REGULATION OF MICROBIAL ACTIVITY AND SOIL ORGANIC MATTER DECOMPOSITION IN RESPONSE TO RESOURCES AVAILABILITY BY OPTIMIZING ENZYME ALLOCATION: AN OMICS-INFORMED MODEL STUDY
This study aims to represent the omics-informed optimal foraging theory in the Continuum Microbial ENzyme Decomposition model (CoMEND). The SOM pools in the model are classified based on soil chemical composition (i.e. Carbohydrates, lignin, N-rich SOM and P-rich SOM) and the degree of SOM depolymerization. The enzyme functional groups for decomposition of each SOM pool and N/P mineralization are identified by the relative composition of gene copy numbers. The responses of microbial activities and SOM decomposition to nutrient and water availability are simulated by optimizing the allocation of enzyme functional groups following the optimal foraging theory. The modeled dynamic enzyme allocation in response to P availability and the alternation of dry and wet seasons is evaluated by the metagenomics data measured from P addition and P-deficit soil samples in Panama sites. The implementation of dynamic enzyme allocation in response to nutrient and water availability in the CoMEND model enables us to capture the varying microbial activity and soil carbon dynamics in response to shifting nutrient constraints and the alternation of dry and wet seasons over time in tropical soils.