The azo dye is the most widely used in the textile industries. This type of dye is considered recalcitrant due the presence of aromatic ring in the molecule. When it inserted in the environment, cause environmental damage, like the interference in the absorption and reflection of light in the aquatic environment, and can to be carcinogenic and mutagenic, molecule with both the full and after decolonization. Research with the degradation of dye used microorganisms, especially bacteria, it have result in excellent reduction of compound, and the environmental benefit overlaps the treatment and / or physical chemical. In this study, a facultative anaerobic bacterium was used to decolorize nine dyes of azo type. The bacteria in the Tropical Culture Collection was certified how Shewanella putrefaciens and reference it is CCT 1967. This was a fractional factorial planning in order to observe the effects of variables (temperature, pH, microorganisms, culture medium and agitation) for the decolourization of dyes. The better condition analysis was determined for temperature 25 °C and pH 8.5. The result, under these conditions, was the discoloration of seven dyes, and in a dye was the precipitation of compound and, in other, not decolorized. The analysis in condition aerobic was also performed, and the result was not satisfactory for any of the dyes in question.