Sung Youlboong, Ritalahti Kirsti M, Sanford Robert A, Urbance John W, Flynn Shannon J, Tiedje James M, Löffler Frank E
School of Civil and Environmental Engineering. School of Biology, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0512, USA.
Appl Environ Microbiol. 2003 May;69(5):2964-74. doi: 10.1128/AEM.69.5.2964-2974.2003.
Two tetrachlorethene (PCE)-dechlorinating populations, designated strains BB1 and BRS1, were isolated from pristine river sediment and chloroethene-contaminated aquifer material, respectively. PCE-to-cis-1,2-dichloroethene-dechlorinating activity could be transferred in defined basal salts medium with acetate as the electron donor and PCE as the electron acceptor. Taxonomic analysis based on 16S rRNA gene sequencing placed both isolates within the Desulfuromonas cluster in the delta subdivision of the Proteobacteria. PCE was dechlorinated at rates of at least 139 nmol min(-1) mg of protein(-1) at pH values between 7.0 and 7.5 and temperatures between 25 and 30 degrees C. Dechlorination also occurred at 10 degrees C. The electron donors that supported dechlorination included acetate, lactate, pyruvate, succinate, malate, and fumarate but not hydrogen, formate, ethanol, propionate, or sulfide. Growth occurred with malate or fumarate alone, whereas oxidation of the other electron donors depended strictly on the presence of fumarate, malate, ferric iron, sulfur, PCE, or TCE as an electron acceptor. Nitrate, sulfate, sulfite, thiosulfate, and other chlorinated compounds were not used as electron acceptors. Sulfite had a strong inhibitory effect on growth and dechlorination. Alternate electron acceptors (e.g., fumarate or ferric iron) did not inhibit PCE dechlorination and were consumed concomitantly. The putative fumarate, PCE, and ferric iron reductases were induced by their respective substrates and were not constitutively present. Sulfide was required for growth. Both strains tolerated high concentrations of PCE, and dechlorination occurred in the presence of free-phase PCE (dense non-aqueous-phase liquids). Repeated growth with acetate and fumarate as substrates yielded a BB1 variant that had lost the ability to dechlorinate PCE. Due to the 16S rRNA gene sequence differences with the closest relatives and the unique phenotypic characteristics, we propose that the new isolates are members of a new species, Desulfuromonas michiganensis, within the Desulfuromonas cluster of the Geobacteraceae.
从原始河流沉积物和氯乙烯污染的含水层物质中分别分离出两个四氯乙烯（PCE）脱氯菌群，分别命名为菌株BB1和BRS1。在以乙酸盐为电子供体、PCE为电子受体的限定基础盐培养基中，PCE到顺式-1,2-二氯乙烯的脱氯活性可以转移。基于16S rRNA基因测序的分类分析将这两个分离株置于变形菌门δ亚纲的脱硫单胞菌属簇中。在pH值7.0至7.5、温度25至30℃的条件下，PCE的脱氯速率至少为139 nmol min⁻¹ mg蛋白质⁻¹。在10℃时也发生脱氯。支持脱氯的电子供体包括乙酸盐、乳酸盐、丙酮酸盐、琥珀酸盐、苹果酸盐和富马酸盐，但不包括氢气、甲酸盐、乙醇、丙酸盐或硫化物。单独使用苹果酸盐或富马酸盐时可生长，而其他电子供体的氧化严格依赖于富马酸盐、苹果酸盐、三价铁、硫、PCE或三氯乙烯作为电子受体的存在。硝酸盐、硫酸盐、亚硫酸盐、硫代硫酸盐和其他氯代化合物不被用作电子受体。亚硫酸盐对生长和脱氯有强烈的抑制作用。替代电子受体（例如富马酸盐或三价铁）不抑制PCE脱氯，并且会同时被消耗。假定的富马酸盐、PCE和三价铁还原酶由各自的底物诱导产生，并非组成性存在。生长需要硫化物。两种菌株都能耐受高浓度的PCE，并且在游离相PCE（致密非水相液体）存在的情况下发生脱氯。以乙酸盐和富马酸盐为底物反复传代培养产生了一个失去PCE脱氯能力的BB1变体。由于与最接近的亲缘种的16S rRNA基因序列差异以及独特的表型特征，我们提议新分离株是地杆菌科脱硫单胞菌属簇内一个新物种——密歇根脱硫单胞菌的成员。
