Mathematical simulation of the diel O, S, and C biogeochemistry of a hypersaline microbial mat

K. L.M. Decker, C. S. Potter, B. M. Bebout, D. J. Des Marais, S. Carpenter, M. Discipulo, T. M. Hoehler, S. R. Miller, B. Thamdrup, K. A. Turk, P. T. Visscher

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The creation of a mathematical simulation model of photosynthetic microbial mats is important to our understanding of key biogeochemical cycles that may have altered the atmospheres and lithospheres of early Earth. A model is presented here as a tool to integrate empirical results from research on hypersaline mats from Baja California Sur (BCS), Mexico into a computational system that can be used to simulate biospheric inputs of trace gases to the atmosphere. The first version of our model, presented here, calculates fluxes and cycling of O2, sulfide, and dissolved inorganic carbon (DIC) via abiotic components and via four major microbial guilds: cyanobacteria (CYA), sulfate reducing bacteria (SRB), purple sulfur bacteria (PSB) and colorless sulfur bacteria (CSB). We used generalized Monod-type equations that incorporate substrate and energy limits upon maximum rates of metabolic processes such as photosynthesis and sulfate reduction. We ran a simulation using temperature and irradiance inputs from data collected from a microbial mat in Guerrero Negro in BCS (Mexico). Model O2, sulfide, and DIC concentration profiles and fluxes compared well with data collected in the field mats. There were some model-predicted features of biogeochemical cycling not observed in our actual measurements. For instance, large influxes and effluxes of DIC across the MBGC mat boundary may reveal previously unrecognized, but real, in situ limits on rates of biogeochemical processes. Some of the short-term variation in field-collected mat O2 was not predicted by MBGC. This suggests a need both for more model sensitivity to small environmental fluctuations for the incorporation of a photorespiration function into the model.

Original languageEnglish
Pages (from-to)377-395
Number of pages19
JournalFEMS Microbiology Ecology
Issue number3
StatePublished - May 1 2005


We are indebted to Cynthia Tao for library research and graphics assistance, to Victoria Orphan and Lee Bebout for discussion and feedback on the model system structure and function, and to Rutger de Wit and David Stahl for input on metabolic and growth rate parameters. We are also grateful to an anonymous reviewer for thoughtful and carefully constructed criticism, that helped us improve an earlier version. This project was funded by a grant from the NASA Astrobiology Institute.

FundersFunder number
NASA Astrobiology Institute


    • Biogeochemistry
    • Carbon Microcoleus chthonoplastes
    • Cyanobacteria
    • Microbial mat
    • Modeling
    • Oxygen
    • Sulfur


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