Research

The Thrash lab is oriented around testing hypotheses about the relationships among and between microorganisms and their environment, particularly in aquatic systems. We combine cultivation independent methods (e.g., metagenomics, metatranscriptomics, and single-cell genomics) with high throughput culturing, physiology, and microbial genomics, as well as chemical and physical information from the environment to piece together why microorganisms occur where they do and why. See our Publications page to get a sense of our recent work.

High throughput culturing

workflowWe have systematically collected samples from across the Southern Louisiana coastline and collaborated with other researchers in marine and freshwater environments to conduct high throughput cultivation (HTC) experiments using tailored, defined media. We also collect water chemistry and microbial communities data from the source water to evaluate cultivation efficacy and refine our defined media recipes. To date, we have isolated over 400 microorganisms, 43% of which occur within the top 50 most abundant taxa in the sampled environments. Prominent examples include the first isolation of a freshwater SAR11 (a.k.a. LD12) representative, members of SAR11 subclade IIIa, OM43, OM182, SAR92, SAR116, Limnohabitans, Polynucleobacter, Actinobacter acIV, and many others. See our culture collection page for a comprehensive list.

Associated funding:
“A Microbial High Throughput Culturing Laboratory at LSU.” Louisiana Board of Regents Research Competitiveness Subprogram

Associated Publications:
Henson, Michael W.,  V. Celeste Lanclos, and J. Cameron Thrash. (2017) Insights on the importance of salinity from the first cultured freshwater SAR11 (LD12) representative. Submitted. bioRxiv preprint. Supplementary Information.

Henson, Michael W., David M. Pitre, Jessica Lee Weckhorst, V. Celeste Lanclos, Austen T. Webber, and J. Cameron Thrash. (2016) Artificial seawater media facilitates cultivating members of the microbial majority from the Gulf of Mexico. mSphere 1(2). doi: 10.1128/mSphere.00028-16. (Undergraduate authors) Supplementary Information.

Lanclos, V. Celeste, Michael W. Henson, David M. Pitre, and J. Cameron Thrash. (2016) Draft Genome Sequence of strain LSUCC0135, an early diverging member of the Methylophilales in the Betaproteobacteria. Genome Announcements. 4(6):e01231-16. (Undergraduate authors)

Thrash, J. Cameron, Jessica Lee Weckhorst and David M. Pitre. (2015) Cultivating Fastidious Microbes. In Hydrocarbon and Lipid Microbiology Protocols, vol. 4 (Cultivation). Edited by Terry J. McGenity, Kenneth N. Timmis and Balbina Nogales. In Press. (Undergraduate authors)

Evolution of salinity tolerance in SAR11

During 2018-2019, in collaboration with Liz Kujawinski (WHOI) we will be quantifying the mechanistic differences between sister clades of SAR11 that have evolved to inhabit environments of with very different ionic strength regimes. Stay tuned for more!

tree_growth_ecol

Associated Funding:
“Collaborative Research: EAGER: Salinity-based selection between sister clades of abundant coastal bacterioplankton.” National Science Foundation OCE-1747681

Microbial ecology of the northern Gulf of Mexico “dead zone” 

GoM_ESOM_binsWe collaborate with Nancy Rabalais (LSU/LUMCON), Olivia Mason (Florida State University), and Brett Baker (University of Texas) in deploying a wide range of cultivation-independent techniques to learn about the microbial communities and genetics associated with the generation and maintenance of seasonal bottom water hypoxia on the Northern Gulf of Mexico shelf region (see lab blog entries for 2013 and 2014 cruise information).

Associated Funding:
“Cultivation independent assessment of microbial communities in the Gulf of Mexico dead zone.” Ralph E. Powe Junior Faculty Enhancement Award, Oak Ridge Associated Universities.

Associated Publications:
Thrash, J. Cameron , Kiley W. Seitz, Brett J. Baker, Ben Temperton, Lauren E. Gillies, Nancy N. Rabalais, Bernard Henrissat, Olivia U. Mason. (2017) Metabolic roles of uncultivated bacterioplankton lineages in the northern Gulf of Mexico “Dead Zone” mBio. 8(5):e01017-17. bioRxiv preprintSupplementary Information.

Gilles, Lauren E., J. Cameron Thrash, Sergio deRada, Nancy N. Rabalais, and Olivia U. Mason. (2015) Archaeal enrichment in the hypoxic zone in the northern Gulf of Mexico. Environmental Microbiology. 17(10): 3847-3856.

Microbial ecology of the Mississippi River

Mpa copy 2We have been coordinating with OAR Northwest in a citizen science and education program to explore the microbial assemblages inhabiting the Mississippi River and begin quantifying their relationship to eutrophication. To date, we have completed two full-length Mississippi River transects using rowboats, and are in the process of publishing our results. You can read more about the science HERE and watch a promotional video from the 2014 season:

Associated Publications:
Henson, Michael W., Jordan Hanssen, Greg Spooner, Patrick Flemming, Markus Pukonen,  Frederick Stahr, and J. Cameron Thrash. (2017) Nutrient dynamics and stream order influence microbial community patterns along a 2914 km transect of the Mississippi River. Submitted. bioRxiv preprint. Supplemental Information.

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