Arsenic detoxification within thermo-alkaline biofilms

Introduction: The fundamental principles driving community composition and dynamics of microbial mats in thermoalkaline springs are largely uncharacterized. High in not only temperature but also arsenic (As), the microbial populations of Yellowstone National Parks (YNP), USA thermal springs require unique detoxification mechanisms to survive and carry out basic biological functions. Methods: While many studies have focused on which microorganisms are present, few studies have integrated the use of metagenome sequencing, imaging techniques, and mass spectrometry to gain insight into how structure and function of the mat dwelling organisms might be impacted by the high arsenical species in the ecosystem. Results: Here, we demonstrate via metagenome sequencing that community composition, including microbial genera Roseiflexus, Thermus, and Synechococcus, and as detoxification abilities change with mat depth and distance from the springs. Arsenical speciation confirmed the generation of bioarsenicals by mat-dwelling microorganisms. Microscopy revealed stratification of microorganisms in the mat, potentially reflecting their arsenic redox capabilities. Discussion: These data demonstrate how microbial mats are modular, stratified systems that shape and are shaped by environmental and geochemical gradients. Together, these findings characterize novel complexity and associations between geochemical cycles of metals and metabolic adaptations necessary for microorganisms to inhabit thermal springs. In conclusion, these findings demonstrate physiochemical heterogeneity of microbial mats in YNP.

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