Applied Environmental and Geomicrobiology Laboratory, Department of Microbiology, Quaid-i-Azam University, Islamabad, Pakistan.
Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, MD, USA.
Int Microbiol. 2021 May;24(2):183-196. doi: 10.1007/s10123-020-00153-x. Epub 2021 Jan 6.
High-altitude cold habitats of the Karakoram are rarely explored for their bacterial community characterization and metabolite productions. In the present study, bacterial communities in ice, water, and sediments of Batura Glacier were investigated using culture-dependent and culture-independent methods. Twenty-seven cold-adapted bacterial strains (mostly psychrotrophic) were isolated using R2A, Tryptic Soy Agar (TSA), and Luria-Bertani (LB) media, at 4 °C and 15 °C. Most of the isolates exhibited growth at a wide range of temperature (4-35 °C), pH (5-12), and salinity (1-6%). Among the bacterial isolates, 52% were identified as Gram-positive and the remaining 48% represented as Gram-negative. The results of phylogenetic analysis indicated that all the culturable bacteria belonged to 3 major phylogenetic groups, i.e., Actinobacteria (48%), Bacteroidetes (26%), and Proteobacteria (22%), while Flavobacterium (26%), Arthrobacter (22%), and Pseudomonas (19%) were represented as the dominant genera. Similarly, Illumina amplicon sequencing of 16S rRNA genes after PCR amplification of DNA from the whole community revealed dominance of the same phylogenetic groups, Proteobacteria, Actinobacteria, and Bacteroidetes, while Arthrobacter, Mycoplana, Ochrobactrum, Kaistobacter, Janthinobacterium, and Flavobacterium were found as the dominant genera. Among the culturable isolates, 70% demonstrated activity for cellulases, 48% lipases, 41% proteases, 41% DNases, and only 7% for amylases. Most of the glacial isolates demonstrated antimicrobial activity against other microorganisms including the multiple-drug-resistant strains of Candida albicans, Klebsiella pneumoniae, Acinetobacter sp., and Bacillus sp. 67% of Gram-negative while 46% of Gram-positive glacial bacteria were resistant to trimethoprim/sulfamethoxazole. Resistance against methicillin and vancomycin among the Gram-positive isolates was 23% and 15%, respectively, while 11% of the Gram-negative isolates exhibited resistance against both colistin sulfate and nalidixic acid.
喀喇昆仑山脉高海拔寒冷生境的细菌群落特征和代谢产物生产很少得到探索。在本研究中，使用培养依赖和非培养方法研究了巴图拉冰川的冰、水和沉积物中的细菌群落。使用 R2A、胰蛋白酶大豆琼脂（TSA）和 LB 培养基在 4°C 和 15°C 下分离了 27 株耐冷细菌菌株（主要是嗜冷菌）。大多数分离株在较宽的温度（4-35°C）、pH 值（5-12）和盐度（1-6%）范围内生长。在细菌分离物中，有 52%被鉴定为革兰氏阳性，其余 48%代表革兰氏阴性。系统发育分析的结果表明，所有可培养的细菌都属于 3 个主要的系统发育群，即放线菌（48%）、拟杆菌门（26%）和变形菌门（22%），而黄杆菌属（26%）、节杆菌属（22%）和假单胞菌属（19%）为优势属。同样，对来自整个群落的 DNA 进行 PCR 扩增后，16S rRNA 基因的 Illumina 扩增子测序显示，同样的优势为变形菌门、放线菌门和拟杆菌门，而节杆菌属、微体菌属、食酸菌属、卡斯特杆菌属、简青霉属和黄杆菌属为优势属。在可培养的分离物中，有 70%表现出纤维素酶活性，48%表现出脂肪酶活性，41%表现出蛋白酶活性，41%表现出 DNase 活性，只有 7%表现出淀粉酶活性。大多数冰川分离物对其他微生物表现出抗菌活性，包括耐多种药物的白色念珠菌、肺炎克雷伯菌、不动杆菌和芽孢杆菌的菌株。革兰氏阴性菌中有 67%对甲氧苄啶/磺胺甲恶唑耐药，革兰氏阳性菌中有 46%对甲氧苄啶/磺胺甲恶唑耐药。革兰氏阳性分离物对甲氧西林和万古霉素的耐药率分别为 23%和 15%，而革兰氏阴性分离物中有 11%对硫酸粘菌素和萘啶酸均耐药。
