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Virus dynamics in a large epishelf lake ( B eaver L ake, A ntarctica)
Author(s) -
LaybournParry Johanna,
Anesio Alexandre M.,
Madan Nanette,
Säwström Christin
Publication year - 2013
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/fwb.12146
Subject(s) - temperature gradient gel electrophoresis , lysogenic cycle , biology , chlorophyll a , nutrient , lytic cycle , bacteria , virus , food science , chemistry , microbiology and biotechnology , ecology , bacteriophage , botany , biochemistry , escherichia coli , 16s ribosomal rna , virology , genetics , gene
Summary Virus concentrations, virus‐to‐bacterium ratios ( VBR s) and levels of lysogenic phage were measured throughout the 110‐m water column of epishelf B eaver L ake during the austral summer of 2003/2004. The aim was to determine which factor(s) controlled viral dynamics using detailed concomitant published data on inorganic nutrients, chlorophyll a , dissolved organic carbon ( DOC ) and bacterial production for B eaver L ake ( F reshwater B iology , 51, 2006, 1119). Denaturing Gradient Gel Electrophoresis (DGGE) analysis of the bacterial community was also undertaken to investigate the potential relationship between bacterial community composition and viral dynamics. Virus concentration ranged between 1.43 × 10 4 and 302.4 × 10 4 viruses mL −1 and showed a clear increase over the summer, while bacterial concentrations exhibited no seasonal pattern (range: 9.6 × 10 4 to 44.6 × 10 4 cells mL −1 ). Consequently, VBR varied with highest values in J anuary (3.32–7.33). The percentage of lysogenic phage was low, ranging from 0 to 11.69%, suggesting that other life cycles (i.e. lytic or possibly pseudolysogeny) were taking place. Attempts to measure viral production using both the T d R incorporation technique and the dilution technique failed to produce consistent results, in common with other ultra‐oligotrophic A ntarctic lakes. There were significant correlations between viral concentration and each of chlorophyll a , DOC , ammonium and nitrate concentrations and bacterial production, but not between bacterial abundance and either soluble reactive phosphorus or temperature. Lack of change in the dominant bacterial community composition over summer suggests that changes in viral concentrations were a function of changes in other biological and physicochemical factors, rather than changes in host/phage infection. The results suggest a significant connection between viruses and bacteria, with the DOC pool acting as a conduit for the movement of carbon between the two components.