1株具硫酸盐还原功能的柠檬酸杆菌的分离及其生理特性研究

Isolation and Characterization of a Sulfate Reducing Citrobacter sp.Strain SR3

从处理高浓度硫酸盐废水的厌氧上升流污泥床反应器（UASB）污泥中分离、纯化出1株具有硫酸盐还原功能的菌株SR3.经形态、生理生化特征试验和16S rDNA序列分析,该菌株SR3归属于柠檬酸杆菌（Citrobacter sp.）.其特性为：在厌氧和微氧条件下均可还原硫酸盐,同时用硫酸盐还原功能特异性基因引物可扩增到异化亚硫酸盐还原酶基因（dsr基因）;在好氧条件下不能还原硫酸盐但菌体生长速率最高,在厌氧条件下菌株生长的最适温度为37℃,最适起始pH值为8.0,在Cr（Ⅵ）初始浓度为0.4-0.8 mmol范围内能同时还原SO4^2-和Cr（Ⅵ）.对Cr（Ⅵ）的耐受能力达1 mmol.这是首次报道在兼性厌氧的柠檬酸杆菌中发现硫酸盐还原功能并携带硫酸盐还原酶基因的菌株.

A sulfate reducing bacterium,designated strain ‘SR3＇,was isolated from sludge of a sulfate-reducing up-flow anaerobic sludge bed（UASB） reactor for treating high concentration sulfate wastewater.It was identified as Citrobacter sp.based upon the phenotypic-characteristics and physiological properties as well as the analysis of the sequence of 16S rDNA.The strain could reduce sulfate under anaerobic and micro-aerobic conditions.The dissimilatory sulphite reductase gene（dsr） was also amplified from this strain＇s genomic DNA using specific dsr gene primers.In aerobic conditions,the strain couldn＇t reduce sulfate,but exhibited a highest growth rate.In anaerobic conditions,the optimal growth conditions for this stain were temperature 37℃ and initial pH 8.0.Under this conditions,the strain could reduced both SO4^2- and Cr（Ⅵ） at initial Cr（Ⅵ） concentrations of 0.4-0.8 mmol synchronously.Its tolerance ability to Cr（Ⅵ） concentrations reaches 1.0 mmol.This is the first report about an facultative anaerobe with sulfate reducing function and dissimilatory sulphite reductase gene（dsr）.