Abstract

Dormancy is a plausible strategy for bacteria to overcome the effects of temporal fluctuations in resources or stresses and await more “optimal” conditions to resume metabolic activity and growth. Seasonal changes in environmental conditions force microbes to adjust their metabolic activity accordingly, and community composition drastically shifts. In extreme environments, however, the overriding effects of a constant stress may constrain the need or benefit of bacteria entering dormancy. In hypersaline lakes, high metabolic activity is required to maintain adaptations that permit survival. Sampling from six lakes on a salinity gradient (0.05% – 30.3%), we measured seasonal fluctuations in bacterial dormancy patterns in summer, fall, winter, and spring of 2013-14. Dormancy was calculated based on ratios of OTU recovery between 16S rRNA-based communities (only the active bacteria) and 16S rRNA gene-based communities (all bacteria present in the community) from lake water. Dormancy was linked to lake chemistry shifts through time. We found that salinity was strongly related to relative bacterial dormancy. There was a negative linear relationship (R2 = .89 P <0.01) between total dormancy and salinity. Total phosphorus (R2 = .63, P < .001) and relative community contribution by rare taxa (R2 = .89, P < .001) were also important in structuring dormancy. Our findings suggest that temporal nutrient flux is highly influential on bacterial community composition and activity, but that the presence of an extreme variable decreases change in both through time.

Degree

College and Department

Life Sciences; Microbiology and Molecular Biology

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