Gangwar Pooja, Alam Syed Imteyaz, Bansod Sunita, Singh Lokendra
Biotechnology Division, Defence Research and Development Establishment, Gwalior, India.
Can J Microbiol. 2009 May;55(5):564-77. doi: 10.1139/w09-011.
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.
喜马拉雅山脉的高海拔寒冷栖息地在细菌多样性方面鲜有研究。本文报道了通过依赖培养和不依赖培养的方法获得的多种细菌物种和系统发育型。还描述了细菌多样性随海拔和可用有机碳含量的系统发育分析及调节情况。嗜冷菌和耐冷菌在喜马拉雅栖息地中占主导地位，占培养菌株的60%。分离物产生一种或多种（多达五种）水解酶，脂肪酶是大多数菌株（62%）分泌的一种。从喜马拉雅西部土壤样本中获得的99个细菌菌株和74个克隆获得了部分16S rRNA基因序列。45%的培养细菌菌株属于变形菌门，其中39%属于γ-变形菌纲。厚壁菌门是第二丰富的门类，占总分离物的32%，其次是放线菌门（16%）和拟杆菌门（6%）。大多数菌株属于芽孢杆菌属（30%），其次是假单胞菌属（24%）和节杆菌属（12%）。在不依赖培养的研究中，属于变形菌门的系统发育型占主导（73%），其中大多数是β-变形菌纲（31%）。细菌多样性呈现出海拔梯度，随着海拔升高，属的数量逐渐减少。分离物与来自其他寒冷栖息地的细菌表现出密切的系统发育亲缘关系。
