Exploring The Relationship Between Biological Complexity, Spatial Heterogeneity And Process Rates In A Genome-informed Reactive Transport Model.

Abstract:

Reactive transport models are critical tools for the prediction of biogeochemical process rates relevant to terrestrial and aquatic ecosystem function as well as contaminant mobility and bioavailability. As these models increase in process complexity, an important challenge involves quantifying the consequences of added complexity for fundamental emergent phenomena such as the processing of exergy and entropy production. The rates of these phenomena emerge from the assembly of complex biogeochemical networks that include the chemical species, the microbial catalysts and feedbacks within porous media that may also be governed by physical/chemical heterogeneity. Here we explore the relationships between the parameterization of microbial kinetics, the complexity of a reaction network, the complexity of microbial catalysts and the heterogeneity of a porous medium using the reactive transport code ‘BioCrunch’. BioCrunch was developed from CrunchFlow to explicitly represent microbes using ‘omics-derived information. Energy allocation schemes within BioCrunch allow a dual-Monod type approach to simulate redox thermodynamics of microorganisms and the resulting fractionation of resources for cellular maintenance, respiration, biomass growth, and enzyme production. We have developed an allometric scaling approach to parameterize microbial reaction kinetics based on prediction of cell volumes, and a workflow to assign microbial genomes to specific reactions within a network. In this presentation we will show how complexity at the enzyme (kinetics), microorganism (linkage of reaction pathways), and community (hyperdimensional trait representation) influences exergy destruction and entropy production. Results of simulations representing interactions between C, N, S, Fe biogeochemistry associated with organic matter hotspots in porous media shows that entropy production rate is related to biological complexity as well as spatial and temporal factors that create heterogeneity and facilitate niche construction. In this context, reactive transport models that incorporate biological complexity across scales are emerging as valuable tools to interpret both biogeochemical and ecological processes.