Dataset Information

Direct and Indirect Reduction of Cr(VI) by Fermentative Fe(III)-Reducing Cellulomonas sp. Strain Cellu-2a.

ABSTRACT: Hexavalent chromium (Cr(VI)) is recognized to be carcinogenic and toxic and registered as a contaminant in many drinking water regulations. It occurs naturally and is also produced by industrial processes. The reduction of Cr(VI) to Cr(III) has been a central topic for chromium remediation since Cr(III) is less toxic and less mobile. In this study, fermentative Fe(III)-reducing bacterial strains (Cellu-2a, Cellu-5a, and Cellu-5b) were isolated from a groundwater sample and were phylogenetically related to species of Cellulomonas by 16S rRNA gene analysis. One selected strain, Cellu-2a showed its capacity of reduction of both soluble iron (ferric citrate) and solid iron (hydrous ferric oxide, HFO), as well as aqueous Cr(VI). The strain Cellu-2a was able to reduce 15 μM Cr(VI) directly with glucose or sucrose as a sole carbon source under the anaerobic condition and indirectly with one of the substrates and HFO in the same incubations. The heterogeneous reduction of Cr(VI) by the surface-associated reduced iron from HFO by Cellu-2a likely assisted the Cr(VI) reduction. Fermentative features such as large-scale cell growth may impose advantages on the application of bacterial Cr(VI) reduction over anaerobic respiratory reduction.

SUBMITTER: Khanal A

PROVIDER: S-EPMC9706010 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature

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Direct and Indirect Reduction of Cr(VI) by Fermentative Fe(III)-Reducing <i>Cellulomonas</i> sp. Strain Cellu-2a.

Khanal Anamika A Hur Hor-Gil HG Fredrickson James K JK Lee Ji-Hoon JH

Journal of microbiology and biotechnology 20211101 11

Hexavalent chromium (Cr(VI)) is recognized to be carcinogenic and toxic and registered as a contaminant in many drinking water regulations. It occurs naturally and is also produced by industrial processes. The reduction of Cr(VI) to Cr(III) has been a central topic for chromium remediation since Cr(III) is less toxic and less mobile. In this study, fermentative Fe(III)-reducing bacterial strains (Cellu-2a, Cellu-5a, and Cellu-5b) were isolated from a groundwater sample and were phylogenetically ...[more]

PMID: 34489371

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Project description:Microbial reduction is an effective way to deal with hexavalent chromium [Cr(VI)] contamination in the environment, which can significantly mitigate the biotoxicity and migration of this pollutant. The present study investigated the influence of environmental factors on aqueous Cr(VI) removal by a newly isolated facultative anaerobic bacterium, Exiguobacterium sp. PY14, and revealed the reduction mechanism. This strain with a minimum inhibitory concentration of 400 mg/L showed the strongest Cr(VI) removal capacity at pH 8.0 because of its basophilic nature, which was obviously depressed by increasing the Cr(VI) initial concentration under both aerobic and anaerobic conditions. In contrast, the removal rate constant for 50 mg/L of Cr(VI) under anaerobic conditions (1.82 × 10-2 h-1) was 3.3 times that under aerobic conditions. The co-existence of Fe(III) and Cu(II) significantly promoted the removal of Cr(VI), while Ag(I), Pb(II), Zn(II), and Cd(II) inhibited it. Electron-shuttling organics such as riboflavin, humic acid, and anthraquinone-2,6-disulfonate promoted the Cr(VI) removal to varying degrees, and the enhancement was more significant under anaerobic conditions. The removal of aqueous Cr(VI) by strain PY14 was demonstrated to be due to cytoplasmic rather than extracellular reduction by analyzing the contributions of different cell components, and the end products existed in the aqueous solution in the form of organo-Cr(III) complexes. Several possible genes involved in Cr(VI) metabolism, including chrR and chrA that encode well-known Chr family proteins responsible for chromate reduction and transport, respectively, were identified in the genome of PY14, which further clarified the Cr(VI) reduction pathway of this strain. The research progress in the influence of crucial environmental factors and biological reduction mechanisms will help promote the potential application of Exiguobacterium sp. PY14 with high adaptability to environmental stress in Cr(VI) removal in the actual environment.

Dataset Information

Direct and Indirect Reduction of Cr(VI) by Fermentative Fe(III)-Reducing Cellulomonas sp. Strain Cellu-2a.

Publications

Direct and Indirect Reduction of Cr(VI) by Fermentative Fe(III)-Reducing <i>Cellulomonas</i> sp. Strain Cellu-2a.

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