具有广谱偶氮还原能力柠檬酸菌AzoR-2的分离鉴定和还原特性研究

从印染活性污泥中分离到1株高效广谱偶氮还原菌AzoR-2,并对该菌株进行了鉴定和偶氮还原特性分析.通过细胞形态和BIOLOG细菌自动鉴定系统的生理生化特性及16S rDNA与β-内酰胺酶基因相结合的分子生物学特性的分析,鉴定该菌株为柠檬酸菌属细菌,定名为Citrobacter sp.AzoR-2.通过对其偶氮还原特性的研究表明,菌株AzoR-2能够在厌氧条件下利用多种有机物和氢气为电子供体还原多种偶氮化合物,具有广谱偶氮还原特征.对电子供体和偶氮键的定量分析表明,还原过程中偶氮键接受的电子全部来自一级电子供体.氧气对其偶氮还原具有强烈的抑制作用.该菌株的偶氮还原系统定位在菌体的细胞膜上,推测该菌株的偶氮还原与菌体膜上的电子传递过程密切相关.菌株AzoR-2的厌氧偶氮还原在碱性pH值范围发生,其反应的最适pH值为7.5.菌株偶氮还原要求的温度范围较宽泛,在20～40℃范围内都显还原活性,最适作用温度为35℃.具有偶氮还原能力的柠檬酸菌在受偶氮染料污染的环境以及在印染废水的脱色中,可以发挥重要作用.

Isolation, Identification and Characterization of a Broad-Spectrum Azo-reducing Citrobacter Strain AzoR-2

A broad-spectrum azo-reducing bacterial strain, AzoR-2, was isolated from a active-sludge of textile-printing wastewater treatment plant and the strain was identified and characterized. This strain was identified as Citrobacter sp. according to its morphological, physiobiochemical characteristics and analysis of its 16S rDNA and beta-lactamase gene sequence. Studies showed that strain AzoR-2 was able to reduce various azo dyes with several organic substances and H2 as electron donor and the electrons for azoreduction came from primary electron donor. The azoreduction by strain AzoR-2 was inhibited strongly by O2. The enzyme system for azoreduction of strain AzoR-2 was located on cellular membrane, suggesting that the microbial azoreduction is linked to electron transport chain. Azoreduction by strain AzoR-2 was occurred in the range of alkaline pH at the temperature range 20 - 40 degrees C with optimum pH 7.5 and 35 degrees C. Azo-reducing Citrobacter bacterium may play important roles in bioremediation of the environment contaminated by azo dyes and in the decolorization of textile-printing wastewater.