不同电子供体对Desulfovibrio dechloracetivorans strain SF3

还原脱氯,脱硫细菌Desulfovibrio dechloracetivorans strain SF3可异化还原三价铁,六价铬和三价钴. 乙酸盐,乙醇,氢气,丙酮酸盐,乳酸盐和柠檬酸盐可作为还原可溶性三价铁的电子供体,而只有丙酮酸盐和氢气做电子供体时SF3才能还原不可溶的非晶态三价铁氧化物. 实验测定Fe(Ⅲ)-EDTA还原对乙酸盐氧化的比例为7.76±0.35,而且该过程中没有伴随细菌的生长. SF3可利用氢气,丙酮酸盐或乳酸盐作为电子供体还原六价铬和三价钴, 但这一过程不能利用乙酸盐作为电子供体. 据我们所知,这是首次发现一种SRB(硫酸盐还原菌)可利用乙酸盐还原可溶性三价铁,但无法利用其还原不可溶三价铁以及六价铬和三价钴,该发现说明SF3在金属还原过程中利用了较复杂的电子传递系统.

Influence of different electron donors on metal reduction by Desulfovibrio dechloracetivorans strain SF3

Chlororespiring, sulfate-reducing bacterium Desulfovibrio dechloracetivorans strain SF3 is capable of dissimilatively reducing Fe(Ⅲ), Cr(Ⅵ) and Co(Ⅲ). Acetate, ethanol, hydrogen, formate, pyruvate, lactate and citrate can be used as electron donors for soluble Fe(Ⅲ) reduction, whereas poorly crystalline Fe(Ⅲ)-oxide can be reduced only in the presence of pyruvate or H2. Our experimental results show that the ratio of Fe(Ⅲ)-EDTA reduced to acetate consumed is 7.76±0.35, and no growth companied the Fe(Ⅲ) reduction in the presence of acetate. Reduction of Cr(Ⅵ) and Co(Ⅲ) can be stimulated by hydrogen, pyruvate and lactate, but addition of acetate had no effect. To our knowledge, it is the first report that an SRB (sulfate-reducing bacteria) can utilize acetate as an electron donor for soluble Fe(Ⅲ) reduction but not for insoluble Fe(Ⅲ), and Cr(Ⅵ), Co(Ⅲ) reduction, which indicates that a complex electron transfer system is hired by strain SF3 for metal reduction.