Metabolite Identification from Biodegradation of Congo Red by Pichia sp.

Abstract

Azo dyes are commonly used in textile and paper industries. However, its improper disposal often results in polluting water bodies. Azo dyes can cause adverse health effects because of its carcinogenic properties. Various methods to remove azo dyes from water have been proposed, including biological methods such as biosorption and biodegradation. Biosorption and biodegradation were done by using bacteria, yeast or mold. In general, yeasts have some advantages for azo dyes degradation due to its faster growth compared to mold and better resistance against unfavorable environment compared to bacteria. Previously, we observed that yeast Pichia sp. have the ability to degrade Congo red, an azo dye. However, information regarding biodegradation of azo dyes by Pichia sp. are still limited. Therefore, in this study, we showed degradation of Congo red by Pichia sp. crude enzyme extract obtained from separating Pichia cells from medium by centrifugation, followed by identification of its biodegradation products. Biodegradation product was separated from enzyme by ethyl acetate and then Gas Chromatography-Mass Spectroscopy (GC-MS) method was employed to identify biodegradation product. Chromatogram results of GC-MS showed that Congo red were degraded into various products such as biphenyl, naphthalene and smaller molecules with 94 m/z and 51 m/z. These results suggest involvement of azo reductase and laccase-like enzymes which cleaves azo bonds and oxidize the dye molecules to smaller molecules. This study implies the use of Pichia sp. as a bioremediation agent for the removal of azo dyes.
 Keywords: Biodegradation, Congo red, Pichia sp., metabolite identification, GC-MS