among roseobacters and is believed to play an important role for genomic diversification of roseobacters. In addition, many roseobacters contain intact or inducible prophages. Genomes of marine picocyanobacteria do not contain intact prophage and GTA. The accumulating evidence support that these two bacterial populations adopt different virus-host strategies. To kill or not to kill appears to be selected by ecological evolution and adaptation of bacterial populations.

Host: TBD