玉米根际和非根际土壤细菌微多样性与土壤有机碳矿化的关系

目的]运用高级别分类学分辨率揭示玉米根际和非根际土壤中细菌群落微多样性，并探讨微多样性与土壤有机碳矿化的关系，从更精细的分类学分辨率水平上为玉米根际土壤中微生物驱动的碳循环提供理论依据。方法]以西北农林科技大学曹新庄试验农场为依托，采取田间生长条件下玉米根际和非根际两种土壤类型。利用高通量测序技术，比较OTUs和ASVs两种分类学分辨率水平上玉米根际和非根际土壤中的细菌群落结构，揭示细菌群落的微多样性。同时通过培养试验检测根际和非根际土壤的有机碳矿化特性。结果]通过比较OTUs和ASVs两种分类学分辨率水平上的细菌群落，OTUs和ASVs两种方式显示出相似的细菌群落结构。在玉米根际和非根际土壤类型中，ASVs在更高分类学分辨率水平上描绘细菌群落组成，同时揭示了普遍存在于OTUs内的不同菌株或生态型。此外，两种不同生长策略(r-策略和K-策略)细菌物种的相对丰度差异是导致根际和非根际土壤细菌群落结构不同的主要因素。培养试验表明，根际土壤有机碳矿化量显著高于非根际土壤。3 a的连续采样分析结果表明，根系是田间成熟玉米根际和非根际土壤理化性质差异的主要因素而受时间(2019—2021年...

Relationship of Bacterial Microdiversity of Rhizosphere and Bulk Soil with Soil Organic Carbon Mineralization in Maize Fields

Objective] The bacterial community microdiversity in the maize rhizosphere and bulk soil was determined to study the relationship between microdiversity and soil organic carbon mineralization through the use of high-resolution taxonomy in order to provide a theoretical foundation for microbially driven carbon cycling in the maize rhizosphere. Methods] The rhizosphere and bulk soil samples were collected in maize fields on the experimental farm of Cao Xinzhuang, Northwest A&F University. High-throughput sequencing technology was used to detect the bacterial community structure in the rhizosphere and bulk soil. Thereafter, distinct taxonomic resolution levels (OTUs vs ASVs) were used to reveal the microdiversity of bacterial communities. Incubation experiments were conducted to examine organic carbon mineralization characteristics of the rhizosphere and bulk soil of maize. Results] The distinct taxonomic resolution levels revealed similar bacterial community structure in the rhizosphere and bulk soil. ASVs depicted bacterial community composition at a fine scale taxonomic resolution level, and revealed different strains or ecotypes prevalent within the same OTU. Furthermore, differences in the relative abundance of bacterial species from distinct growth strategies (r-and K-strategies) were the main factors contributing to the different bacterial community structures in the rhizosphere and bulk soil. Incubation experiments showed that organic carbon mineralization was significantly higher in the rhizosphere than in bulk soil. The results of three years of continuous sampling revealed that roots were the main factor causing differences between the rhizosphere and bulk soil physicochemical properties of mature maize in the field, and that time had little influence (from 2019 to 2021). Cumulative mineralization of soil organic carbon was associated with bacterial microdiversity between the rhizosphere and bulk soil. Conclusion] ASV-level exhibited significant differences in bacterial microdiversity between the rhizosphere and bulk soil in a maize field, and bacterial microdiversity was associated with cumulative mineralization of soil organic carbon.