%0 Journal Article %J Frontiers in Microbiology %D 2019 %T Influence of environmental drivers and potential interactions on the distribution of microbial communities from three permanently stratified Antarctic lakes %A Li, Wei %A Rachael M. Morgan-Kiss %K Aquatic protists %K environmental drivers %K heterotrophic bacteria %K interactions %K McMurdo Dry Valley lakes %X

The McMurdo Dry Valley (MDV) lakes represent unique habitats in the microbial world. Perennial ice covers protect liquid water columns from either significant allochthonous inputs or seasonal mixing, resulting in centuries of stable biogeochemistry. Extreme environmental conditions including low seasonal photosynthetically active radiation (PAR), near freezing temperatures, and oligotrophy have precluded higher trophic levels from the food webs. Despite these limitations, diverse microbial life flourishes in the stratified water columns, including Archaea, bacteria, fungi, protists, and viruses. While a few recent studies have applied next generation sequencing, a thorough understanding of the MDV lake microbial diversity and community structure is currently lacking. Here we used Illumina MiSeq sequencing of the 16S and 18S rRNA genes combined with a microscopic survey of key eukaryotes to compare the community structure and potential interactions among the bacterial and eukaryal communities within the water columns of Lakes Bonney (east and west lobes, ELB, and WLB, respectively) and Fryxell (FRX). Communities were distinct between the upper, oxic layers and the dark, anoxic waters, particularly among the bacterial communities residing in WLB and FRX. Both eukaryal and bacterial community structure was influenced by different biogeochemical parameters in the oxic and anoxic zones. Bacteria formed complex interaction networks which were lake-specific. Several eukaryotes exhibit potential interactions with bacteria in ELB and WLB, while interactions between these groups in the more productive FRX were relatively rare.

%B Frontiers in Microbiology %V 10 %8 05/2019 %G eng %U https://www.frontiersin.org/articles/10.3389/fmicb.2019.01067/full %! Front. Microbiol. %R 10.3389/fmicb.2019.01067 %0 Journal Article %J Polar Biology %D 2017 %T Impact of nitrogen and phosphorus on phytoplankton production and bacterial community structure in two stratified Antarctic lakes: a bioassay approach %A Teufel, Amber G. %A Li, Wei %A Kiss, Andor J. %A Rachael M. Morgan-Kiss %K Algal–bacteria interactions %K climate change %K McMurdo Dry Valleys %K Nutrient bioassay %K Primary production %X

Arctic, Antarctic, and alpine ecosystems are recognized as sensors and sentinels of global change. As a consequence of their high sensitivity to minor climatic perturbations, permanently ice-covered lakes located in the McMurdo Dry Valleys (MDV), Antarctica, represent end members in the global network of inland bodies of water. Episodic climatic events in the form of increased summer glacial melt result in inputs of organic sediment and nutrients from glacial streams to these closed basins. Phytoplankton communities residing in the oligotrophic water columns are highly responsive to pulses in nutrient availability; however, there is a lack of understanding on whether specific phytoplankton groups are more competitive during a summer flood event and how shifts in the phytoplankton community may influence heterotrophic bacteria. A bioassay approach in 3-l bottles was used to investigate the influence of inorganic nitrogen and phosphorus availability on planktonic communities from the oligotrophic upper waters of two chemically distinct MDV lakes (Lakes Bonney and Fryxell) which differ in their external inputs and water column N/P stoichiometry. While microbial community responses varied between lakes and were nutrient-dependent, stimulation of phytoplankton biomass and productivity across all treatments was strongly linked with increased abundance of a single phytoplankton phylum (Chlorophyta). Despite stimulation of phytoplankton growth, primary and bacterial productivity was generally uncoupled; however, shifts in bacterial community diversity were observed in bioassays amended with either P or NP. We suggest that climate-associated increases in phytoplankton production and concomitant shifts in diversity will influence MDV bacterial community structure by altering the availability and composition of autochthonous carbon for heterotrophic production.

%B Polar Biology %V 40 %8 05/2017 %G eng %U https://link.springer.com/article/10.1007/s00300-016-2025-8 %N 5 %! Polar Biol %& 1007 %R 10.1007/s00300-016-2025-8 %0 Thesis %B Department of Microbiology %D 2016 %T Influence of environmental drivers and interactions on the microbial community structures in permanently stratified meromictic Antarctic lakes %A Li, Wei %A Rachael M. Morgan-Kiss %X

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.

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.

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.

%B Department of Microbiology %I Miami University %C Oxford, OH %V Ph.D. %8 2016 %G eng %U http://rave.ohiolink.edu/etdc/view?acc_num=miami1469757316 %9 doctoral