Department of Geosciences, Mississippi State University, Starkville, MS, 39762, USA.
Interdisciplinary Centre for Water Research, Indian Institute of Science, Bangalore, 560012, India.
Sci Rep. 2020 Nov 26;10(1):20686. doi: 10.1038/s41598-020-77622-w.
The solar salterns in Tuticorin, India, are man-made, saline to hypersaline systems hosting some uniquely adapted populations of microorganisms and eukaryotic algae that have not been fully characterized. Two visually different microbial mats (termed 'white' and 'green') developing on the reservoir ponds (53 PSU) were isolated from the salterns. Firstly, archaeal and bacterial diversity in different vertical layers of the mats were analyzed. Culture-independent 16S rRNA gene analysis revealed that both bacteria and archaea were rich in their diversity. The top layers had a higher representation of halophilic archaea Halobacteriaceae, phylum Chloroflexi, and classes Anaerolineae, Delta- and Gamma- Proteobacteria than the deeper sections, indicating that a salinity gradient exists within the mats. Limited presence of Cyanobacteria and detection of algae-associated bacteria, such as Phycisphaerae, Phaeodactylibacter and Oceanicaulis likely implied that eukaryotic algae and other phototrophs could be the primary producers within the mat ecosystem. Secondly, predictive metabolic pathway analysis using the 16S rRNA gene data revealed that in addition to the regulatory microbial functions, methane and nitrogen metabolisms were prevalent. Finally, stable carbon and nitrogen isotopic compositions determined from both mat samples showed that the δC and δN values increased slightly with depth, ranging from - 16.42 to - 14.73‰, and 11.17 to 13.55‰, respectively. The isotopic signature along the microbial mat profile followed a pattern that is distinctive to the community composition and net metabolic activities, and comparable to saline mats in other salterns. The results and discussions presented here by merging culture-independent studies, predictive metabolic analyses and isotopic characterization, provide a collective strategy to understand the compositional and functional characteristics of microbial mats in saline environments.
印度 Tuticorin 的太阳能盐场是人为的，从盐沼中分离出了一些独特适应的微生物和真核藻类种群，这些种群尚未得到充分的描述。从盐沼中分离出了两种在水库池塘（53 PSU）上发育的视觉上不同的微生物垫（分别称为“白色”和“绿色”）。首先，分析了垫中不同垂直层的古菌和细菌多样性。非培养 16S rRNA 基因分析显示，细菌和古菌的多样性都很丰富。顶部层比深层部分具有更高的嗜盐古菌 Halobacteriaceae、绿弯菌门和 Anaerolineae、Delta 和 Gamma-Proteobacteria 的代表，表明垫内存在盐度梯度。蓝藻的存在有限，检测到与藻类相关的细菌，如 Phycisphaerae、Phaeodactylibacter 和 Oceanicaulis，这可能意味着真核藻类和其他光能生物可能是垫生态系统中的主要生产者。其次，使用 16S rRNA 基因数据进行预测代谢途径分析表明，除了调节微生物功能外，甲烷和氮代谢也很普遍。最后，从两个垫样品中确定的稳定碳和氮同位素组成表明，δC 和 δN 值随深度略有增加，范围分别为-16.42 至-14.73‰和 11.17 至 13.55‰。微生物垫剖面沿同位素的特征与群落组成和净代谢活动相一致，与其他盐场的盐垫相似。通过将非培养研究、预测代谢分析和同位素特征相结合，本文提出的结果和讨论为了解盐环境中微生物垫的组成和功能特征提供了一种综合策略。
