Molecular mechanism triggered by co-metabolic biodegradation of azo dyestuff by Klebsiella sp. KL-1: Based on enzymatic and proteomic responsiveness

Abstract

In this study, xylose was utilized as co-substrate to reinforce the elimination of azo dyestuffs (reactive black 5, RB5) by Klebsiella sp. KL-1, and the underlying co-metabolic mechanism was deciphered from the proteomic viewpoint. The biotic removal process of RB5 was well followed by the first-order kinetic model, and the kinetic characteristics supported the superiority of xylose as co-substrate for more efficient reduction of azo dyestuffs. Notable levels of extracellular pivotal enzymes (azoreductase, laccase, manganese/lignin peroxidase) took place with xylose addition, which caused enhanced enzyme activities but with differential responsiveness. Proteomics analysis revealed that functional proteins including NADH-quinone oxidoreductase, NADH dehydrogenase, pyruvate dehydrogenase, etc. with varied catalytic activities were induced to be differentially expressed and principally positioned in central metabolic processes on account of xylose co-metabolism. These pivotal proteins potently triggered the production of more reducing force by the cells of Klebsiella sp. KL-1, thereby augmenting the overall electron transfer from intracellular to extracellular to realize the decomposition of target RB5 dyestuff. Overall, this study will provide in-depth insights into the molecular mechanism of co-metabolic biodegradation of recalcitrant textile effluents by an indigenous isolated Klebsiella strain.