Microbiology Laboratory, Department of Botany (DST-FIST and UGC-DRS Funded), Institute of Science, Visva-Bharati (A Central University), Santiniketan, West Bengal, 731235, India.
Present address: Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Baylor College of Medicine, Houston, TX, USA.
Extremophiles. 2020 Nov;24(6):875-885. doi: 10.1007/s00792-020-01201-0. Epub 2020 Sep 21.
Inland athalassohaline solar salterns provide unique opportunity to study microbial successions along salinity gradients that resemble transition in natural hypersaline lakes. We analyzed for the first time 16S rRNA gene amplicon sequences of bacteria (V1-V2) and archaea (V4-V5) in saltern brines of India's largest inland hypersaline Sambhar Lake. Brines of the salterns (S1-S4) are alkaline (pH 9.5-10.5) with salinities of 130, 170, 280 and 350 gL respectively. 16S rRNA gene copy-number of archaea outnumbered that of bacteria in all salterns. Their diversity also increased along S1 through S4, while that of bacteria decreased. Brines of S3 and S4 were dominated by specialized extreme halophilic bacterial (Halanaerobiales, Rhodothermaceae) and archaeal (Halobacteriales, Haloferacales) members with recognized salt-in strategy for osmoadaptation. Microbial assemblages positively correlated to saltern pH, total salinity, and ionic composition. Archaea in S1 and S2 were unprecedentedly represented by poorly known as-yet uncultivated groups, Woesearchaeota (90.35-93.51%) and Nanohaloarchaeota that belong to the newly proposed nano-sized superphylum DPANN. In fact, these taxa were identified in archaeal datasets of other athalassohaline salterns after re-analysis using latest RDP database. Thus, microbial compositions in hypersaline lakes are complex and need revisit particularly for their archaeal diversity to understand their hitherto unknown ecological function in extreme environments.
内陆盐水太阳能盐田为研究微生物沿类似于自然高盐湖泊过渡的盐度梯度的演替提供了独特的机会。我们首次分析了印度最大内陆高盐水湖桑巴尔湖盐田卤水的细菌（V1-V2）和古菌（V4-V5）16S rRNA 基因扩增子序列。盐田卤水（S1-S4）呈碱性（pH9.5-10.5），盐度分别为 130、170、280 和 350gL。所有盐田中古菌的 16S rRNA 基因拷贝数均多于细菌。它们的多样性也沿着 S1 到 S4 增加，而细菌的多样性则减少。S3 和 S4 的卤水主要由专门的极端嗜盐细菌（Halanaerobiales，Rhodothermaceae）和古菌（Halobacteriales，Haloferacales）组成，它们具有公认的盐适应策略来适应渗透压。微生物群落与盐田 pH、总盐度和离子组成呈正相关。S1 和 S2 中的古菌以前所未有的方式由尚未培养的未知群组 Woesearchaeota（90.35-93.51%）和 Nanohaloarchaeota 代表，它们属于新提出的纳米级超门 DPANN。事实上，在使用最新的 RDP 数据库重新分析其他盐水太阳能盐田的古菌数据集后，这些分类群被鉴定为其他盐水太阳能盐田的古菌数据集。因此，高盐水体中的微生物组成复杂，需要重新研究，特别是它们的古菌多样性，以了解它们在极端环境中迄今为止未知的生态功能。
