High-efficient biodegradation of refractory dye by a new bacterial flora DDMY1 under different conditions

Abstract

Industrial wastewater with refractory dyes is still considered as one kind of serious pollution. Biological treatments have shown great potential for the biodegradation of dyes. A new natural bacterial flora DDMY1 with efficient decolorization performance of azo dye reactive black 5 (RB5) was obtained from activated sludge by concentration gradient domestication. Morphological analysis, growth test, decolorization assay of different parameters, kinetics study and high-throughput sequencing were performed in this study. Morphological analysis showed the features of flora DDMY1 and growth curves emerged the temperature range suitable for the growth of flora DDMY1. Results of decolorization assays indicated that xylose and yeast extract could enhance the decolorization effect and flora DDMY1 could decolorize RB5 not only in wide ranges of pH values (4.0–9.0) and initial dye concentration (100–1000 mg L−1), but also in the optimum temperature (40 °C) and NaCl concentration (1.5%, w/v). Kinetics study of RB5 decolorization at 30–40 °C conformed to the first-order kinetic reaction equation. High-throughput sequencing analysis revealed the community structure of flora DDMY1 and the dominant genus unclassified_o_Pseudomonadales, which had synergistic effect on decolorization with unclassified_f_Alcaligenaceae, Pseudomonas and other genera. Findings of this study revealed a sort of natural bacterial flora that could accommodate different wastewater conditions and remove high-concentration refractory dyes efficiently. These results also indicated the possibility of treating dyeing wastewater on a large scale with different conditions.