Efficient degradation and decolorization of triphenylmethane dyes by Serratia sp. WKD under extreme environmental conditions and the mechanism

Microbial degradation of dyes is fundamental and essential for understanding their environmental fate. In this study, a new bacterial strain with efficient degrading capability of triphenylmethane (TPM) dyes named WKD was isolated and identified as the genus Serratia sp. by 16S rDNA analysis. The decolorization of TPM dyes by the strain especially under extreme environmental conditions were studied. The results showed that the strain could completely decolorize Malachite Green (MG) and Crystal Violet (CV) at pH values ranging from 3.0 to 10.0 and at temperatures ranging from 20 degrees C to 45 degrees C in a 12 h of incubation. The strain still showed an excellent decol-orizing capability even at low (5 degrees C) and high (60 degrees C) temperatures. Moreover, the enzymatic analysis indicated that MnP, NADH-DCIP reductase, MG reductase, and CV reductase might be involved in TPM dyes biodegra-dation. Besides, the biodegradation pathways were proposed based on UV-visible, FTIR, and LC-Q-TOF-MS analyses. Results indicated that degradation of MG by the strain was mainly regulated by N-demethylation and hydroxylation pathways, while degradation of CV was only by the N-demethylation pathway. Therefore, Serratia sp. strain WKD is expected to have a broad application prospect for the bioremediation of TPM dyes, especially in extreme environments.