Zhao Danqi, Zhang Wei, Cui Juntao
College of Resources and Environment, Jilin Agricultural University, Changchun, Jilin, China.
College of Modern Agriculture, Chang Chun Polytschnic, Changchun, Jilin, China.
PeerJ. 2024 Apr 29;12:e17269. doi: 10.7717/peerj.17269. eCollection 2024.
Previous research on whole-soil measurements has failed to explain the spatial distribution of soil carbon transformations, which is essential for a precise understanding of the microorganisms responsible for carbon transformations. The microorganisms involved in the transformation of soil carbon were investigated at the microscopic scale by combining 16S rDNA sequencing technology with particle-level soil classification.
In this experiment,16S rDNA sequencing analysis was used to evaluate the variations in the microbial community structure of different aggregates in no-tillage black soil. The prokaryotic microorganisms involved in carbon transformation were measured before and after the freezing and thawing of various aggregates in no-tillage black soil. Each sample was divided into six categories based on aggregate grain size: >5, 2-5, 1-2, 0.5-1, 0.25-0.5, <0.25 mm, and bulk soil.
The relative abundance of Actinobacteria phylum in <0.25 mm aggregates was significantly higher compared to that in other aggregates. The Chao1 index, Shannon index, and phylogenetic diversity (PD) whole tree index of <0.25 mm aggregates were significantly smaller than those of in bulk soil and >5 mm aggregates. Orthogonal partial least-squares discrimination analysis showed that the microbial community composition of black soil aggregates was significantly different between <1 and >1 mm. The redundancy analysis (RDA) showed that the organic carbon conversion rate of 0.25-0.5 mm agglomerates had a significantly greater effect on their bacterial community structure. Moreover, humic acid conversion rates on aggregates <0.5 mm had a greater impact on community structure. The linear discriminant analysis effect size (LEfSe) analysis and RDA analysis were combined. Bradyrhizobium, Actinoplane, Streptomyces, Dactylosporangium, Yonghaparkia, Fleivirga, and Xiangella in <0.25 mm aggregates were positively correlated with soil organic carbon conversion rates. Blastococcus and Pseudarthrobacter were positively correlated with soil organic carbon conversion rates in 0.25-0.5 mm aggregates. In aggregates smaller than 1 mm, the higher the abundance of functional bacteria that contributed to the soil's ability to fix carbon and nitrogen.
There were large differences in prokaryotic microbial community composition between <1 and >1 mm aggregates. The <1 mm aggregates play an important role in soil carbon transformation and carbon fixation. The 0.25-0.5 mm aggregates had the fastest organic carbon conversion rate and increased significantly more than the other aggregates. Some genus or species of Actinobacteria and Proteobacteria play a positive role in the carbon transformation of <1 mm aggregates. Such analyses may help to identify microbial partners that play an important role in carbon transformation at the micro scale of no-till black soils.
以往对全土测量的研究未能解释土壤碳转化的空间分布，而这对于精确了解负责碳转化的微生物至关重要。通过将16S rDNA测序技术与颗粒级土壤分类相结合，在微观尺度上研究了参与土壤碳转化的微生物。
在本实验中，采用16S rDNA测序分析来评估免耕黑土中不同团聚体微生物群落结构的变化。测量了免耕黑土中各种团聚体冻融前后参与碳转化的原核微生物。每个样品根据团聚体粒径分为六类：>5、2 - 5、1 - 2、0.5 - 1、0.25 - 0.5、<0.25 mm，以及原状土。
<0.25 mm团聚体中放线菌门的相对丰度显著高于其他团聚体。<0.25 mm团聚体的Chao1指数、香农指数和系统发育多样性（PD）全树指数显著小于原状土和>5 mm团聚体。正交偏最小二乘法判别分析表明，<1和>1 mm的黑土团聚体微生物群落组成存在显著差异。冗余分析（RDA）表明，0.25 - 0.5 mm团聚体的有机碳转化率对其细菌群落结构的影响显著更大。此外，<0.5 mm团聚体上的腐殖酸转化率对群落结构的影响更大。将线性判别分析效应大小（LEfSe）分析和RDA分析相结合。<0.25 mm团聚体中的慢生根瘤菌属、放线飞机属、链霉菌属、指孢囊菌属、永哈帕克氏菌属、弗氏菌属和香氏菌属与土壤有机碳转化率呈正相关。芽孢球菌属和假节杆菌属与0.25 - 0.5 mm团聚体中的土壤有机碳转化率呈正相关。在小于1 mm的团聚体中，有助于土壤固碳和固氮能力的功能细菌丰度越高。
<1和>1 mm团聚体之间的原核微生物群落组成存在很大差异。<1 mm团聚体在土壤碳转化和固碳中起重要作用。0.25 - 0.5 mm团聚体的有机碳转化率最快，且比其他团聚体增加显著更多。放线菌门和变形菌门的一些属或种在<1 mm团聚体的碳转化中起积极作用。此类分析可能有助于识别在免耕黑土微观尺度上对碳转化起重要作用的微生物伙伴。
