Microbial Responses to Simulated Salinization and Desalinization in the Sediments of the Qinghai–Tibetan Lakes

Abstract

Uncovering microbial response to salinization or desalinization is of great importance to understanding of the influence of global climate change on lacustrine microbial ecology. In this study, to simulate salinization and desalinization, sediments from Erhai Lake (salinity 0.3-0.8 g/L) and Chaka Lake (salinity 299.3-350.7 g/L) on the Qinghai-Tibetan Plateau were transplanted into different lakes with a range of salinity of 0.3-299.3 g/L, followed by in situ incubation for 50 days and subsequent geochemical and microbial analyses. Desalinization was faster than salinization in the transplanted sediments. The salinity of the transplanted sediment increased and decreased in the salinization and desalinization simulation experiments, respectively. The TOC contents of the transplanted sediments were lower than that of their undisturbed counterparts in the salinization experiments, whereas they had a strong negative linear relationship with salinity in the desalinization experiments. Microbial diversity decreased in response to salinization and desalinization, and microbial community dissimilarity significantly (P < 0.01) increased with salinity differences between the transplanted sediments and their undisturbed counterparts. Microbial groups belonging to Gammaproteobacteria and Actinobacteria became abundant in salinization whereas Bacteroidetes and Chloroflexi became dominant in desalinization. Among the predicted microbial functions, hydrogenotrophic methanogenesis, methanogenesis through CO 2 reduction with H 2 , nitrate/nitrogen respiration, and nitrification increased in salinization; in desalinization, enhancement was observed for respiration of sulfur compounds, sulfate respiration, sulfur respiration, thiosulfate respiration, hydrocarbon degradation, chemoheterotrophy, and fermentation, whereas depressing was found for aerobic ammonia oxidation, nitrate/nitrogen respiration, nitrification, nitrite respiration, manganese oxidation, aerobic chemoheterotrophy, and phototrophy. Such microbial variations could be explained by changes of transplantation, salinity, and covarying variables. In summary, salinization and desalinization had profound influence on the geochemistry, microbial community, and function in lakes.

Chemical and Hygroscopic Characterization of Surface Salts in the Qaidam Basin: Implications for Climate Impacts on Planet Earth and Mars

“…The Chaka (CK) Lake is located on the eastern edge of the Qaidam Basin, and the lake is characterized as magnesium sulfate type. , The annual average temperature is 3.5 °C, the lowest monthly temperature at −12.4 °C is in January, and the highest at 14.4 °C is in July. The annual average precipitation is 198 mm, and the annual average evaporation is 2074 mm. , During the dry season, little brines remain, and during the wet season (May to September), the lake area is ∼116 km 2 with an average depth of 10 cm.…”

Actinobacterial and fungal strain-enriched wheat straw as an effective strategy for alleviating the effect of salinity stress on soil chemical and biochemical properties

“…In saline soils, the addition of plant residues increases microbial activity and biomass temporarily; as a result, microbial activity and biomass return to values similar to those in the unamended soils [5]. Similarly, previous studies have reported that application of plant residues could mitigate the effects of salinity on soil microbial properties under laboratory conditions [13] and also could improve soil fertility [48]. In fact, the addition of plant residues is a widely used practice to enhance soil fertility [39].…”

“…This can be attributed to the production of specific compounds and metabolites as well as the improvement of the soil fertility to the less decrease of microbial biomass in bacterial and fungal treatments under stress condition [16]. It seems that increased soil microbial biomass and their activity in soil treated with wheat residues could be due to the availability of easily degradable materials that provided nutrients and a suitable substrate for microorganisms [10,13].…”

Freshwater salinisation: a research agenda for a saltier world

“…For the lowest trophic levels (e.g., bacteria, fungi), changes in their communities either in the species composition and/or their activity induced by FS can modulate ecosystem functions and drive processes related to GHG production. Denitrification [69,111], methane production [112], but also dissolved organic carbon, detrital processing, and decomposition [39,68] are key aspects linked to microbial activity that need further attention. Molecular methods used to assess microbial diversity, linking it with functionality, can help to analyse these processes [76].…”