Accelerated azo dye biodegradation and detoxification by Pseudomonas aeruginosa DDMZ1-2 via fructose co-metabolism

Fructose was served as a promising co-substrate to facilitate the biodegradation and detoxification of refractory reactive black 5 (RB5) by a novel isolated strain DDMZ1-2. Analysis of 16S rRNA gene sequence confirmed its identity as Pseudomonas aeruginosa sp. Herein, the strain DDMZ1-2 was capable of decolorizing RB5 at a wide range of pH values (3.5-10), temperatures (25-40 degrees C) and salinity levels (0%-5%) under static incubation. For a fructose addition, the strain could efficiently decolorize RB5 even in case of 1500 mg/L dyestuff concentration and greatly tolerate high concentrations (i.e., up to 500 mg/L) of heavy metal ions (Cd2+, Co2+, Mn2+, Cu2+, Zn2+ and Cr6+). An increased secretion and activity of extracellular azoreductase was measured for sample FRU200 (fructose added, 200 mg/L RB5) after 24 h. Real-time quantitative PCR approach suggested that azoreductase gene azoR3 was remarkably up-regulated by fructose addition. LC-QTOF-MS revealed RB5 dyestuff in sample FRU200 produced more intermediates with low molecular weight and potential reaction pathways. Microbial toxicity and phytotoxicity proved to be extremely reduced in RB5 degradation metabolites of fructose co-metabolism by the strain. Besides, the strain DDMZ1-2 was versatile and effective in decolorizing structurally discrepant dyes but with varying efficacy. These results give insights into the fructose co-metabolism for enhancing the biodegradation and detoxification capabilities of a novel isolated P. aeruginosa strain with great potentials for refractory dyeing wastewater remediation. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Fructose as a promising co-substrate was found to enhance the biodegradation and detoxification of refractory dye RB5 by a novel isolated Pseudomonas aeruginosa strain DDMZ1-2, leading to increased secretion and activity of extracellular azoreductase, production of more low molecular weight intermediates, and reduction of microbial toxicity and phytotoxicity in degradation metabolites.