The core microbiome of the AMF hyphosphere: mineralization mechanisms of key soil mineral elements.

Arbuscular mycorrhizal fungi (AMF) lack the enzymatic capacity to directly mineralize many essential soil elements and therefore rely on their hyphosphere core microbiome, a microbial consortium increasingly recognized as the "second genome" of AMF. However, the definition, functional mechanisms, and ecological relevance of this core microbiome remain poorly resolved. This review addresses how hyphosphere core microorganisms regulate the mineralization of soil carbon, nitrogen, phosphorus, and sulfur. We first outline the conceptual development of the core microbiome and then, for the first time, propose a five-dimensional screening framework integrating abundance stability and universality, functional stability, dynamic responsiveness, ecological niche specificity, and community supportiveness to identify authentic core members. Using this framework, we synthesize evidence on the mechanisms by which the hyphosphere core microbiome mediates biomineralization, highlighting its role in converting organically bound nutrients into plant-available forms. By integrating the functions of hyphosphere core microorganisms across carbon, nitrogen, phosphorus, and sulfur cycles, this review provides a unified ecological perspective on how the AMF hyphosphere core microbiome drives soil nutrient turnover (Fig. 1). Overall, this framework advances understanding of hyphosphere ecology and offers practical implications for soil ecosystem restoration and sustainable agricultural management.