Molecular Microbiology and Human Diseases Research Group, National Institute of Fundamental Studies, Hantana Road, Kandy, Sri Lanka.
Department of Plant and Molecular Biology, University of Kelaniya, Kelaniya, Sri Lanka.
Curr Microbiol. 2021 Sep;78(9):3439-3452. doi: 10.1007/s00284-021-02608-4. Epub 2021 Jul 13.
Hot springs harbour diverse and interesting groups of microorganisms adapted to extreme conditions. However, due to limitations in the culture-dependent approach, most of such thermophiles remain uncultured and unexplored. Hence, this study was conducted to gain a comprehensive understanding of the bacterial diversity of Mahapelessa hot spring, Sri Lanka using both culture-dependent and culture-independent approaches. The in situ temperature of the water sample was 44.5 °C and the pH was 8.14. 16S rRNA Sanger sequencing of DNA extracted from the 18 bacterial isolates revealed the presence of eight genera belonging to two phyla: Proteobacteria (84%) and Firmicutes (16%) and the most abundant genus being Klebsiella. A total of 23 bacterial phyla representing 80 classes, 43 orders, 123 families, 205 genera and 83 species were detected by 16S rRNA V3-V4 region by amplicon metagenome sequencing of DNA extracted from water samples, where the most abundant phylum was the Proteobacteria (57.39%), followed by Firmicutes (23.7%) and Chloroflexi (4.14%). The three phyla Actinobacteria, Planctomycetes and Bacteroidetes were also detected less than 3% in abundance while 4.48% of bacteria could not be fit into any known phylum. The most abundant genera were Burkholderia (14.87%), Desulfotomaculum (7.23%) and Stenotrophomonas (6.1%). Four strictly anaerobic bacteria, Anaerosolibacter carboniphilus (0.71%), Bellilinea caldifistulae (0.04%), Salimesophilobacter vulgaris (0.1%), Anaerobacterium chartisolvens (0.12%); two potential plant growth-promoting bacteria, Azospirillum halopraeferens (0.04%) and Bradyrhizobium liaoningense (0.16%) and one potential alkali tolerant and sulphate-reducing bacterium, Desulfovibrio alkalitolerans (0.45%) were recorded. Pigmentiphaga sp. was isolated from Mahapelessa hot spring and to the best of our knowledge, this is the first record of this genus from a hot spring. This study gives insight into the vast bacterial diversity present in the Mahapelessa hot spring from the culture-independent approach which could not be identified using standard culturing techniques.
温泉蕴藏着适应极端条件的多样化和有趣的微生物群体。然而，由于受限于依赖培养的方法，大多数嗜热菌仍然未被培养和探索。因此，本研究采用依赖培养和非依赖培养的方法，对斯里兰卡 Mahapelessa 温泉的细菌多样性进行了全面的了解。水样的原位温度为 44.5°C，pH 值为 8.14。从 18 个细菌分离株中提取的 DNA 的 16S rRNA Sanger 测序显示，存在属于两个门的 8 个属：变形菌门（84%）和厚壁菌门（16%），最丰富的属是克雷伯氏菌。从水样中提取的 DNA 经 16S rRNA V3-V4 区域扩增子宏基因组测序共检测到 23 个细菌门，代表 80 纲、43 目、123 科、205 属和 83 种，其中最丰富的门是变形菌门（57.39%），其次是厚壁菌门（23.7%）和绿弯菌门（4.14%）。放线菌门、浮霉菌门和拟杆菌门的丰度也低于 3%，而 4.48%的细菌无法归入任何已知的门。最丰富的属是伯克霍尔德氏菌（14.87%）、脱硫梭菌（7.23%）和寡养单胞菌（6.1%）。还记录了 4 种严格厌氧细菌，即嗜碳气溶胶菌（0.71%）、巴氏芽孢杆菌（0.04%）、普通嗜热菌（0.1%）和厌氧芽胞杆菌（0.12%）；2 种潜在的植物促生菌，即淡红哈茨木霉（0.04%）和辽宁中华根瘤菌（0.16%）；以及 1 种潜在的耐碱和硫酸盐还原菌，即脱硫弧菌（0.45%）。从 Mahapelessa 温泉中分离出了噬菌属，据我们所知，这是该属首次从温泉中分离出来。本研究从非依赖培养的方法中深入了解了 Mahapelessa 温泉中存在的广泛的细菌多样性，而这些多样性是无法通过标准培养技术来识别的。
