GENES IN MOTION · Microbial genes in motion: phage and the nature of lateral gene transfer in freshwater lakes

Freshwater quality was defined as a key environmental theme by the European Environment Agency's State and Outlook 2010 Report. A large threat to freshwater quality is the accelerated eutrophocation of lake waters due to high human impacts from agriculture and industrial and residential wastes, leading to eutrophocation and in some cases toxic cyanobacterial blooms. Microbial communities in eutrophic lakes contribute to a positive feedback loop which perpetuates eutrophocation. The persistence of and capability for dissemination of specific genes related to microbial metabolism in lake environments is unknown. Phage transduction is the primary mechanism by which gene transfer events occur in bacteria. Phage have the possibility to mediate LGT between very distantly related bacteria and transfer virulence factors and genes for metabolic adaptation across taxonomic boundaries and over long phylogenetic ranges. In this study, we will characterise microbial and phage populations as well as phage-mediated LGT in Finnish lakes using culture-independent techniques and high-throughput sequencing to determine: 1) the native microbial and phage populations in lakes at different trophic levels, 2) the cohort of functional genes carried by phage, and 3) how broad the host range of resident phage is. We hypothesize that phage provide a reservoir for genes allowing niche adaptation and increased fitness in response to nutrient stress and/or deprivation. Additionally, we will be able to identify whether phage contribute to the persistence and spread of cyanobacterial toxin genes, and/or providing a reservoir for genes which contribute to the positive feedback loop of eutrophication.