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Research

Microbial Community Plastic Bioremediation and Upcycling

Each year approximately 300 million tons of plastic waste is generated. Only 9% of this waste is effectively recycled, with the remainder ending up in landfills where natural plastic degradation is exceedingly slow. Because plastics are composed of complex polymers they break down slowly in the natural environment via biotic and abiotic processes.  

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This work aims to combine chemical and biological processes of plastic breakdown in order to increase the speed and efficiency with which we can breakdown plastic products.

Chemical deconstruction of plastics breaks down complex plastic polymers into smaller and less complex molecules that are more bioavailable. These breakdown products are then provided to microbial consortia that are capable of utilizing these compounds to grow and generate biomass whilst further breaking down the deconstructed plastic products.   

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I am working to understand the compositional and functional stability of microbial consortia growing on these products so we can enhance the speed and efficiency of deconstructed plastic breakdown in this system. Additionally, I am working to characterize the metabolic by-products created by these consortia to assess their toxicity and determine the feasibility of downstream commercial use of biomass grown on plastic for food products. ​

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​Publications Associated with this work:

  1. Schaerer L., Putman L., Bigcraft I., Byrne E., Kulas D., Zolghadr A., Aloba S., Ong R., Shonnard D., Techtmann S. (2023). Coexistence of specialist and generalist species within mixed plastic derivative‑utilizing microbial communities. Microbiome. doi:10.1186/s40168-023-01645-4

  2. Putman L.I., Schaerer L.G., Wu R., Kulas D.G., Zolghadr A., Ong R.G., Shonnard D.R., Techtmann S.M., Arbanas L.G., Bannerman G.G., Cart B., Cureton A., Doerr B.P., Jovicevic Z., Langosch M., MacLeod A.B., McCloskey C., McNally A.M., Monkevich M.K., Noecker A., Norris D., Pellizzon V.G., Strom K.B., Taylor E.E. (2023). Metagenomic sequencing of two cultures grown on chemically deconstructed plastic products. Microbial Resource Announcements. doi:10.1128/mra.01304-22 

  3. Putman L.I., Schaerer L.G., Wu R., Kulas D.G., Zolghadr A., Ong R.G., Shonnard D.R., Techtmann S.M. (2023). Deconstructed plastic substrate preferences of microbial populations from the natural environment. Microbiology Spectrum. doi:10.1128/spectrum.00362-23

  4. Schaerer, L.G., Wu, R., Putman, L.I., Pearce, J.M., Lu, T., Shonnard, D.R., Ong, R.G., Techtmann, S.M. (2022). Killing two birds with one stone: chemical and biological upcycling of polyethylene terephthalate plastics into food. Trends in Biotechnology. https://doi.org/10.1016/j.tibtech.2022.06.012.

  5. Byrne E., Schaerer L.G., Kulas D.G., Ankathi S.K., Putman L.I., Codere K.R., Schum S.K.,
    Shonnard D.R., Techtmann S.M. (2022). Pyrolysis-Aided Microbial Biodegradation of High-Density
    Polyethylene Plastic by Environmental Inocula Enrichment Cultures. ACS Sustainable Chemistry &
    Engineering. doi:10.1021/acssuschemeng.1c05318

  6. Hubbard B.R., Putman L.I., Techtmann S., Pearce J.M. Open Source Vacuum Oven Design for Low-Temperature Drying: Performance Evaluation for Recycled PET and Biomass. Journal of Manufacturing and Materials Processing, 5(2):52 (2021). https://doi.org/10.3390/jmmp5020052

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Microbial Community Dynamics in Deep Subsurface Groundwaters

Throughout the world, many different factors are challenging the quantity and quality of groundwater resources, including changes in land use, climate, introduction of contaminants, and over-extraction. As groundwater resources become increasingly stressed and drilling activity to access aquifers deep in the subsurface progresses, it is vital to understand how microbial communities in the subsurface change over space and time, and their biogeochemical consequences.

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My dissertation research aimed to describe geochemical and microbial community dynamics within a deep subsurface hard-rock aquifer. Better understanding the dynamics of these valuable groundwater reservoirs will improve our capacity to anticipate changes in the subsurface and manage these valuable water resources in the future. 

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I utilized a 16S rRNA gene amplicon and geochemistry time series dataset performed on fluids collected from a hyperalkaline hard-

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rock aquifer within the Coast Range Ophiolite, CA over a 7-year period. These data were used to assess how physical and geochemical conditions structure observed microbial communities in serpentinizing systems, and to determine how drilling activity to establish the site in 2011 perturbed subsurface geochemical conditions and microbial community composition and function.

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Publications Associated with this work:

  1. Putman L.I., Sabuda M.C., Brazelton W.J., Kubo M.D., Hoehler T.M., McCollom T.M., Cardace D., Schrenk M.O. (2021). Microbial communities in a serpentinizing aquifer are assembled through strong concurrent dispersal limitation and selection. mSystems 6:e00300-21. https://doi.org/10.1128/mSystems.00300-21.

  2. Sabuda M.C., Putman L.I., Hoehler T.M., Kubo M.D., Brazelton W.J., McCollom T.M., Cardace D., Schrenk M.O. Biogeochemical Gradients in a Serpentinization-influenced Aquifer and their Impacts on Greenhouse Gas Flux from the Subsurface. JGR Biogeosciences, 126, e2020JG006209 (2021). https://doi.org/10.1029/2020JG006209

  3. Glombitza, C., Putman, L.I., Rempfert, K.R. et al. Active microbial sulfate reduction in fluids of serpentinizing peridotites of the continental subsurface. Commun Earth Environ 2, 84 (2021). https://doi.org/10.1038/s43247-021-00157-z

  4. Sabuda, M.C., Brazelton, W.J., Putman, L.I., McCollom, T.M., Hoehler, T.M., Kubo, M.D.Y., Cardace, D., and Schrenk, M.O. (2020), A dynamic microbial sulfur cycle in a serpentinizing ophiolite. Environmental Microbiology, 22: 2329-2345. doi:10.1111/1462-2920.15006   

  5. Seyler, L.M., Brazelton, W.J., McLean, C, Putman, L.I., Hyer, A., Kubo, M.D., Hoehler, T.M., Cardace, D., Schrenk, M.O. (2020). Carbon Assimilation Strategies in Ultrabasic Groundwater: Clues from the Integrated Study of a Serpentinization-Influenced Aquifer. mSystems 5:e00607-19. https://doi.org/10.1128/mSystems.00607-19

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