arsC GENE EXPRESSION OF Nostoc minutum IN THE PRESENCE OF ARSENIC(V)

FERRARI, SG,; RAY AM, ; SALINAS AG,; VEGA AE ; SILVA HJ

San Luis

Congreso; XXX Reunión Anual de la Sociedad de Biología de Cuyo.; 2012

Sociedad de Biología de Cuyo

Arsenic (As) contamination is a global growing environmental problem mainly due to leaching from geological formations and anthropogenic activities. Microorganisms have evolved As defense mechanisms being the most common the presence of the As resistance operon (ars). The arsC gene encodes an arsenate reductase involved in arsenate detoxification. In the present study, the presence and expression of arsC gene in Nostoc minutum was studied.Batch cultures were produced in Watanabe medium added with 1000 mg/l As(V) and incubated at 30°C under continuous illumination for 16 days. Growth was evaluated by OD and dry weight determinations. The arsC gene, together with the sdhA gene, as housekeeping gene, were analyzed. For RNA extraction, 7 and 14 days biomass were treated with TRIzol reagent. N. minutum specific growth rate and final biomass values were higher in 1000 mg/ l As (V) supplemented cultures than the control (1,60 g/l and 0,98 g/l respectively). The arsC gene expression showed a 1.4 fold increase in relation to the control after 14 days in the presence of As(V). The low increase observed in arsC gene expression during the process of metal detoxification could be due to the minor toxicity of As(V) with respect to As(III). This is a preliminary work and future studies are needed in order to assess the role of arsC gene in As resistance.