Lake Magic, located on the Yilgarn Craton in southern Western Australia, is a round lake with ~1km diameter and harbours one of the most unique environments on earth. It exhibits co-stressors of pH 1.6-4.5 and salinity of 32% TDS. The lake is known to have the highest concentration of dissolved aluminium, iron and silica in the world. Lake Magic undergoes stages of flooding, evapo-concentration and desiccation, depending on the local seasons. Thus, a large population of halophilic, halotolerant and acidophilic organisms interacting to drive key biogeochemical cycles are expected to reside in the lake, but even rudimentary understanding of the dynamics of microbial diversity during various lake stages is absent. Here, we used a temporal approach to understand prokaryotic diversity and metabolic interactions in lake water, sediment and salt mat through cultivation dependent and independent methods. The diversity dynamics were studied via high throughput 16S rRNA amplicon sequencing and flow cytometry. To further understand the survival strategies of microbes, their microbial interactions were studied in detail using culture dependent methods. We established a bottom up approach by using bacterial species isolated from Lake Magic in a well-controlled synthetic community. We studied the species metabolic interactions in all mono and pairwise cultures. The results indicated that the microbial diversity and composition are significantly affected by lake conditions. Furthermore, it was seen through the different time points that the sediment and salt mat communities evolved, becoming more specialized in buffering the increased acidity in the lake, as a strategy to survive.
The results from this study sheds light on the potential tactics to survive in this extreme environment. Studying these communities enables us to understand organisms living at the limits of life.