Arsenite Removal by Heterotrophic Consortium Dominated by Paenibacillus profundus

ALEJANDRA LIMA; ALBERT SAAVEDRA; M URBIETA; EDUARDO CORTON; EDGARDO DONATI

Tucuman

Congreso; Congreso Argentino de Microbiología General (XII SAMIGE); 2017

Asociación civil de microbiologia

Arsenic (As) toxicity for living species depends on their chemical form; As(V) is a molecular analog tophosphate thus it can enter the cell using phosphate transporters and it might inhibit the production ofenergy by oxidative phosphorylation, meanwhile As(III) is generally considered more toxic because itbinds to sulfhydryl groups which interferes with protein structure and function and it is also moremobile in the environment. Thus, the oxidation of As(III) to As(V) would be an important step todecrease toxicity and mobility of As in the environment. Natural environments exposed to arsenic,even those with low content, have been the source of microorganisms able to tolerate and metabolizearsenic compounds. The Copahue geothermal area, an extreme environment of volcanic originlocated in Neuquen province (Argentina) with low As soluble concentration, has been the source of Astolerant species found in different enrichment cultures. Interestingly, Paenibacillus profundus was themost abundant microorganism identified in an heterotrophic consortium able to tolerate 20 mM ofAs(III). This culture also showed positive amplification for the aioA gene which encode for aperiplasmic enzyme implicated in one of the main arsenic detoxification mechanisms in heterotrophsdue to its ability to oxidize As(III) in to the less toxic As(V). The aim of this study was to evaluated thecapacity of As(III) removal by this heterotrophic consortium called Het(As+3 20 mM). The consortiumwas inoculated in an Erlenmeyer flask with LB medium and supplemented with 100 ppm of As(III).Non-inoculated Erlenmeyer flask was set as sterile control. Both, culture and control, were made intriplicate and incubated in agitation at 30ºC. Samples were collected at initial time (T0) and at theexponential phase of microbial growth (T1). As(III) concentration was measured by ElectrochemicalAnodic Stripping using a gold disc electrode with a mercury film. The culture inoculated with theconsortium Het(As+3 20 mM) decreased 41% the As(III) content, while in the sterile control thedecrease was only 14%. This work evidence the ability of this consortium to remove As(III) from themedium making it a functional alternative to bioremediation processes in As contaminated sites. Onthe other hand, this is the first report of Paenibacillus profundus capacity to remove the As(III).