复垦土壤细菌群落结构及其与土壤肥力的关系

为了解两淮煤矿区复垦状况及其对土壤微生物的影响机制，合理人工干预，快速有效提高复垦土壤生产力，本研究以煤矸石充填复垦土壤为研究对象，通过野外调查与采样分析，采用Illumina MiSeq 高通量测序分析土壤细菌特定基因片段V4 区域，基于非度量多维尺度分析、冗余分析、方差分析、肥力指数、回归模型方法，对矸石充填土壤不同复垦方向的土壤细菌优势群落和生物多样性进行了探索，明晰土壤细菌群落及其与土壤肥力的响应作用。研究结果表明：细菌群落组成上，不同复垦方向对细菌优势群落分布并无显著性影响，变形菌门、酸杆菌门和放线菌门菌群为主要优势菌群。土壤微生物多样性层面上，表层土壤微生物有较高的丰富度和多样性，均匀度并无显著性差异。微生物多样性在不同复垦方向不存在显著性差异，Shannon_Wiener指数介于5.23～6.91之间，Chao1指数为867.1～5436，Pielou指数介于0.79～0.84之间，表中层同深层土壤的细菌群落结构具有差异性。TN、SOM、AP和AK是影响土壤细菌群落的主要肥力因子，土壤肥力质量指数与奇古菌门相对丰度呈显著正相关（P＜0.01），同链霉菌属呈显著负相关（P＜0.05），在一定程度上可将二者的相对丰度作为评价复垦土壤肥力状况的重要生物指标。研究成果可为两淮矿区矸石充填复垦土壤在微生物层面提高肥力质量提供理论支持。

Bacterial community structure of reclaimed soil and its relationship with soil fertility

Abstract: Reclaimed soil can be utilized to quickly and effectively produce under reasonable manual intervention. This study aims to clarify the influence of the reclamation on soil microorganisms in the Lianghuai coal mine area. The coal gangue filling reclaimed soil was also taken as the research object in the field investigation and sampling. Illumina MiSeq high-throughput sequencing was used to analyze the V4 region of specific gene fragments of soil bacteria. Biodiversity was then explored to clarify the soil bacterial community and the response to soil fertility using non-metric multi-dimensional scale analysis, redundancy analysis, variance analysis, fertility index, and regression. The results show that there was no significant effect of reclamation directions on the distribution of bacterial dominant communities from the composition, but there were different proportions of reclamation directions. Specifically, Proteobacteria (32.42%-42.97%), Acidobacteria (10.47%- 15.87%), Actinobacteria (8.90%-18.28%) were the main dominant bacteria groups. Among them, Proteobacteria occupied the most, accounting for more than 30%. Alpha diversity demonstrated that there was no significant difference in the abundance and diversity of bacterial soil samples in different reclamation directions. Some indexes also maintained stable, where the Shannon_Wiener index ranged from 5.23 to 6.91, while Chao1 index ranged from 867.1 to 5436, and the Pielou index of each sample fluctuated around 0.8. Beta diversity analysis showed that there was also no significant difference in the composition of bacterial communities in different reclamation directions. Furthermore, the composition of soil bacterial communities was negatively correlated with the soil depth. The composition of soil bacteria was attributed to different living conditions in the top, middle, and bottom soil layers, such as moisture, aeration, temperature, and nutrients. The pH value was consistent with the change of the diversity index, indicating only a slight influence on the dominant microbial flora and biodiversity. A one-way analysis of variance was carried out on the soil fertility indexes of reclamation directions. It was found that the content of fertility indexes in the surface soil was much higher than that in the bottom soil in general. The fertility quality was evaluated in the order of the cultivated land > grassland > forest, where the cultivated land performed the best reclamation direction. The redundancy analysis showed that the TN, SOM, AP, and AK were the main fertility factors to determine the composition of soil bacterial communities. But, some dominant bacterial communities presented no response to the fertility factors, due to the high complexity of the soil microbial community and the regional conditions. The regression model showed that the soil fertility index was positively correlated with the relative abundance of the Thaumarchaeota (P<0.01), and the Streptomyces was negatively correlated (P<0.05). Moreover, there was no strong correlation with the main dominant phylum, due to the complexity of the soil environment of the coal gangue reclaimed land. Consequently, the relative abundance of Thaumarchaeota and Streptomyces can be selected as important biological indicators to evaluate soil fertility, according to the linear regression and the functional effects of Thaumarchaeota and Streptomyces. The finding can also provide strong theoretical support to improve the fertility and quality of the reclaimed soil with the gangue at the microbial level in the Lianghuai mining area.