Jin, QushengWu, Qiong2021-11-232021-11-23https://hdl.handle.net/1794/26901Microbial kinetics study on the microbial metabolic rates and their dependence on biological and environmental conditions. It has been widely used in biogeochemical models. However the empirical nature of microbial kinetics masks the mechanisms of growth kinetic parameters and challenges the applicability to natural environments. Whereas metabolism analysis can heal reveal the mechanism how enzymatic kinetics affect the microbial kinetics. Thus it is necessary to bridge the gap between microbial kinetics and cell metabolism. We firstly implemented cell metabolism of a model methanogen which can utilize a spectrum of substrates to produce methane gas. We validated the model and explored the mechanisms of resource allocation. We then focus on the metabolism of methanol methanogenesis. The simulation results in methanol concentrations ranging from 0.001 mM to 100 mM, proteome allocation shows a trade-off between growth related sector and methanogenesis sector. In addition, the model results link the rate-law parameters to kinetically-influential enzymes, and illustrate the plasticity and trade-off of the parameters as a manifestation of cellular resource allocation. Then we apply the microbial kinetics by integrating the physiological acclimation to individual functional group of acetoclastic methanogen including Methanosarcina and Methanosaeta species. Current models usually treat microbes as auto catalysts, and couple methane production to cell growth by using rate laws and constant kinetics parameters. However, microbes are capable of acclimating and adapting to ambient environment by modulating kinetic properties. Here, we constructed an acclimation model to describe the variations of methanogenesis parameters with substrate concentrations and thermodynamic conditions, as experienced by microbes in environments of different trophic status. Our results show that modeling microbes as a self-adapting catalyst is critical for predicting methanogenesis kinetics. At last, we applied microbial kinetics to microbial communities to study the temperature sensitivity of anaerobic organic matter decomposition. The model framework included the transition from soil organic matter to dissolved organic matter by extracellular enzymes, fermentation, acetoclastic and hydrogenotrophic methanogenesis by fermenters and methanogens. We applied the enzyme-assisted Arrhenius, Cardinal temperature equations and Monod equation to explore the temperature sensitivity of microbial kinetics. Results show that fermentation is the bottleneck of the anaerobic organic matter degradation.en-USAll Rights Reserved.biogeochemical reaction modellingmethanogenesismicrobial acclimationmirobial adaptationmirobial traitsElectronic Thesis or Dissertation