Distribution of bacterial 3-OH-FAs in Chinese saline lakes and its implication for paleoclimate reconstruction

Abstract

Microbial communities in saline lakes are sensitive to environmental changes and showed promise for paleoclimate reconstruction. However, how the Gram-negative bacterial communities and their related membrane lipids, 3-hydroxy fatty acid (3-OH-FA), adapt to salinity change is still unclear. Here, we report the potential impacts of salinity and pH on 3-OH-FA distributions, based on saline lake samples, including lacustrine sediments and surrounding soils, collected from the Balikun Lake of the Xinjiang Province and 12 shallow lakes of the Inner Mongolia Province, China. Our results revealed that 3-OH-FAs in saline lakes are mainly derived from in situ production. The 3-OH-FA distributions are sensitive to salinity and pH variations. Specifically, in brackish lakes (< 30 ‰), salinity and pH dominated the distribution of 3-OH-FAs. However, in hypersaline lakes, salinity predominated the 3-OH-FA distributions. Moreover, multiple linear regression has been used to explore the potential salinity proxies based on 3-OH-FAs. The result revealed the promising potential of using 3-OH-FAs for paleoenvironment reconstruction, which provides alternative tools for investigating the paleoclimate changes in saline environments.