Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore, 641003, India.
World J Microbiol Biotechnol. 2012 Feb;28(2):605-13. doi: 10.1007/s11274-011-0853-9. Epub 2011 Jul 30.
This study is aimed at assessing culturable diazotrophic bacterial diversity in the rhizosphere of Prosopis juliflora and Parthenium hysterophorus, which grow profusely in nutritionally-poor soils and environmentally-stress conditions so as to identify some novel strains for bioinoculant technology. Diazotrophic isolates from Prosopis and Parthenium rhizosphere were characterized for nitrogenase activity by Acetylene Reduction Assay (ARA) and 16S rRNA gene sequencing. Further, the culture-independent quantitative PCR (qPCR) was performed to compare the abundance of diazotrophs in rhizosphere with bulk soils. The proportion of diazotrophs in total heterotrophs was higher in rhizosphere than bulk soils and 32 putative diazotrophs from rhizosphere of two plants were identified by nifH gene amplification. The ARA activity of the isolates ranged from 40 to 95 nmol ethylene h(-1) mg protein(-1). The 16S rRNA gene analysis identified the isolates to be members of alpha, beta and gamma Proteobacteria and firmicutes. The qPCR assay also confirmed that abundance of nif gene in rhizosphere of these two plants was 10-fold higher than bulk soil.
本研究旨在评估在营养贫瘠的土壤和环境胁迫条件下大量生长的刺槐和胜红蓟根际可培养固氮细菌的多样性，以便为生物接种剂技术鉴定一些新的菌株。通过乙炔还原测定（ARA）和 16S rRNA 基因测序对来自刺槐和胜红蓟根际的固氮菌进行氮酶活性特征描述。此外，还进行了无培养定量 PCR（qPCR），以比较根际和土壤中固氮菌的丰度。与土壤相比，根际中固氮菌在总异养菌中的比例更高，并且通过 nifH 基因扩增从两种植物的根际中鉴定出 32 个假定的固氮菌。分离株的 ARA 活性范围为 40 至 95 nmol 乙烯 h(-1) mg 蛋白(-1)。16S rRNA 基因分析将分离株鉴定为α、β和γ变形菌门和厚壁菌门的成员。qPCR 检测也证实，这两种植物根际中 nif 基因的丰度比土壤高出 10 倍。
