Prokaryotic Community Structure Driven by Salinity and Ionic Concentrations in Plateau Lakes of the Tibetan Plateau

Abstract

dThe prokaryotic community composition and diversity and the distribution patterns at various taxonomic levels across gradients of salinity and physiochemical properties in the surface waters of seven plateau lakes in the Qaidam Basin, Tibetan Plateau, were evaluated using Illumina MiSeq sequencing. These lakes included Lakes Keluke (salinity, <1 g/liter), Qing (salinity, 5.5 to 6.6 g/liter), Tuosu (salinity, 24 to 35 g/liter), Dasugan (salinity, 30 to 33 g/liter), Gahai (salinity, 92 to 96 g/liter), Xiaochaidan (salinity, 94 to 99 g/liter), and Gasikule (salinity, 317 to 344 g/liter). The communities were dominated by Bacteria in lakes with salinities of <100 g/liter and by Archaea in Lake Gasikule. The clades At12OctB3 and Salinibacter, previously reported only in hypersaline environments, were found in a hyposaline lake (salinity, 5.5 to 6.6 g/liter) at an abundance of ϳ1.0%, indicating their ecological plasticity. Salinity and the concentrations of the chemical ions whose concentrations covary with salinity (Mg 2؉ , K ؉ , Cl ؊ , Na ؉ , SO 4 2؊ , and Ca 2؉ ) were found to be the primary environmental factors that directly or indirectly determined the composition and diversity at the level of individual clades as well as entire prokaryotic communities. The distribution patterns of two phyla, five classes, five orders, five families, and three genera were well predicted by salinity. The variation of the prokaryotic community structure also significantly correlated with the dissolved oxygen concentration, pH, the total nitrogen concentration, and the PO 4 3؊ concentration. Such correlations varied depending on the taxonomic level, demonstrating the importance of comprehensive correlation analyses at various taxonomic levels in evaluating the effects of environmental variable factors on prokaryotic community structures. Our findings clarify the distribution patterns of the prokaryotic community composition in plateau lakes at the levels of individual clades as well as whole communities along gradients of salinity and ionic concentrations.

Geographical Isolation, Buried Depth, and Physicochemical Traits Drive the Variation of Species Diversity and Prokaryotic Community in Three Typical Hypersaline Environments

“…Obviously, the deeper stratums were formed earlier than the upper stratums. The microbial community varied from different stratums with different geological history and environmental parameters, which was similar to the pattern that the microbial community shifted along with the salinity [11,12].…”

“…Clone library technology has been widely adopted to investigate the microbial community of salt mine samples [10]. Additionally, high-throughput sequencing has been widely used in recent years to investigate the prokaryotic community of different hypersaline environments [12,17]. Out of the salt mines investigated, the Dinyuan salt mine was most diverse: the total count of unique OTUs uncovered from Dinyuan was greater than the number of OTUs from XY and YYJ put together (Figure 3).…”

“…The concentration of element Ca is also similar between XY and YYJ, and is much higher than the Ca concentration of Z24 (Table 3). We speculated that the type and concentration of ions may largely modulate the pattern of the microbial community along with geographical isolation of hypersaline environments [12].…”

“…Microbial diversity in salt lakes fluctuates drastically during different seasons [11]. Ion composition and salt concentration have been proposed to be the main factors driving the microbial community structure in different salt lakes of the Tibetan Plateau [12]. Seasonal dynamics of microbial communities have also been The salt lake sample (salt brine; fluid) was collected from Chaka Salt Lake (CK) (3059 m above sea level) in Qinghai Province, China (Table 1 and Figure 1).…”

Microbial community structure and diversity within hypersaline Keke Salt Lake environments

“…The Qaidamu Basin of the Qinghai-Tibetan Plateau is known for its abundance of salt lakes, which cover the largest area of any region in the world (2×10 6 km 2 ), occur at the highest altitude (average >4500 m) and consists of thousands of lakes (Liu et al 2014;Zhong et al 2016). Qaidamu lakes are characterized by low nutrient content, low temperature, low productivity, and high exposure to UV radiation (Guan et al 2013).…”