全世界的纺织业每年要用到大约7×105吨的合成染料,而其中5万吨都会被释放到环境中,这些人工合成染料不仅污染水质,而且破坏光线的穿透、影响气体的溶解。含氮物、蒽醌和靓蓝是染料中的主要发色体,用物理和化学方法对发色体进行破坏受到了经济可行性及方法上的限制,因而目前研究多集中于采用生物酶法。
意大利的研究者Fabrizio Briganti等分析了F.trogii菌分泌出的氧化还原酶对几种常用染料的脱色效果,以及联合使用纤维二糖还原酶(CDH)或者漆酶的氧化还原介体对最顽固的染料的脱色效果。
通过研究F.trogii菌的生长曲线及优化条件,得出在培养菌株8~9天,可以获得0.6U/ml 的CDH产量和5~6 U/ml的漆酶酶活。分别用粗酶液与纯化后的漆酶在pH=3.0和pH=7.0时,对几种常用染料进行酶解脱色处理。结果表明,pH=7.0时,对几乎所有染料的脱色效果都很好,尽管此时的漆酶酶活较之于在pH=3.0时有了较大的降低,分析原因可能是因为pH=7.0时待测染料的溶解度最高。接着,又用添加了羟基苯并三唑(HBT)介体的漆酶液对以粗酶液处理脱色效果不明显的染料进行了脱色处理实验。漆酶/HBT体系比单纯使用漆酶在氧化染料发色基团上更有效,因为HBT是比漆酶更强的氧化剂,因而可以使某些比较顽固的染料氧化脱色。
CDH因为可以间接地产生强氧化性的羟基基团,因而具有替换昂贵的化学介体物质(如HBT)的潜力。通过在漆酶中添加CDH和30mM的乳糖(乳糖是激发CDH产生氧化性羟基基团的必需物质),对Reactive Red 272染料的脱色效力增强了4.3倍,同时,对蒽醌类染料的脱色效色也有很大的提高。
因而,将漆酶粗酶液或漆酶与CDH的混合酶液直接用在需要昂贵的化学处理及合成介体的染料脱色处理场合,将是未来处理废染料的发展趋势。相关论文发表在爱思唯尔期刊《生物资源技术》(Bioresource Technology)上。(生物谷Bioon.com)
生物谷推荐原始出处:
Bioresource Technology,Volume 99, Issue 15, October 2008, Pages 7003-7010,Ilaria Ciullini,Fabrizio Briganti
Fungal laccase, cellobiose dehydrogenase, and chemical mediators: Combined actions for the decolorization of different classes of textile dyes
Ilaria Ciullinia, Silvia Tillia, Andrea Scozzafavaa and Fabrizio Briganti, a,
Abstract
Dyes belonging to the mono-, di-, tri- and poly-azo as well as anthraquinonic and mono-azo Cr-complexed classes, chosen among the most utilized in textile applications, were employed for a comparative enzymatic decolorization study using the extracellular crude culture extracts from the white rot fungus Funalia (Trametes) trogii grown on different culture media and activators able to trigger different levels of expression of oxidizing enzymes: laccase and cellobiose dehydrogenase. Laccase containing extracts were capable to decolorize some dyes from all the different classes analyzed, whereas the recalcitrant dyes were subjected to the combined action of laccase and the chemical mediator HBT, or laccase plus cellobiose dehydrogenase. Correlations among the decolorization degree of the various dyes and their electronic and structural diversities were rationalized and discussed. The utilization of cellobiose dehydrogenase in support to the activity of laccase for the decolorization of azo textile dyes resulted in substantial increases in decolorization for all the refractory dyes proving to be a valid alternative to more expensive and less environmentally friendly chemical treatments of textile dyes wastes.