title: Differential distribution and abundance of diazotrophic bacterial communities across different soil niches using a gene-targeted clone library approach.
abstract: Diazotrophs are key players of the globally important biogeochemical nitrogen cycle, having a significant role in maintaining ecosystem sustainability. Saline soils are pristine and unexplored habitats representing intriguing ecosystems expected to harbour potential diazotrophs capable of adapting in extreme conditions, and these implicated organisms are largely obscure. Differential occurrence of diazotrophs was studied by the nifH gene-targeted clone library approach. Four nifH gene clone libraries were constructed from different soil niches, that is saline soils (low and high salinity; EC 3.8 and 7.1 ds m(-1) ), and agricultural and rhizosphere soil. Additionally, the abundance of diazotrophic community members was assessed using quantitative PCR. Results showed environment-dependent metabolic versatility and the presence of nitrogen-fixing bacteria affiliated with a range of taxa, encompassing members of the Alphaproteobacteria, Betaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, Cyanobacteria and Firmicutes. The analyses unveiled the dominance of Alphaproteobacteria and Gammaproteobacteria (Pseudomonas, Halorhodospira, Ectothiorhodospira, Bradyrhizobium, Agrobacterium, Amorphomonas) as nitrogen fixers in coastal-saline soil ecosystems, and Alphaproteobacteria and Betaproteobacteria (Bradyrhizobium, Azohydromonas, Azospirillum, Ideonella) in agricultural/rhizosphere ecosystems. The results revealed a repertoire of novel nitrogen-fixing bacterial guilds particularly in saline soil ecosystems.
authors.affiliation: Discipline of Marine Biotechnology and Ecology, CSIR-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), Bhavnagar, Gujarat, India; Academy of Scientific and Innovative Research (AcSIR), CSIR, New Delhi, India.
authors.forename: Basit
authors.initials: B
authors.lastname: Yousuf
authors.forename: Raghawendra
authors.initials: R
authors.lastname: Kumar
authors.forename: Avinash
authors.initials: A
authors.lastname: Mishra
authors.forename: Bhavanath
authors.initials: B
authors.lastname: Jha
mesh_terms: D058448:Biota; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015723:Gene Library; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010088:Oxidoreductases / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology
chemical_list: D004269:DNA, Bacterial; D010088:Oxidoreductases; C029130:nitrogenase reductase
keywords: clone library; diazotrophs; microbial diversity; nifH; saline soil