Microbial transformation of arsenic species and their interaction with the carbon cycle play a major role in the mobility of this toxic metalloid in the environment. The influence of simple or complex organic substrates on arsenic bio-oxidation was studied using two bacterial strains: one - the arsenivorans strain of Thiomonas delicata - is able to use AsIII as sole energy source; the other, Herminiimonas arsenicoxydans, is not. Experiments were performed at two AsIII concentrations (75 and 2 mg/L). At 75 mg/L As, for both strains, expression of aioA gene decreased when yeast extract concentration was raised from 0.2 to 1 g/L. At 2 mg/L As, the presence of either yeast extract or simple (succinate or acetate) organic substrates in the medium during bacterial growth decreased the AsIII-oxidation rate by both strains. When added specifically during oxidation test, yeast extract but not simple organic substrates seems to have a negative effect on AsIII oxidation. Taken together, results confirm the negative influence of simple or complex organic substrates on the kinetics of microbial AsIII oxidation and suggest that this effect results from different mechanisms depending on the type of organic substrate. Further, for the first time, the influence of a complex organic substrate, yeast extract, on aioA gene expression has been evidenced.

中文翻译：

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简单或复杂的有机底物会抑制两个β-变形杆菌菌株中的亚砷酸盐氧化和aioA基因表达。

砷物种的微生物转化及其与碳循环的相互作用在该有毒准金属在环境中的迁移中起着重要作用。使用两种细菌菌株研究了简单或复杂的有机底物对砷生物氧化的影响：一种菌株-纤毛thiomonas delicata的砷厌食菌菌株-能够使用AsIII作为唯一能源。另一个不是。实验在两种AsIII浓度（75和2 mg / L）下进行。在75 mg / L As时，对于两种菌株，当酵母提取物浓度从0.2 g / L提高到1 g / L时，aioA基因的表达都会降低。在2 mg / L As下，细菌生长过程中培养基中酵母提取物或简单（琥珀酸盐或乙酸盐）有机底物的存在均降低了这两种菌株的AsIII氧化速率。当在氧化测试中专门添加时，酵母提取物而非简单的有机底物似乎对AsIII氧化有负面影响。两者合计，结果证实了简单或复杂的有机底物对微生物AsIII氧化动力学的负面影响，并表明这种影响是由不同的机制导致的，具体取决于有机底物的类型。此外，首次证明了复杂的有机底物酵母提取物对aioA基因表达的影响。结果证实了简单或复杂的有机底物对微生物AsIII氧化动力学的负面影响，并表明这种影响是由取决于有机底物类型的不同机制引起的。此外，首次证明了复杂的有机底物酵母提取物对aioA基因表达的影响。结果证实了简单或复杂的有机底物对微生物AsIII氧化动力学的负面影响，并表明这种影响是由取决于有机底物类型的不同机制引起的。此外，首次证明了复杂的有机底物酵母提取物对aioA基因表达的影响。