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Abstract：
Cryoconite is a granular structure present on the glaciers and ice sheets found in polar regions including the Himalayas. It is composed of organic and inorganic matter which absorb solar radiations and reduce ice surface albedo, therefore impacting the melting and retreat of glaciers. Though climate warming has a serious impact on Himalayan glaciers, the biodiversity of sub-glacier ecosystems is poorly understood. Moreover, cryoconite holes are unique habitats for psychrophile biodiversity hotspots in the NW Himalayas, but unfortunately, studies on the microbial diversity of such habitats remain elusive. Therefore, the current study was designed to explore the bacterial diversity of the Hamtah Glacier Himalaya using both culturable and non-culturable approaches. The culturable bacterial count ranged from 2.0 × 103 to 8.8 × 105 colony-forming units (CFUs)/g at the different locations of the glacier. A total of 88 bacterial isolates were isolated using the culturable approach. Based on the 16S ribosomal RNA gene (16S rRNA), the identified species belong to seven genera, namely, Cryobacterium, Duganella, Janthinobacterium, Pseudomonas, Peribacillus, Psychrobacter, and Sphingomonas. In the non-culturable approach, high-throughput sequencing of 16S rRNA genes (using MiSeq) showed unique bacterial community profiles and represented 440 genera belonging to 20 phyla, namely, Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Chloroflexi, Acidobacteria, Planctomycetes, Cyanobacteria, Verrucomicrobia, Spirochaetes, Elusimicrobia, Armatimonadetes, Gemmatimonadetes, Deinococcus-Thermus, Nitrospirae, Chlamydiae, Chlorobi, Deferribacteres, Fusobacteria, Lentisphaerae, and others. High relative abundances of Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes were observed in the samples. Phototrophic (Cyanobacteria and Chloroflexi) and nitrifier (Nitrospirae) in bacterial populations indicated sustenance of the micro-ecosystem in the oligotrophic glacier environment. The isolates varied in their phenotypic characteristics, enzyme activities, and antibiotic sensitivity. Furthermore, the fatty acid profiles of bacterial isolates indicate the predominance of branched fatty acids. Iso-, anteiso-, unsaturated and saturated fatty acids together constituted a major proportion of the total fatty acid composition. High cold-adapted enzyme activities such as lipase and cellulase expressed by Cryobacterium arcticum (KY783365) and protease and cellulase activities by Pseudomonas sp. strains (KY783373, KY783377-79, KY783382) provide evidence of the possible applications of these organisms. Additionally, antibiotic tests indicated that most isolates were sensitive to antibiotics. In conclusion, the present study contributed for the first time to bacterial diversity and biopotentials of cryoconites of Hamtah Glacier, Himalayas. Furthermore, the cold-adapted enzymes and polyunsaturated fatty acids (PUFAs) may provide an opportunity for biotechnology in the Himalayas. Inductively coupled plasma mass spectrometry (ICPMS) analyses showed the presence of several elements in cryoconites, providing a clue for the accelerating melting and retreating of the Hamtah glacier.
摘要：
Cryoconite是在包括喜马拉雅山在内的极地地区发现的冰川和冰盖上存在的颗粒状结构。它由吸收太阳辐射并减少冰面反照率的有机和无机物质组成，因此影响了冰川的融化和退缩。尽管气候变暖对喜马拉雅冰川有严重影响，人们对冰川下生态系统的生物多样性知之甚少。此外，冰冻岩洞是喜马拉雅山西北部嗜冷菌生物多样性热点的独特栖息地，但不幸的是,对这些栖息地的微生物多样性的研究仍然难以捉摸。因此,本研究旨在使用可培养和不可培养的方法探索喜马拉雅哈姆塔冰川的细菌多样性。在冰川的不同位置，可培养的细菌计数范围为2.0×103至8.8×105菌落形成单位（CFU）/g。使用可培养的方法分离出总共88个细菌分离物。基于16S核糖体RNA基因（16SrRNA），鉴定的物种属于七个属，即,低温细菌,Duganella,Janthinobacterium,假单胞菌,小芽孢杆菌,嗜冷杆菌,和鞘氨醇单胞菌。在非文化方法中，16SrRNA基因的高通量测序（使用MiSeq）显示出独特的细菌群落谱，代表了属于20个门的440个属，即,变形杆菌,放线菌,Firmicutes,拟杆菌,氯氟菌,酸杆菌,Planctomycetes,蓝细菌,Verrucomicrobia,螺旋藻,Elusimicrobia,Aramatimonadetes,双子座,异常球菌,Nitrosirae,衣原体,绿虫,去铁杆菌,镰刀菌,Lentisphaerae,和其他人。高相对丰度的变形杆菌，放线菌,Firmicutes,在样品中观察到拟杆菌。细菌种群中的光养（蓝细菌和氯氟菌）和硝化剂（Nitrospirae）表明了贫营养冰川环境中微生态系统的维持。分离株的表型特征各不相同，酶活性，和抗生素敏感性。此外，细菌分离物的脂肪酸谱表明支链脂肪酸占优势。Iso-,antiso-,不饱和脂肪酸和饱和脂肪酸一起构成总脂肪酸组成的主要部分。高冷适应性酶活性，例如由北极低温杆菌（KY783365）表达的脂肪酶和纤维素酶，以及由Pseudomonassp。菌株（KY783373，KY783377-79，KY783382）提供了这些生物可能应用的证据。此外,抗生素试验表明，大多数分离株对抗生素敏感。总之,本研究首次为哈姆塔冰川的冷冻菌的细菌多样性和生物潜能做出了贡献，喜马拉雅山.此外，冷适应酶和多不饱和脂肪酸（PUFA）可能为喜马拉雅山的生物技术提供机会。电感耦合等离子体质谱（ICPMS）分析显示，在低温中存在几种元素，为哈姆塔冰川加速融化和退缩提供了线索。
