Exploration of nifH gene through soil metagenomes of the western Indian Himalayas

Abstract

This group has previously highlighted the prevalence of Csp genes from cold Himalayan environments. However, this study has explored the uncultured diazotrophs from metagenomes of western Indian Himalayas. The metagenomic nifH gene clone library was constructed from the Temperate, Subtropical and Tarai soils of Western Himalaya, India followed by polymerase chain reaction (PCR) amplification. After preliminary screening, selected clones were sequenced. In silico analysis of the clones was done, which documented 83.33 % similarities with unculturable sequence database and more than 70 % similarity with culturable bacterial database. Detailed sequence analysis of 24 nifH clones showed similarity to the corresponding genera of diazotrophs belonging to alpha-, beta-, gamma- and delta-proteobacteria. The prominent diazotrophs were Azotobacter spp., Agrobacterium tumefaciens, Methylococcus capsulatus, Geobacter bemidjiensis, Dechloromonas aromatica, Burkholderia xenovorans, Xanthobacter autotrophicus and Sideroxydanslithotrophicus, respectively. Alignment of these clones with culturable bacterial database suggests that most of the sequences belong to γ-proteobacterium group.