Reduction of Selenite by Bacterial Exudates
Reduction of Selenite by Bacterial Exudates
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DOI：
10.1016/j.gca.2022.10.014
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发表时间：
2022-10
影响因子：
5
通讯作者：
Leah Sullivan;M. Boyanov;J. T. Wright;Mark C. Warren;K. Kemner;J. Fein
中科院分区：
文献类型：
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作者：
Leah Sullivan;M. Boyanov;J. T. Wright;Mark C. Warren;K. Kemner;J. Fein
Se(IV) 的细菌还原是全球硒循环的重要组成部分，因此影响自然和污染环境中硒的归宿和运输。然而，尚不清楚细菌产生的渗出物是否能够独立于细菌细胞而减少硒。在这项研究中，我们测量了三种细菌的渗出液还原 Se(IV) 的速率和程度，并通过在用巯基特异性阻断分子处理渗出液后进行平行实验来确定渗出液巯基位点的重要性。我们还对三种细菌物种中的每一种进行了全细胞生物量实验，以确定仅渗出物减少相对于全生物量促进减少的重要性。在我们的实验条件下，枯草芽孢杆菌和恶臭假单胞菌的渗出物在大约 20-24 小时的滞后期后从溶液中去除 Se(IV)，但希瓦氏菌的渗出物在去除 Se(IV) 方面无效，除非细胞在 Se(IV) 存在的情况下生长。对于两者 B.枯草芽孢杆菌P.恶臭菌中，渗出物分子上的巯基位点的预处理阻断显着降低了 Se(IV) 去除的速率和程度，强烈表明渗出物分子上的巯基在 Se(IV) 还原机制中发挥着关键作用。 S 的行为。 oneidensisexudates 表明 Se(IV) 还原机制的上调可以响应细胞生长培养基中的 Se 含量而发生。我们的结果证明了一些细菌渗出物减少 Se(IV) 的能力，并表明在自然和工程环境中模拟硒循环时应考虑细菌渗出物的活性。
Bacterial reduction of Se(IV) is a significant component of the global selenium cycle, and hence affects the fate and transport of selenium in both natural and contaminated environments. However, it is unknown whether bacterially-produced exudates are capable of reducing selenium independent of bacterial cells. In this study, we measured the rate and extent of Se(IV) reduction by exudates from three bacterial species, and we determined the importance of exudate sulfhydryl sites by conducting parallel experiments after treatment of the exudates with a sulfhydryl-specific blocking molecule. We also conducted experiments with whole cell biomass for each of the three bacterial species to determine the importance of exudate-only reduction relative to whole biomass-promoted reduction. Under our experimental conditions, exudates from Bacillus subtilis and Pseudomonas putida remove Se(IV) from solution after an approximately 20–24 h lag period, but exudates from Shewanella oneidensis are ineffective at Se(IV) removal, except when the cells are grown in the presence of Se(IV). For bothB. subtilisandP. putida, pretreatment blocking of the sulfhydryl sites on the exudate molecules dramatically decreases the rate and extent of Se(IV) removal, strongly suggesting that sulfhydryl groups on the exudate molecules play a key role in the Se(IV) reduction mechanism. The behavior ofS. oneidensisexudates indicates that up-regulation of the Se(IV) reduction mechanism can occur in response to the Se content of the medium in which the cells grow. Our results demonstrate the capacity of some bacterial exudates to reduce Se(IV), and suggest that the activity of bacterial exudates should be accounted for when modeling selenium cycling in natural and engineered environments.