P20: Decoloration of the azo dye Direct Yellow 12 with Nocardia corallina

Azo dyes are xenobiotic compounds characterized by the presence of one or more azo groups (-N=N-), considered one of the most important groups in synthetic dyes. They are very recalcitrant due to its high stability to light and to microbial attack, resulting in severe pollution of rivers and groundwater in areas where are located textile and dyestuff industries, consequently the treatment of this kind of wastewater is difficult, physicochemical methods are the most used some of these methods are expensive and produce toxic pollutants. Biological process have become increasingly important for the treatment of azo dyes, mainly those involving the use of microorganisms, in this work was studied the capability of Nocardia corallina to decolorate the azo dye Direct yellow 12 (DY12).

The biotransformation with the N. corallina  was carried out in liquid medium, in the presence of 500 ppm of DY12, an after 48 hours the discoloration was of about 92%. The biodecoloration was followed by spectroscopic analysis of UV / VIS (at 400 nm), as well as infrared spectroscopic analysis and Nuclear Magnetic Resonance. It was found that the products of the biotransformation are far from the structure of Direct Yellow 12 dye, so it can be said that there is a biotransformation by Nocardia corallina B-276, however for the amounts used in this exploratory study it was not possible to obtain sufficient material to assign a structure to the major products observed. Then we can assume that N. corallina  is able to transform the dye.