论文题目：Microbial Physiological Adaptation to Biodegradable Microplastics Drives the Transformation and Reactivity of Dissolved Organic Matter in Soil
论文作者：Lin Liu, Long Hu, Yakov Kuzyakov, Matthias C. Rillig, Guilan Duan, Gehong Wei*, and Chun Chen*
论文摘要：The turnover of dissolved organic matter (DOM) in soil regulated by biodegradable microplastics (MPs) has garnered much attention due to its profound impact on the storage and stability of soil organic matter. However, the transformation and reactivity of plant-derived and microbially derived DOM by microorganisms adapted to biodegradable MPs, and the involved microbial physiological processes, remain nearly unknown. Here, we added virgin and aged polylactic acid (PLA) and polyhydroxyalkanoate (PHA) to agricultural soils and incubated for 56 days. Using stable isotope techniques, reactomics, and metagenomics, we found that the addition of both virgin and aged PLA induced hydroxylation, demethylation, and dehydrogenation of lignin-derived DOM, resulting in a 3-fold increase in their oxidation degree. PLA activated the enzymatic pathway for lignin-derived DOM decomposition and downregulated genes involved in bacterial anabolism, such as those related to protein, amino sugar, and peptidoglycan biosynthesis. In contrast, PHA increased the content of microbially derived DOM compounds such as proteins and amino sugars by 2.1-fold relative to the control with peptide chain elongation. PHA resulted in the degradation of lignin-derived DOM into pyruvate and acetyl-CoA, accelerated bacterial ATP synthesis, the de novo biosynthesis of proteins and peptidoglycan, and cell renewal and death, thereby increasing PHA- and soil organic matter-derived microbial necromass carbon. Our study provides new insights into the impact of biodegradable MPs on soil DOM transformation and underscores the importance of the microbial physiological processes involved.
可生物降解微塑料（MPs）调控的土壤中溶解性有机质（DOM）周转备受关注，其作用对土壤有机质的储存和稳定性具有深远的影响。然而，适应可生物降解MPs的微生物在植物源与微生物源DOM的转化与反应性方面的作用机制及其生理过程仍知之甚少。本研究将原始与老化的聚乳酸（PLA）和聚羟基脂肪酸酯（PHA）分别添加至农业土壤中培养56天，并结合稳定同位素技术、反应组学和宏基因组学进行分析。结果表明，原始和老化PLA的添加均诱导木质素源DOM发生羟基化、去甲基化和脱氢反应，使其氧化程度提高约3倍。PLA促进了木质素衍生DOM分解相关的酶促途径，同时抑制了细菌合成代谢过程中的基因表达，例如与蛋白质、氨基糖及肽聚糖生物合成相关的基因。相比之下，PHA的添加促进了肽链延长，使微生物源DOM组分（如蛋白质与氨基糖）的丰度较对照组提高约2.1倍。PHA驱动木质素衍生DOM向丙酮酸和乙酰辅酶A分解，加速了细菌ATP合成、蛋白质与肽聚糖的从头合成以及细胞更新与死亡，从而增加了PHA及土壤有机质衍生的微生物残体碳积累。本研究揭示了可生物降解MPs对土壤DOM转化的调控机制，并强调了相关微生物生理过程在DOM周转与有机碳稳定性中的关键作用。
论文链接：https://doi.org/10.1021/acs.est.5c09633