Viral Induced Microbial Mortality in Arctic Hypersaline Spring Sediments.
Viruses are a primary influence on microbial mortality in the global ocean. The impacts of viruses on their microbial hosts in low-energy environments are poorly explored and are the focus of this study. To investigate the role of viruses in mediating mortality in low-energy environments where contacts between viruses and microbes are infrequent, we conducted a set ofin situtime series incubations in the outlet and channel sediments of two cold, hypersaline springs of the Canadian High Arctic. We found microbial and viral populations in dynamic equilibrium, indicating approximately equal birth and death rates for each population.In siturates of microbial growth were low (0.5-50 × 103cells cm-3h-1) as were rates of viral decay (0.09-170 × 104virions cm-3h-1). A large fraction of the springs' viral communities (49-100%) were refractory to decay over the timescales of our experiments. Microcosms amended with lactate or acetate exhibited increased microbial growth rates (up to three-fold) indicating organic carbon as one limiting resource for the microbial communities in these environments. A substantial fraction (15-71%) of the microbial populations contained inducible proviruses that were released- occasionally in multiple pulses- over the eight monitored days following chemical induction. Our findings indicate that viruses in low-energy systems maintain low rates of production and activity, have a small but notable impact on microbial mortality (8-29% attenuation of growth) and that successful viral replication may primarily proceed by non-lethal strategies. In cold, low biomass marine systems of similar character (e.g., subsurface sediments), viruses may be a relatively minor driver of community mortality compared to less energy-limited environments such as the marine water column or surface sediments.
Department of Earth and Planetary Science, McGill University, MontrealQC, Canada; McGill Space Institute, McGill University, MontrealQC, Canada.
Jesse
J
Colangelo-Lillis
Department of Earth and Planetary Science, McGill University, MontrealQC, Canada; McGill Space Institute, McGill University, MontrealQC, Canada.
Boswell A
BA
Wing
Department of Natural Resource Science, McGill University, Montreal QC, Canada.
Isabelle
I
Raymond-Bouchard
McGill Space Institute, McGill University, MontrealQC, Canada; Department of Natural Resource Science, McGill University, MontrealQC, Canada.
Lyle G
LG
Whyte
hypersaline sediments; lysogeny; oligotrophy; polar microbial ecology; viral dynamics