Appl Environ Microbiol. 1997 Jul;63(7):2785-91. doi: 10.1128/aem.63.7.2785-2791.1997.
We investigated the anaerobic biodegradation of 3-chlorobenzoate (3CBz) by microorganisms from an aquifer where chloroaromatic compounds were previously found to resist decay in the presence of sulfate. After a lengthy lag period, 3CBz was degraded in the presence of sulfate and concurrently with sulfate reduction. Chlorine removal from 2,5- or 3,5-dichlorobenzoates and the transient appearance of benzoate from 3CBz confirmed that reductive dehalogenation was the initial fate process for these substrates. Sulfate did not influence 3CBz degradation rates in acclimated enrichment cultures but accelerated the development of 3CBz degradation activity in fresh transfers. Benzoate degradation was more rapid in the presence of sulfate regardless of the enrichment history. Nitrate, sulfite, and a headspace of air inhibited 3CBz dehalogenation, while thiosulfate had no effect. Mass balance determinations revealed that 71 to 107% of the theoretically expected amount of methane was produced from 3CBz and benzoate oxidation in the absence of sulfate. In parallel cultures containing 15 mM sulfate, methanogenesis was reduced to 48 to 71% of that theoretically expected, while sulfate reduction accounted for 12 to 50% of the reducing equivalents. In either the presence or absence of sulfate, steady-state dissolved hydrogen concentrations were similar to those reported for sulfate-reducing or methanogenic environments, respectively. Molybdate inhibited sulfate reduction and 3CBz dehalogenation to a similar extent but did not affect benzoate biodegradation. Sulfate-dependent 3CBz biodegradation was not observed. We conclude that reductive dehalogenation and sulfate reduction occur concurrently in these enrichments and that the sulfate-dependent stimulation in fresh transfers was likely due to the acceleration of benzoate oxidation.
我们研究了在先前发现含氯芳香族化合物在存在硫酸盐的情况下难以降解的含水层中微生物对 3-氯苯甲酸（3CBz）的厌氧生物降解。在漫长的潜伏期后，3CBz 在硫酸盐的存在下并与硫酸盐还原同时被降解。从 2,5-或 3,5-二氯苯甲酸中去除氯以及 3CBz 中短暂出现的苯甲酸证实了还原脱卤是这些底物的初始命运过程。硫酸盐并没有影响驯化富集培养物中 3CBz 的降解速率，但加速了新鲜转移中 3CBz 降解活性的发展。无论富集历史如何，硫酸盐的存在都使苯甲酸的降解更快。硝酸盐、亚硫酸盐和空气的顶空抑制 3CBz 脱卤，而硫代硫酸盐没有影响。质量平衡测定表明，在不存在硫酸盐的情况下，从 3CBz 和苯甲酸氧化中产生的甲烷量为理论预期量的 71%至 107%。在含有 15 mM 硫酸盐的平行培养物中，甲烷生成减少到理论预期值的 48%至 71%，而硫酸盐还原占还原当量的 12%至 50%。在存在或不存在硫酸盐的情况下，稳态溶解氢浓度分别与硫酸盐还原或产甲烷环境中报道的相似。钼酸盐对硫酸盐还原和 3CBz 脱卤的抑制程度相似，但不影响苯甲酸的生物降解。未观察到依赖硫酸盐的 3CBz 生物降解。我们得出结论，在这些富集物中，还原脱卤和硫酸盐还原同时发生，而在新鲜转移中依赖硫酸盐的刺激可能归因于苯甲酸氧化的加速。
