Isolation Of Vat Blue RSN Degrading Bacteria And Primary Study On Its Mechanisms

Anthraquinone dyes are the second most used textile dyes after azo dyes.The microbial degradation of dyes has been receiving attention at home and abroad due to its low cost,sustainable development,practicality and broad prospects.To date,little is known about the biodegradation process of anthraquinone dyes.In this paper,the Vat Blue RSN(VB RSN)was target object.A VB RSN decoloring microbial consortium was obtained from the sludge of dyeing wastewater by the conventional enrichment culture technique.High-throughput sequencing technology analysis of the community composition of the microbial consortium reveal that Serratia became the predominant genus in the consortium.Then we successfully isolated this strain from the consortium and identified it belongs to Serratia marcescens by the morphology and 16 S rRNA sequence analysis,and designated it as WY31.The relationship between the growth of strain WY31 and the decolorization of VB RSN was studied.It was found that glucose was the most stable and effective carbon source in the decolorization process of strain WY31.Temperature and glucose concentration were the significant factors via PB experiments.The response surface method showed that the glucose concentration was 0.324 g/L,temperature was 30.675 °C and the decolorization rate was the highest at 91.849%.For the convenience of experiment,the condition was corrected as follows: temperature 30 °C,glucose concentration 0.3 g/L,the actual decolorization rate measured after 72 h is 90.17%,which indicated that model selection has practical value.The VB RSN degrading pathway by strain WY31 was firstly speculated by UV-Vis spectroscopy,HPLC and HPLC-MS.It was found that the degradation of anthraquinone dye VB RSN is prone to redox reaction at the amino and carbonyl positions,followed by hydrolysis,hydrogenation and deamination,hydroxyl groups to form a small molecule compound benzoic acid,followed by ortho-cleavage to form muconic acid.Finally,the analysis of genomic sequencing data and its annotation of strain WY31 revealed that the gene SmDyP is related to the process of decolorization.The gene is 963 bp in length and encodes dye decolorizing peroxidase(DyP)-Type B.The amino acid similarity is less than 58% compared to the currently reported DyP-Type B.The heterologous expression of the target gene showed that SmDyP played a significant role in the decolorization of VB RSN,and the decolorization rate of recombinant strain was over 90%.