Project Details
Projekt
Impact of salinity changes on viral production during the paleoenvironmental history of Baltic Sea sediments
Applicants
Privatdozent Dr. Bert Engelen; Dr. Verona Vandieken
Subject Area
Palaeontology
Microbial Ecology and Applied Microbiology
Microbial Ecology and Applied Microbiology
Term
from 2014 to 2019
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 260992344
Deep subsurface sediments of the Baltic Sea represent a paleoenvironmental archive of this intra-continental basin which has undergone alterations between limnic, brackish and marine conditions in the past. The aim of IODP Exp. 347 has been to investigate the impact of these environmental changes on benthic microbial communities. As viruses control microbial populations and mediate carbon turnover due to lysis of infected cells, they have a major impact on microbial and biogeochemical processes. In the first funding period, we have started to analyze viruses and their host bacteria as numerous and active components of the deep biosphere. For fast and accurate counting of viruses in culture media, we have developed a protocol for flow cytometry that can now be used for a large number of samples which will be adapted for counting viruses in sediments. From our cultivation experiments, we have obtained 36 isolates; some of them will be validly described as new species or even genera. Physiological analysis revealed considerable differences in their salinity tolerance. Different viruses have been identified in the isolates, which are either induced by the antibiotic mitomycin or produced at high numbers during growth of the bacteria. In the proposed project, we will establish a database of phage genomes from our isolates which will possibly reveal viral features important for the persistence in the deep biosphere and alleviate the identification of specific phages in e.g. metagenomes or single-cell genomes from the deep biosphere. Furthermore, our current studies on osmotic shock as an inducer for virus production will be extended from pure cultures to environmental samples. Analyzing microbial community structures and organic carbon composition during cell lysis and subsequent uptake of cell material by opportunistic bacteria will help to understand the role of viruses during the paleoenvironmental history of the Baltic Sea.
DFG Programme
Infrastructure Priority Programmes
