Phosphate solubilization by microorganisms in pyroclastic material from Half Moon Island in Antarctica: perspectives for astrobiology

Microorganisms play a crucial role in the phosphorus cycle, as they mineralize and immobilize organic phosphorus and solubilize and precipitate the inorganic fraction of it. In various regions of the planet, the functional capacity of microorganisms in the solubilization process has been evaluated; however, in polar regions, the difficulty in accessing samples and handling microorganisms presents a limitation for understanding this cycle. This study aimed to evaluate the phosphate-solubilizing capacity of culturable microorganisms present in volcanic soils of Half Moon Island in Antarctica and their astrobiological implications for Mars. Physicochemical soil analysis, traditional culture techniques, selective media cultivation, and enzymatic activity analysis for soil phosphatase were conducted. Growth of various isolates was observed across different sampling points, with phosphate-solubilizing activity ranging from 14.29 to 92.31% of the isolates at each sampling point. These bacteria showed a direct relationship with soil calcium content. Phosphatase activity recorded low values, possibly affected by temperature and the low metabolic rate of in situ microorganisms. The findings suggest that microorganisms in Antarctic volcanic soils could contribute to astrobiological exploration on Mars.