Microbial necromass accrual via anabolism is an important process contributing to the formation and accumulation of stable soil organic C (SOC). Both substrates and microbial community traits impact the rate and efficiency of microbial biomass production, yet their effects on necromass accumulation patterns and efficiency remain unclear. Here we selected six substrates to investigate substrate and community regulations on microbial necromass accumulation over a 476-day model soil incubation including three stages (microbial growth–starvation–reactivation) with varied supply of substrates or ¹³C-labeled glucose. Microbial respiration, the composition of main microbial groups, and necromass (amino sugars) production were examined along with ¹³C analysis to compare necromass accumulation from new OC and native SOC. We found that relative to fast-decomposing substrates, slow-decomposing substrate like lignin induced slow but steady necromass accrual in a long term. Exogenous glucose input stimulated necromass accumulation from new and native SOC during reactivation, especially in C (or energy)-limited model soils. Furthermore, the accumulation efficiency of amino sugars sourced from SOC and ¹³C-labeled glucose were positively related, suggesting microbial communities and soil properties affect necromass accrual efficiency. However, there was quite some scatter in the correlation, suggesting potential substrate effect and uncertainty in this relationship. Hence, the efficiency of soil “microbial C pump” (i.e., microbial transformation of exogenous substrates into microbial byproducts) fueled by exogenous substrate and native SOC needs to be further investigated. Collectively, these findings provide new information on the dynamics and efficiency of microbial necromass accumulation from different substrates in soils.

通过合成代谢产生的微生物坏死物质是促进稳定土壤有机碳 (SOC) 形成和积累的重要过程。底物和微生物群落特征都会影响微生物生物质生产的速率和效率，但它们对坏死物质积累模式和效率的影响仍不清楚。在这里，我们选择了六种底物来研究底物和群落在 476 天的模型土壤培养过程中对微生​​物坏死物质积累的调节，包括三个阶段（微生物生长-饥饿-再激活），底物或 13 C 标记的葡萄糖供应^不同。微生物呼吸、主要微生物群的组成和坏死物质（氨基糖）的产生与¹³C 分析以比较新 OC 和原生 SOC 的坏死物质积累。我们发现，相对于快速分解的底物，木质素等缓慢分解的底物会在长期内诱导缓慢但稳定的坏死物质累积。在再激活过程中，外源性葡萄糖输入刺激了新的和天然 SOC 的坏死物质积累，尤其是在 C（或能量）有限的模型土壤中。此外，来自 SOC 和^{13 的氨基糖的积累效率}C标记的葡萄糖呈正相关，表明微生物群落和土壤特性会影响坏死物质的累积效率。然而，相关性存在相当大的分散性，表明这种关系存在潜在的底物效应和不确定性。因此，需要进一步研究由外源底物和天然 SOC 驱动的土壤“微生物碳泵”（即微生物将外源底物转化为微生物副产物）的效率。总的来说，这些发现提供了关于土壤中不同基质的微生物坏死团积累的动力学和效率的新信息。