Reports of aerobic biogenic methane (CH 4 ) have generated new views about CH 4 sources in nature. We examine this phenomenon in the free‐flowing Yellowstone river wherein CH 4 concentrations were tracked as a function of environmental conditions, phototrophic microorganisms (using chlorophyll a , Chl a , as proxy), as well as targeted methylated amines known to be associated with this process. CH 4 was positively correlated w...

Summary In environments where arsenic and microbes coexist, microbes are the principal drivers of arsenic speciation, which directly affects bioavailability, toxicity and bioaccumulation. Speciation reactions influence arsenic behaviour in environmental systems, directly affecting human and agricultural exposures. Arsenite oxidation decreases arsenic toxicity and mobility in the environment, and therefore understanding its reg...

Summary Environmental arsenic poisoning affects roughly 200 million people worldwide. The toxicity and mobility of arsenic in the environment is significantly influenced by microbial redox reactions, with arsenite (As III ) being more toxic than arsenate (As V ). Microbial oxidation of As III to As V is known to be regulated by the AioXSR signal transduction system and viewed to function for detoxification or energy generation...

Summary Wide‐spread abundance in soil and water, coupled with high toxicity have put arsenic at the top of the list of environmental contaminants. Early studies demonstrated that both concentration and the valence state of inorganic arsenic (arsenite, As(III) vs. arsenate As(V)) can be modulated by microbes. Using genetics, transcriptomic and proteomic techniques, microbe‐arsenic detoxification, respiratory As(V) reduction and...

Summary Microbial arsenite ( AsIII ) oxidation forms a critical piece of the arsenic cycle in nature, though our understanding of how and why microorganisms oxidize AsIII remains rudimentary. Our model organism A grobacterium tumefaciens 5 A contains two distinct ars operons ( ars1 and ars2 ) that are similar in their coding region content. The ars1 operon is located nearby the aio operon that is essential for AsIII oxidation....

Summary Arsenic ranks first on the US Environmental Protection Agency S uperfund L ist of H azardous S ubstances. Its mobility and toxicity depend upon chemical speciation, which is significantly driven by microbial redox transformations. Genome sequence‐enabled surveys reveal that in many microorganisms genes essential to arsenite ( AsIII ) oxidation are located immediately adjacent to genes coding for functions associated wi...

Summary Arsenic (As) is the most common toxic element in the environment, ranking first on the Superfund List of Hazardous Substances. Microbial redox transformations are the principal drivers of As chemical speciation, which in turn dictates As mobility and toxicity. Consequently, in order to manage or remediate environmental As, land managers need to understand how and why microorganisms react to As. Studies have demonstrate...