Arsenite removal by heterotrophic consortium dominated by Paenibacillus profundus

LIMA, A; SAAVEDRA, A; URBIETA, M. S.; CORTON, C; DONATI, E. R.

San Miguel de Tucumán

Congreso; XII Congreso Argentino de Microbiologia General ? SAMIGE 2017; 2017

Asociación Civil de Microbiología General

Arsenic (As) toxicity for living species depends on their chemical form; As(V) is a molecular analog to phosphate thus it can enter the cell using phosphate transporters and it might inhibit the production of energy 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 more mobile in the environment. Thus, the oxidation of As(III) to As(V) would be an important step to decrease 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 origin located in Neuquen province (Argentina) with low As soluble concentration, has been the source of As tolerant species found in different enrichment cultures. Interestingly, Paenibacillus profundus was the most abundant microorganism identified in an heterotrophic consortium able to tolerate 20 mM of As(III). This culture also showed positive amplification for the aioA gene which encode for a periplasmic enzyme implicated in one of the main arsenic detoxification mechanisms in heterotrophs due to its ability to oxidize As(III) in to the less toxic As(V). The aim of this study was to evaluated the capacity of As(III) removal by this heterotrophic consortium called Het(As+3 20 mM). The consortium was 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 in triplicate and incubated in agitation at 30ºC. Samples were collected at initial time (T0) and at the exponential phase of microbial growth (T1). As(III) concentration was measured by Electrochemical Anodic Stripping using a gold disc electrode with a mercury film. The culture inoculated with the consortium Het(As+3 20 mM) decreased 41% the As(III) content, while in the sterile control the decrease was only 14%. This work evidence the ability of this consortium to remove As(III) from the medium making it a functional alternative to bioremediation processes in As contaminated sites. On the other hand, this is the first report of Paenibacillus profundus capacity to remove the As(III).