嗜热菌群降解偶氮染料的特性及机制

Decolorization characteristics and mechanism of azo dyes by a thermophilic bacterial consortium

摘要:

【背景】印染废水的出水温度高，抑制了微生物对偶氮染料的降解，而关于嗜热菌在高温下降解偶氮染料的报道较少。【目的】富集能在高温下降解偶氮染料的嗜热微生物菌群，并研究其降解潜力和基因组特征。【方法】通过富集的方法获得嗜热微生物菌群，利用分光光度法测定其降解特性；采用全波长扫描、傅里叶变换红外吸收光谱(Fourier transform infrared spectroscopy, FTIR)和气相质谱(gas chromatography-mass spectrometer, GC-MS)分析其降解机理；采用植物毒性的方法比较偶氮染料降解前后的毒性；采用高通量测序技术分析其功能基因和群落结构。【结果】该菌群(SD1)可以在65 ℃降解偶氮染料，Caldibacillus、unclassified_f__Bacillaceae、Geobacillus等为优势属，在降解过程中起关键作用；菌群SD1能在较宽泛的pH (5.0-9.0)、温度(50-75 ℃)、染料浓度(100-500 mg/L)和盐度(1%-5%)降解酸性大红GR；偶氮还原酶和NADH-DCIP是主要的降解酶，GC-MS和FTIR结果表明菌群SD1通过偶氮键断裂降解酸性大红GR；植物毒性的结果表明，经菌群SD1脱色后酸性大红GR的毒性降低；与降解有关的功能基因有依赖NADH的黄素单核苷酸(flavin mononucleotide, FMN)偶氮还原酶基因和依赖FMN的还原酶基因。【结论】嗜热菌群SD1在处理高温印染废水中具有很大的应用潜力。

Abstract:

[Background] The high temperature of textile wastewater inhibits the degradation of azo dyes by microorganisms. Little is known about the degradation of azo dyes by thermophiles. [Objective] To enrich the thermophilic microbiota that can degrade azo dyes at high temperature and study their degradation potential and genomic characteristics. [Methods] We obtained a thermophilic bacterial consortium by the enrichment method and then studied its degradation characteristics by spectrophotometry. The degradation mechanism was analyzed by full-wavelength scanning, Fourier transform infrared spectroscopy (FTIR), and gas chromatography-mass spectrometry (GC-MS). The phytotoxicity of azo dyes before and after degradation was compared. The functional genes and structure were analyzed by high-throughput sequencing. [Results] A bacterial consortium (SD1) was enriched, which can degrade azo dye at 65 ℃. SD1 was mainly composed of Caldibacillus, unclassified_f__Bacillaceae, and Geobacillus. It could degrade acid red GR within pH 5.0–9.0, 50–75 ℃, dye concentration of 100–500 mg/L, and salinity of 1%–5%. Azo reductase and NADH-DCIP were the main degrading enzymes. The results of GC-MS and FTIR demonstrated that the azo bond was broken by SD1. The phytotoxicity of acid red GR decreased after degradation. The genes encoding NADH-dependent flavin mononucleotide (FMN) azo reductase and FMN-dependent reductase involved in the degradation were detected. [Conclusion] The thermophilic bacterial consortium SD1 has great potential to be applied in the treatment of high-temperature textile wastewater.