Impacts of diel light intensity changes on marine microbial life in productive ocean communitiesOur current understanding of the complex and dynamic ocean ecosystem is limited due to single time of day sampling “snapshots”. Therefore, to examine how light/temperature and other daily variant conditions impact microbial communities in ocean waters, the lab has sampled the productive coastal water at various locations, depths, and times throughout the day (pre-sunrise to post sunset). DNA and RNA from the samples will be examined using high-throughput sequencing techniques to identify the microorganisms present in ocean communities (DNA) and also evaluate the community metabolism (RNA, metatranscriptomics). These data will be applied to determine how the diversity of these communities changes as well as how shifts in gene expression throughout the day are potentially impacting biogeochemical cycles.
Biogeochemistry and microbial community structure in Great Lakes wetlands The biogeochemical cycling of greenhouse gases (such as N2O and CH4) and essential nutrients (e.g. carbon and nitrogen) are catalyzed by a diverse group microorganisms within wetlands. There are greater than 2,000 coastal wetlands in the Laurentian Great Lakes, despite a 50% reduction driven by anthropogenic habitat destruction. In one project, we are exploring these critical ecosystems to better understand the microbial communities and biogeochemical processes they govern. In a second project, we are examining how natural forces, such as diel O2 fluctuations, can impact community structure and function.
Microbial geochemistry of marine sediments from western Antarctica Western Antarctica is currently one of the fastest warming locations on Earth. The melting of the West Antarctic Ice Sheet will alter regional water temperature and salinity. These changes will inevitably impact the microorganisms that inhabit these environments and govern the biogeochemical cycles (e.g. carbon, nitrogen, sulfur) that are essential for this thriving ecosystem. By using next-generation sequencing techniques, this work will define what microorganisms inhabit sediments off the west coast of Antarctica. In addition, metagenomic analysis of these sediments will be able to identify the functional genes that are found in these sediments. Thus, this work will be able to define what organisms are abundant in these locations and also what mechanisms they are using (functional genes) to drive crucial biogeochemical cycles.
Defining novel bacterial Mn(II) oxidation mechanisms Manganese(III,IV) oxide minerals are among the strongest sorbents and oxidants in the environment. Despite the importance of Mn oxides in controlling countless biogeochemical cycles, we have only a vague understanding of the biotic and abiotic pathways responsible for their formation in the environment and the underlying mechanisms involved. We have shown that a common marine bacterium, Roseobacter sp. AzwK-3b, oxidizes Mn(II) to solid phase Mn oxide minerals via the production of extracellular superoxide. Our current work is using a two pronged approach, genetics and proteomics, to determine how R. AzwK-3b generates superoxide and mediates Mn(II) oxidation and the production of Mn oxide minerals.