The Yilgarn Craton constitutes a large area of Western Australia and consists of mostly 2.8 billion year old granite-gneiss metamorphic terrain. Hundreds of ephemeral lakes are scattered across the Yilgarn Craton, the salinity is a result of years of erosion, evapoconcentration and salt scatter from the ocean. Although not all the lakes in this area are acidic, the Yilgarn Craton contains acidic ground waters from the oxidation of abundant sulfide minerals, ferrolysis and the lack of natural geochemical buffers (carbonate minerals). Acidic hypersaline lakes have been described as harboring one of the most biologically challenging waters found on Earth; however, are relatively understudied. These lakes are rare ecological niches that harbor microorganisms with the potential for unique biotechnological applications. This study aimed to explore the microbial ecology of eight acidic saline lakes from the Yilgarn Craton with varying levels of salinity and pH below 4.
Lake sampling included water, soil (at 0-10cm and 20-30cm depth) and salt brine samples. Soil samples were taken from roughly 30 sites within a 25-25m area covering the shore of the lake to the water’s edge and homogenised to represent the average microbial community of the area. Water samples were collected from the centre of the lake by filtering 5L of water through both 0.1um and 0.2um filters.
The microbial ecology of these lakes varies considerably in their diversity and abundances of microbial communities. This study discusses the environmental drivers of microbial ecology and diversity in these extreme acidic saline lakes. The most dominate families identified in the lakes were the archaeal families Halobacteriaceae and Nitrosotaleaceae, bacterial families Salinisphaeraceae, Flavobacteriaceae and Nocardiaceae and eukaryotic families Chlamydomonadales and Hypotrichia. A large amount of ASVs in this study could not be assigned taxonomic rankings to family level, highlighting the amount of unknown microbial life in these extreme environments. Further genomic studies of these environments will give insight into the genetic capabilities of these unique microbial communities.