Stoichiometric modeling focuses on the balance of elements and energy within a system. The idea is to use microscopic approach to explain macroscopic phenomena. There is widespread empirical evidence that protist grazing on bacteria reduces bacterial abundances but increases bacteria-mediated decomposition of organic matter. This paradox has been noted repeatedly in the microbiology literature but lacks a generally accepted mechanistic explanation. To explain this paradox quantitatively, we develop a bacteria-grazer model of organic matter decomposition that incorporates protozoa-driven nutrient recycling and stoichiometry. Model analysis reveals that facilitation of organic matter decomposition by grazers is positively related to the stoichiometric difference between bacteria and grazers. In addition, we predict the existence of an optimal density range of introduced grazers, which maximally facilitate the decomposition of organic matter in a fixed time period. This optimal range reflects a trade-off between grazer-induced nutrient recycling and grazer-induced mortality of bacteria. The second part of the talk is a natural extension of the above model in a chemostat culture to mimic some real applications. We perform persistence and bifurcation analysis and explore the impact of the dilution rate on biodegradation. In the last part of the talk, I will discuss our new collaboration with oil sands researchers confronting our stoichiometric biodegradation models with ongoing experimental data.

 

报告人简介:  Dr. Hao Wang is currently a tenured faculty member at the University of Alberta. He is an editor/associate editor/regional editor for several journals in United States and Europe. Dr. Hao Wang’s research program is truly interdisciplinary at the interface of mathematical, computational, and experimental studies. His research focuses on differential equations and their applications in life sciences, and is leading several interdisciplinary modeling projects on estimation and reduction of greenhouse gas emissions from biodegradation in oil sands industry, impacts of industrial toxins on ecosystems.