混合菌群对偶氮染料的脱色降解研究进展

Research progress on microbial decolorization and degradation of azo dyes

偶氮染料废水的排放会对水生环境及人类健康造成严重威胁.目前生物法处理偶氮染料的应用与研究居于首位,而混合菌群因具有多种微生物间的协同作用成为当前研究的热点.综述混合菌群的构建及偶氮染料脱色降解的影响因素,并重点阐述偶氮染料降解机理及降解酶系的相关研究.研究发现,混合菌群较单一菌株具有较好的脱色降解性能;其中碳氮源、温度、pH值、染料结构与浓度、溶氧量等因素对降解染料具有重要影响.细菌复合菌群是通过分泌一系列的酶如偶氮还原酶等使其偶氮双键断裂,产生的芳香胺类物质进一步被氧化成CO2和H2O,揭示了偶氮还原酶降解偶氮染料时的两种可能机制,即有无依赖氧化还原介质的偶氮染料降解.真菌复合菌群是通过生化反应来催化偶氮染料降解,阐述了漆酶降解染料的机理,即底物自由基中间体的产生和氧气还原成水.细菌与真菌复合菌群则是通过降解酶系统与生化反应相结合来降解染料.最后提出单一菌株存在着降解不彻底、效果不理想等问题,指出未来应根据废水中偶氮染料的种类、结构特点构建具有特异性、高效性且降解多种偶氮染料的混合菌群,并开展其生物降解的分子机制研究,进而为微生物降解偶氮染料的研发提供参考与理论支撑.(图2表3参96)

The discharge of azo dye wastewater poses a serious threat to both the aquatic environment and human health.Thus,the application and investigation of biological treatments for azo dye wastewater is very important and the microbial consortium has become a hot topic for present studies owing to the synergy among different microorganisms.In this study,the construction of a microbial consortium and their influencing factors on the decolorization and degradation of azo dyes were reviewed,with emphasis on the degradation mechanism of azo dyes and the relative degrading enzyme systems.Results indicated that the microbial consortium had better decolorization and degradation performance than single microbial strains and factors including carbon and nitrogen sources,temperature,pH,dye structure and concentration,and dissolved oxygen had a great influence on the degradation of azo dyes by microbial consortiums.The microbial consortium constructed by bacteria broke the double azo bonds by secreting a series of enzymes such as azo reductase and the resulting aromatic amines were further oxidized into CO2 and H2O.From this,two possible mechanisms for the degradation of azo dyes were shown,i.e.,dependent and independent on the redox mediator in the degradation of azo dyes.The microbial consortium constructed from fungi catalyzed the degradation of azo dyes by secreting extracellular enzymes and biochemical reactions.The mechanism of laccase degradation of dyes was described,namely the production of substrate-free radical intermediates and the reduction of oxygen to water.The microbial consortium constructed from both bacteria and fungi was found to degrade azo dye by combining the bacterial enzyme system with the fungal-catalyzed biochemical reaction.The single strain was found to have some problems such as incomplete degradation and unsatisfactory effect.A microbial consortium with high specificity and efficiency as well as the ability to degrade various azo dyes should be constructed based on the type and structural characteristics of azo dyes in wastewater,and an investigation of the molecular mechanism of the biodegradation of azo dyes should be undertaken in the future.This study provides reference and theoretical support for the research and development of the microbial degradation of azo dye.