Bacterial diversity of soil samples from the western Himalayas, India

Abstract

High-altitude cold habitats of the Himalayas are little explored with respect to bacterial diversity. Diverse bacterial species and phylotypes obtained by culture-dependent and culture-independent approaches are reported here. Phylogenetic analysis and modulation of bacterial diversity with altitude and available organic carbon content are also described. Psychrophilic and psychrotolerant bacteria dominated the Himalayan habitats, accounting for 60% of the cultivated strains. Isolates produced one or more (up to five) hydrolytic enzymes, lipase being the one secreted by most strains (62%). Partial 16S rRNA gene sequences were obtained for 99 bacterial strains and 74 clones obtained from soil samples from the western Himalayas. Forty-five percent of cultured bacterial strains belonged to the Proteobacteria group with 39% belonging to gamma-Proteobacteria. Firmicutes was the second most abundant class with 32% of the total isolates followed by Actinobacteria (16%) and Bacteroidetes (6%). Most of the strains belonged to the genus Bacillus (30%) followed by Pseudomonas (24%) and Arthrobacter (12%). In culture-independent studies, phylotypes belonging to the Proteobacteria were dominant (73%) with the majority being beta-Proteobacteria (31%). The bacterial diversity exhibited an altitude gradient with a gradual decline in the number of genera with increase in altitude. The isolates exhibited close phylogenetic affinities to bacteria from other cold habitats.

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas

“…Nemergut et al (2007) who studied the development of microbial communities along a receding glacier in Peru reported not just an increase in the complexity of the microbial communities with soil age but also an overall increase in similarity between the communities in the young soil to that of a mature soil with age. Similarly, Gangwar et al (2009) could show an increase in both bacterial population size and diversity with increasing altitude in Western Himalayian mountain tops. A similar trend was reported for the Rocky Mountains (Bryant et al, 2008).…”

Seasonal and altitudinal changes of culturable bacterial and yeast diversity in Alpine forest soils

“…Similar results were found with non-culture based assessment of bacterial communities at the sites investigated in this study in spring: the highest bacterial richness and diversity was found at the site at the lowest altitude (Siles and Margesin 2016). Distinct microbial community structures correlating with altitude have been observed in subalpine and alpine environments (Lipson 2007), Himalayan slopes (Gangwar et al 2009) and in Indian (Ma et al 2004), Chinese (Xu et al 2015) and Peruan mountains (Fierer et al 2011) among others.…”

“…Inverse correlations between bacterial community abundance and altitude were also found in Chinese and Indian mountain slopes (Ma et al 2004). Culture-independent approaches revealed a dominance of Betaproteobacteria at higher altitudes in western Himalayas, India, while Gammaproteobacteria , Bacteroidetes and lower proportions of Gram-positive bacteria (mainly Firmicutes ) dominated the culturable community (Gangwar et al 2009). However, others concluded that microbial diversity was not significantly altered across a montane elevational gradient in eastern Peru, using a barcoded pyrosequencing procedure, in opposition to the drastic changes observed for plant and animal taxa (Fierer et al 2011).…”

Metabolic Characterization of cold active Pseudomonas, Arthrobacter, Bacillus, and Flavobacterium spp. from Western Himalayas

“…The strains were selected from the set of 173 cultured and uncultured bacteria obtained from various environmental samples from Western Himalayas on the basis of their novelties both at 16S rRNA gene sequence and phenotypic level [7].…”

“…The cultured bacterial strains belonged to Protobacteria (largely gamma-Proteobacteria), Firmicutes, Actinobacteria, and Bacteroidetes [7]. Most of the strains belonged to the genus Bacillus (30%), followed by Pseudomonas (24%), Arthrobacter (12%), and Flavobacterium (6%).…”