Al-Tohamy Rania, Kenawy El-Refaie, Sun Jianzhong, Ali Sameh Samir
Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China.
Polymer Research Group, Department of Chemistry, Faculty of Science, Tanta University, Tanta, Egypt.
Front Microbiol. 2020 Jun 11;11:1163. doi: 10.3389/fmicb.2020.01163. eCollection 2020.
The effective degradation of hazardous contaminants remains an intractable challenge in wastewater processing, especially for the high concentration of salty azo dye wastewater. However, some unique yeast symbionts identified from the termite gut system present an impressive function to deconstruct some aromatic compounds, which imply that they may be valued to work on the dye degradation for various textile effluents. In this investigation, a newly isolated and unique yeast strain, SSA-1575, was identified from the gut system of a wood-feeding termite (WFT), . Under the optimized ambient conditions, the yeast strain SSA-1575 showed a complete decolorization efficiency on Reactive Black 5 (RB5) within 24 h, where this azo dye solution had a concentration of a 50 mg/L RB5. NADH-dichlorophenol indophenol (NADH-DCIP) reductase and lignin peroxidase (LiP) were determined as the key reductase and oxidase of SSA-1575. Enhanced decolorization was recorded when the medium was supplemented with carbon and energy sources, including glucose, ammonium sulfate, and yeast extract. To understand a possible degradation pathway well, UV-Vis spectroscopy, FTIR and Mass Spectrometry analyses were employed to analyze the possible decolorization pathway by SSA-1575. Determination of relatively high NADH-DCIP reductase suggested that the asymmetric cleavage of RB5 azo bond was mainly catalyzed by NADH-DCIP reductase, and finally resulting in the formation of colorless aromatic amines devoid of any chromophores. The ecotoxicology assessment of RB5 after a decolorization processing by SSA-1575, was finally conducted to evaluate the safety of its metabolic intermediates from RB5. The results of Microtox assay indicate a capability of SSA-1575, in the detoxification of the toxic RB5 pollutant. This study revealed the effectiveness of halotolerant yeasts in the eco-friendly remediation of hazardous pollutants and dye wastewater processing for the textile industry.
在废水处理中，有效降解有害污染物仍然是一项棘手的挑战，尤其是对于高浓度的含盐偶氮染料废水而言。然而，从白蚁肠道系统中鉴定出的一些独特酵母共生体展现出了分解某些芳香族化合物的惊人功能，这意味着它们在处理各种纺织废水的染料降解方面可能具有重要价值。在本研究中，从食木白蚁（WFT）的肠道系统中分离出了一种新的独特酵母菌株SSA - 1575。在优化的环境条件下，酵母菌株SSA - 1575在24小时内对浓度为50 mg/L的活性黑5（RB5）偶氮染料溶液展现出了完全脱色效率。NADH - 二氯酚靛酚（NADH - DCIP）还原酶和木质素过氧化物酶（LiP）被确定为SSA - 1575的关键还原酶和氧化酶。当培养基中添加碳源和能源，包括葡萄糖、硫酸铵和酵母提取物时，脱色效果得到增强。为了深入了解可能的降解途径，采用紫外 - 可见光谱、傅里叶变换红外光谱和质谱分析来分析SSA - 1575可能的脱色途径。较高的NADH - DCIP还原酶活性表明，RB5偶氮键的不对称裂解主要由NADH - DCIP还原酶催化，最终导致形成不含任何发色团的无色芳香胺。最后对SSA - 1575脱色处理后的RB5进行了生态毒理学评估，以评估其RB5代谢中间体的安全性。Microtox检测结果表明SSA - 1575具有对有毒RB5污染物进行解毒的能力。本研究揭示了耐盐酵母在对有害污染物进行生态友好型修复以及处理纺织工业染料废水方面的有效性。
