Se(VI) reduction and the precipitation of Se(0) by the facultative bacterium Enterobacter cloacae SLD1a-1 are regulated by FNR

Document Type

Article

Publication Date

3-1-2007

Abstract

The fate of selenium in the environment is controlled, in part, by microbial selenium oxyanion reduction and Se(0) precipitation. In this study, we identified a genetic regulator that controls selenate reductase activity in the Se-reducing bacterium Enterobacter cloacae SLD1a-1. Heterologous expression of the global anaerobic regulatory gene fnr (fumarate nitrate reduction regulator) from E. cloacae in the non-Se-reducing strain Escherichia coli S17-1 activated the ability to reduce Se(VI) and precipitate insoluble Se(0) particles. Se(VI) reduction by E. coli S17-1 containing the far gene occurred at rates similar to those for E. cloacae, with first-order reaction constants of k = 2.07 × 10-2 h-1 and k = 3.36 × 10-2 h -1, respectively, and produced elemental selenium particles with identical morphologies and short-range atomic orders. Mutation of the fnr gene in E. cloacae SLD1a-1 resulted in derivative strains that were deficient in selenate reductase activity and unable to precipitate elemental selenium. Complementation by the wild-type fnr sequence restored the ability of mutant strains to reduce Se(VI). Our findings suggest that Se(VI) reduction and the precipitation of Se(0) by facultative anaerobes are regulated by oxygen-sensing transcription factors and occur under suboxic conditions. Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Identifier

33947434064 (Scopus)

Publication Title

Applied and Environmental Microbiology

External Full Text Location

https://doi.org/10.1128/AEM.02542-06

ISSN

00992240

PubMed ID

17261520

First Page

1914

Last Page

1920

Issue

6

Volume

73

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