03056nas a2200133   4500008004100000245014700041210006900188260003900257490001000296520251200306100001202818700002902830856006302859       2016                        eng d00aInfluence of environmental drivers and interactions on the microbial community structures in permanently stratified meromictic Antarctic lakes0 aInfluence of environmental drivers and interactions on the micro  aOxford, OHbMiami Universityc20160 vPh.D.3 a<p>The microbial loop plays important roles in the cycling of energy, carbon and elements in aquatic ecosystems. Viruses, bacteria, Archaea and microbial eukaryotes are key players in global carbon cycle and biogeochemical cycles. Investigating microbial diversity and community structure is crucial first step for understanding the ecological functioning in aquatic environment. Meromictic lakes are bodies of water and exhibit permanent stratification of major physical and chemical environmental factors. Microbial consortia residing in permanently stratified lakes exhibit relatively constant spatial stratification throughout the water column and are adapted to vastly different habitats within the same water. Pristine perennially-ice-covered lakes (Lake Bonney, Lake Fryxell and Lake Vanda) are meromictic lakes located in the McMurdo Dry Valleys (MDV) of Southern Victoria Land, Antarctica. The lakes have isolated water bodies and extremely stable strata that vary physically, chemically, and biologically within and between the water columns. The unique characteristics support microbially dominated food webs in these lakes.</p><p>In the research presented here, we gathered new understanding of how environmental drivers influence microbial community structure in these aquatic ecosystems. We explored the lake microbial ecology from three major approaches: 1). Assess trophic activities in the natural environment and identify potential environmental drivers impacting heterotrophic (β Glucosaminidase) and autotrophic (Ribulose 1,5 bisphosphate carboxylase) enzyme activities; 2). Resolve the protist community composition (i.e. autotrophic, heterotrophic and mixotrophic groups) based on high throughput sequencing and bioinformatics. Identify how the community structures correlate with specific environmental and biological factors; 3). Reveal the diversity of potential microbial interactions between the microorganisms in the MDV lakes at individual cell level, and investigate how the interactions vary between organisms with different nutritional strategies.</p><p>Studies of polar microbial communities on the cusp of environmental change will be important for predicting how microbial communities in low latitude aquatic systems will respond. This study expands the understanding of how environmental drivers interact with microbial communities in the Antarctica lakes, and provide new information to predict how the community structure will alter as response to climate changes.</p>1 aLi, Wei1 aMorgan-Kiss, Rachael, M.  uhttp://rave.ohiolink.edu/etdc/view?acc_num=miami1469757316