Degradation and detoxification of azo dyes by a salt-tolerant yeast Cyberlindnera samutprakarnensis S4 under high-salt conditions

Abstract

A new yeast strain which was capable of degrading various azo dyes under high-salt conditions was identified in this study. The results showed that the yeast named S4 was identified as Cyberlindnera samutprakarnensis through 26S rDNA sequence analysis and could decolorize more than 97% of Acid Red B (ARB) within 18 h under the optimal conditions. The acute toxicity of ARB sharply decreased after degradation. NADH-DCIP reductase and lignin peroxidase were determined as the key reductase and oxidase of the yeast S4, respectively. Furthermore, it was proposed that ARB was degraded by strain S4 successively through reduction of azo bonds, hydroxylation, deamination, desulfonation and finally to the TCA cycle.

Keywords: Azo dye; Cyberlindnera samutprakarnensis; Degradation pathways; Enzyme analysis; Salt-tolerant.