施肥及秸秆还田对砂姜黑土细菌群落的影响

利用Illumina平台Miseq高通量测序技术对小麦分蘖期砂姜黑土耕层土壤细菌进行高通量测序,结合相关生物信息学分析,探讨了不施化肥秸秆不还田(CK)、施化肥秸秆不还田(F)以及不施化肥秸秆还田(W)3种处理土壤细菌群落组成、多样性和结构的变化。结果显示,测序共获得14 873个OTUs,计173 323条读数,平均读长439 bp。砂姜黑土细菌优势门(相对丰度10%)为变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)和拟杆菌门(Bacteroidetes);优势纲(相对丰度10%)为α-变形菌纲(Alphaproteobacteria)、β-变形菌纲(Betaproteobacteria)、酸杆菌纲(Acidobacteria)、鞘脂杆菌纲(Sphingobacteriia)和γ-变形菌纲(Gammaproteobacteria);优势属(相对丰度1%)共47个,3个处理中均有分布的优势属21个,F处理的细菌优势属的种类最多,为39个。相对丰度最大的门、纲和属分别是变形菌门(38.7%~43.1%)、α-变形菌纲(14.5%~18.1%)和鞘氨醇单胞菌属(Sphingomonas)(4.6%~7.7%)。F处理细菌丰富度指数(Chao1指数和ACE指数)显著低于CK及W处理,W处理和CK处理土壤细菌丰富度指数无显著差异,与CK处理相比,F处理ACE指数降低22.8%。W处理土壤细菌Shannon多样性指数显著大于CK及F处理,W处理Shannon指数较CK处理提高4.1%,而F处理土壤细菌Shannon指数与CK处理无显著差异。F处理Simpson指数显著高于CK及W处理;F处理Simpson指数较CK处理提高38.1%,而W处理细菌Simpson指数最小,显著低于CK处理,较CK降低23.8%。分层聚类图显示在属的水平上,W处理和CK处理土壤细菌群落结构相似性较高,F处理与CK处理及W处理细菌群落结构差异较大。施化肥对土壤细菌优势类群组成、相对丰度及群落结构的影响大于秸秆还田,施化肥显著降低了土壤细菌丰富度,秸秆还田显著提高了土壤细菌的多样性。

Effects of fertilization and straw incorporation on bacterial communities in lime concretion black soil

Soil bacteria are important drivers of nearly all biogeochemical cycles in terrestrial ecosystems and participate in most nutrient transformation processes in the soil. Thus knowledge about the shift of microbial community structure and diversity following different agricultural management practices could improve our understanding of soil processes and help us to develop agricultural management strategies. Because most soil bacteria are nonculturable, and traditional molecular biology methods, such as DGGE, are partial, the researches on soil bacterial are limited. High-throughput sequencing technology provides an effective tool for microbial molecular biology research. In this study, the technology of high-throughput sequencing on Illumina MiSeq platform was adopted to investigate the effects of fertilization and straw residue incorporation on bacterial communities in lime concretion black soils. The 16S rRNA genes of topsoil bacteria in lime concretion black soil were sequenced by high-throughput sequencing on Illumina MiSeq platform and related biological analysis conducted to investigate the changes in soil bacterial composition, diversity and structure under 4 different fertilization practices at wheat tillering stage. Soil samples were collected in lime concretion black soils in Mengcheng, Anhui Province, China with 3 treatments (CK: no fertilization, no straw return; F: chemical fertilization without straw return; W: straw return without chemical fertilization). The results showed that 173 323 reads of 14 873 OTUs (operational taxonomic unit) were generated at 3% cutoff level under all treatments with an average length of 439 bp. Bacterial OTUs were classified into 19 different known phyla and 41 classes. Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes were the dominant phyla (with relative abundance > 10%) in lime concretion black soils. Then Alphaproteobacteria, Betaproteobacteria, Sphingobacteriia, Acidobacteria and Gammaproteobacteria were the dominant classes (with relative abundance > 10%). The total number of dominant genera (with relative abundance > 1%) in all 3 treatments was 47, of which 21 genera were found in all treatments, and the largest number (39) of dominant genera occurred under F treatment. The dominant phylum, class and genus with the highest relative abundances were Proteobacteria (38.7%?43.1%), Alphaproteobacteria (14.5%?18.1%) and Sphingomonas (4.6%?7.7%) in all 3 treatments. The richness indexes (Chao1 and ACE indexes) were significantly lower for F treatment than for CK and W treatments. ACE index decreased by 22.8% under F treatment compared with CK. The richness indexes (Chao1 and ACE indexes) of CK and W treatments were not significantly different from each other. The Shannon index of W treatment was significantly higher than that of CK and F treatments, it increased by 4.1% compared with CK. Then the Shannon indexes of CK and F treatments were also not significantly different from each other. The Simpson index of F treatment was significantly higher than that of CK and W treatments. The Simpson index of F treatment increased by 38.1% compared with CK treatment. The Simpson index of W treatment was lowest among 3 treatments, decreasing by 23.8% compared with CK treatment. Hierarchical cluster analysis showed that CK and W treatments were in the same cluster group, while F was in a different cluster group. All the above findings suggested that chemical fertilization had a stronger effect on the composition, relative abundance of the dominant bacterial group and bacterial structure in soils than incorporation of straw residue. While chemical fertilization decreased soil bacterial richness, it increased bacterial predominance. On the contrary, straw residue incorporation increased soil bacterial diversity, but decreased bacterial predominance.