Eco-enzymatic stoichiometry and microbial non-homeostatic regulation depend on relative resource availability during litter decomposition.

[Display omitted] • Strong microbial-substrate interactions exist in transformation interface soil layers. • Microbial metabolism was limited by C and P during litter decomposition. • Microbial non-homeostatic behavior corresponded to the transition stage. • The effect of microbial factors on enzyme stoichiometry was more stable. The relationships between soil eco-enzymatic stoichiometry and substrate stoichiometry could be used to explain nutrient cycling processes regulated by microbial biomass stoichiometry. But what are the relationships between the stoichiometry of resources, microorganisms, and enzymes? We do not have a clear understanding yet, particularly in the different stages of litter decomposition. By analyzing the response of extracellular enzymatic stoichiometry to the imbalance between microbial and substrate stoichiometry, we explore the microbial-mediated litter transformation and microbial adaptation mechanisms in the transformation interface soil (TIS) layer. The results showed that soil microbial metabolism was limited by C and P during decomposition, peaking in the transition (middle) stage and then gradually decreasing. According to the judgment of microbial homeostasis (effect of substrate stoichiometry on microbial biomass stoichiometry), the microbial communities shift from homeostatic in the early stage to non-homeostatic in the middle stage and then return to homeostasis in the later stage. During the litter decomposition, the non-homeostatic period corresponded to the transition stage. That means severe microbial metabolic limitation is a potential determinant of microbial homeostasis. Soil microorganisms adapt and alleviate microbial metabolic limitations by adjusting extracellular enzyme activity and microbial non-homeostatic behavior when the available resources fail to satisfy microbial requirements. [ABSTRACT FROM AUTHOR]