On Single-Cell Enzyme Assays in Marine Microbial Ecology and Biogeochemistry

Journal Article · 24 February 2022 · Frontiers in Marine Science

DOI: https://doi.org/10.3389/fmars.2022.846656 · OSTI ID:1981086

Traving, Sachia J. ^[1]; Balmonte, John Paul ^[2]; Seale, Dan ^[3]; Arnosti, Carol ^[4]; Glud, Ronnie N. ^[5]; Hallam, Steven J. ^[3]; Middelboe, Mathias ^[6]

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1. University of Southern Denmark, Odense (Denmark); University of Copenhagen (Denmark); University of British Columbia, Vancouver, BC (Canada); Univ. of Southern Denmark, Odense (Denmark)
2. University of Southern Denmark, Odense (Denmark)
3. University of British Columbia, Vancouver, BC (Canada)
4. University of North Carolina, Chapel Hill, NC (United States)
5. University of Southern Denmark, Odense (Denmark); Tokyo University of Marine Science and Technology (Japan)
6. University of Southern Denmark, Odense (Denmark); University of Copenhagen (Denmark)

Extracellular enzyme activity is a well-established parameter for evaluating microbial biogeochemical roles in marine ecosystems. The presence and activity of extracellular enzymes in seawater provide insights into the quality and quantity of organic matter being processed by the present microorganisms. A key challenge in our understanding of these processes is to decode the extracellular enzyme repertoire and activities of natural communities at the single-cell level. Current measurements are carried out on bulk or size-fractionated samples capturing activities of mixed populations. This approach – even with size-fractionation – cannot be used to trace enzymes back to their producers, nor distinguish the active microbial members, leading to a disconnect between measured activities and the producer cells. By targeting extracellular enzymes and resolving their activities at the single-cell level, we can investigate underlying phenotypic heterogeneity among clonal or closely related organisms, characterize enzyme kinetics under varying environmental conditions, and resolve spatio-temporal distribution of individual enzyme producers within natural communities. In this perspective piece, we discuss state-of-the-art technologies in the fields of microfluidic droplets and functional screening of prokaryotic cells for measuring enzyme activity in marine seawater samples, one cell at a time. We further elaborate on how this single-cell approach can be used to address research questions that cannot be answered with current methods, as pertinent to the enzymatic degradation of organic matter by marine microorganisms.

• Research Organization: University of California, Oakland, CA (United States); University of North Carolina, Chapel Hill, NC (United States)
• Sponsoring Organization: Canada Foundation for Innovation (CFI); Danish National Research Foundation; National Science Foundation (NSF); Natural Sciences and Engineering Research Council (NSERC); USDOE Office of Science (SC); University of British Columbia
• Grant/Contract Number: AC02-05CH11231; SC0019012
• OSTI ID: 1981086
• Journal Information: Frontiers in Marine Science, Journal Name: Frontiers in Marine Science Vol. 9; ISSN 2296-7745
• Publisher: Frontiers Research FoundationCopyright Statement
• Country of Publication: United States
• Language: English