Microbial phosphorus recycling in soil by intra- and extracellular mechanisms
Jie Chen, Han Xu, Jasmin Seven, Thomas Zilla, Michaela A. Dippold, Yakov Kuzyakov
Abstract
Abstract Rising global stoichiometric imbalance between increasing nitrogen (N) availability and depleting phosphorus (P) resources increases the importance of soil microbial P recycling. The contribution of extra- versus intracellular P (re-)cycling depending on ecosystem nutrient status is vastly unclear, making soil microorganisms a blind spot in our understanding of ecosystem responses to increasing P deficiency. We quantified P incorporation into microbial DNA and phospholipids by 33P labeling under contrasting conditions: low/high P soil × low/high carbon (C)NP application. By combining 33P and 14C labeling with tracing of microbial community biomarkers and functional genes, we disengaged the role of DNA and phospholipids in soil P cycling. Microorganisms in low P soil preferentially allocated P to phospholipids with an acceleration of phospholipids metabolism driven by C addition, which was strongly related to high abundances of microbial community members (e.g. some G-) with a fast phospholipids turnover. In high P soil, however, more P was allocated to DNA with a microbial functional shift towards DNA synthesis to support a replicative growth when sufficient C was supplied, which was coupled with a strong enrichment of fungal copiotrophs and microbial genes coding DNA primase. Consequently, adaptation to low P availability accelerated microbial intracellular P recycling through reutilization of the P stored in phospholipids. However, microorganisms under high P availability commonly adopted extracellular P recycling with release and reuse of DNA P by microbial death-growth dynamics. These results advance our understanding on microbial adaptation to P deficiency in soil by regulating component-specific P pathways and reflect the specific functions of phospholipids and DNA for P recycling.