Laboratorio de Microbiología Molecular y Biotecnología, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela.
World J Microbiol Biotechnol. 2014 Mar;30(3):931-41. doi: 10.1007/s11274-013-1511-1. Epub 2013 Oct 2.
Glacial-ice microorganisms are intensively studied world-wide for a number of reasons, including their psychrophilic lifestyle, their usefulness in biotechnology procedures and their relationship with the search of life outside our planet. However, because of the difficulties for accessing and working at altitudes of >5.000 m above sea level, tropical glaciers have received much less attention than their arctic and antarctic counterparts. In the present work we isolated and characterized a total of forty-five pure isolates originating from direct plating of melted ice collected at the base of a rapidly-retreating, small glacier located at around 4.900 m.a.s.l. in Mount Humboldt (Sierra Nevada National Park, Mérida State, Venezuela). Initial examination of melted ice showed the presence of abundant- (>10⁶ cells ml⁻¹), morphologically diverse- and active bacterial cells, many of which were very small ("dwarf cells"). The majority of the isolates were psychrophilic or psychrotolerant and many produced and excreted cold-active extracellular enzymes (proteases and amylases). The antibiotic tests showed an elevated percentage of isolates resistant to high doses (100 μg/ml) of different antibiotics including ampicillin, penicillin, nalidixic acid, streptomycin, chloramphenicol, kanamycin and tetracycline. Multiresistance was also observed, with 22.22 % of the strains simultaneously resistant up to five of the antibiotics tested. Metal resistance against Ni⁺⁺, Zn⁺⁺ and Cu⁺⁺ was also detected. In accordance with these results, plasmids of low and high molecular weight were detected in 47 % of the isolates. Twenty-two partial 16S rDNA sequences analyzed allowed grouping the isolates within five different phyla/classes: Alpha-, Beta- and Gamma-proteobacteria, Actinobacteria and Flavobacteria. This is the first report concerning South American Andean glacial ice microorganisms.
冰川微生物因其嗜冷生活方式、在生物技术过程中的有用性以及与我们星球外生命的探索关系而受到全球广泛研究。然而，由于难以进入和在海拔 5000 米以上的高度工作，热带冰川受到的关注远不及它们的北极和南极对应物。在本工作中，我们共分离和鉴定了 45 个纯培养物，这些培养物源自融化冰的直接平板培养，融化冰是从安第斯山脉 Humboldt 山（内华达国家公园，梅里达州，委内瑞拉）海拔约 4900 米的快速退缩的小冰川底部采集的。融化冰的初步检查显示存在丰富的（>10⁶ 细胞 ml⁻¹）、形态多样且活跃的细菌细胞，其中许多非常小（“矮细胞”）。大多数分离株为嗜冷或耐冷，许多分离株产生和分泌冷活性胞外酶（蛋白酶和淀粉酶）。抗生素测试显示，对不同抗生素（包括氨苄青霉素、青霉素、萘啶酸、链霉素、氯霉素、卡那霉素和四环素）的高剂量（100 μg/ml）具有抗性的分离株比例较高。还观察到多药耐药性，22.22%的菌株同时对测试的五种抗生素中的五种具有抗性。还检测到对 Ni⁺⁺、Zn⁺⁺和 Cu⁺⁺的金属抗性。根据这些结果，在 47%的分离株中检测到低分子量和高分子量的质粒。分析的 22 个部分 16S rDNA 序列允许将分离株分为五个不同的门/纲：α-、β-和γ-变形菌、放线菌和黄杆菌。这是关于南美安第斯冰川微生物的首次报道。
