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采用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术及扩增产物序列分析方法比较研究了呼伦贝尔5种草地类型(线叶菊草原、贝加尔针茅草原、羊草草原、大针茅草原、克氏针茅草原)土壤固氮微生物nifH基因多样性及群落结构特征。结果表明,不同草地类型间土壤固氮微生物群落组成差异显著,羊草草原和大针茅草原相似性较高,相似度为67%,而其他3个草地类型间相似性较低,相似度均低于60%。羊草草原土壤nifH基因多样性最高,其次是克氏针茅草原、大针茅草原和贝加尔针茅草原,线叶菊草原最低。系统发育分析结果表明,呼伦贝尔草原土壤固氮微生物大部分属于变形菌门的α-变形菌纲,分别隶属于慢生根瘤菌属、中慢生根瘤菌属、红假单胞菌属、固氮螺菌属。5种草地类型中,克氏针茅草原土壤中联合固氮菌和自生固氮菌居多,而其他4个草地类型均以共生固氮菌为优势生态类型。
The five grassland types of Hulunbeir (Siluriformes prairie, Stipa baicalensis, Leymus chinensis steppe, Stipa grandis) were compared by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and sequence analysis of amplified products Grassland, Stipa krylovii) soil nifH microbial diversity and community structure characteristics. The results showed that there was significant difference in the composition of soil nitrogen fixing microbial community between different grassland types. The similarity between Leymus chinensis steppe and Stipa grandis steppe was high, with a similarity of 67%, while the other three grassland types had lower similarity and lower similarity At 60%. The nifH gene diversity in Leymus chinensis grassland soil was the highest, followed by Stipa krylovii, Stipa grandis and Stipa baicalensis grassland, the lowest was Verbenaenidae grassland. Phylogenetic analysis showed that most of the nitrogen fixation microorganisms in the soil of Hulun Buir steppe belonged to the Proteobacteria of the Proteobacteria, belonging to Bradyrhizobium, Bradyrhizobium, Rhodopseudomonas, Rhodosporidium, Genus. Among the five grassland types, the combination of Azotobacter vinelandum and Azotobacter was the most dominant species in Stipa krylovii grassland, while the other four grassland types all took the symbiotic azotobacter as dominant ecological type.