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Redox Reactions of Phenazine Antibiotics with Ferric (Hydr)oxides and Molecular Oxygen

Wang, Yun and Newman, Dianne K. (2008) Redox Reactions of Phenazine Antibiotics with Ferric (Hydr)oxides and Molecular Oxygen. Environmental Science and Technology, 42 (7). pp. 2380-2386. ISSN 0013-936X. PMCID PMC2778262.

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Phenazines are small redox-active molecules produced by a variety of bacteria. Beyond merely serving as antibiotics, recent studies suggest that phenazines play important physiological roles, including one in iron acquisition. Here we characterize the ability of four electrochemically reduced natural phenazines—pyocyanin (PYO), phenazine-1-carboxylate (PCA), phenazine-1-carboxamide, and 1-hydroxyphenazine (1-OHPHZ)—to reductively dissolve ferrihydrite and hematite in the pH range 5–8. Generally, the reaction rate is higher for a phenazine with a lower reduction potential, with the reaction between PYO and ferrihydrite at pH 5 being an exception; the rate decreases as the pH increases; the rate is higher for poorly crystalline ferrihydrite than for highly crystalline hematite. Ferric (hydr)oxide reduction by reduced phenazines can potentially be inhibited by oxygen, where O_2 competes with Fe(III) as the final oxidant. The reactivity of reduced phenazines with O_2 decreases in the order: PYO > 1-OHPHZ > PCA. Strikingly, reduced PYO, which is the least reactive phenazine with ferrihydrite and hematite at pH 7, is the most reactive phenazine with O_2. These results imply that different phenazines may perform different functions in environments with gradients of iron and O_2.

Item Type:Article
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URLURL TypeDescription CentralArticle
Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2008 American Chemical Society. Received September 12, 2007. Revised manuscript received January 2, 2008. Accepted January 4, 2008. We thank Thomas Hamann for his help with the electrode experiments, Ekaterina Pletneva and Jay Winkler for their help with the oxygen experiments, Michelle Scherer for the gift of the hematite samples, Alan Stone and Newman lab members for stimulating discussions, and four anonymous reviewers for insightful comments. This work was supported by grants to D. K. N. from the Packard Foundation and the Howard Hughes Medical Institute.
Funding AgencyGrant Number
David and Lucile Packard FoundationUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Issue or Number:7
PubMed Central ID:PMC2778262
Record Number:CaltechAUTHORS:20130506-090233889
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Official Citation:Redox Reactions of Phenazine Antibiotics with Ferric (Hydr)oxides and Molecular Oxygen Yun Wang and Dianne K. Newman Environmental Science & Technology 2008 42 (7), 2380-2386
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38284
Deposited By: Tony Diaz
Deposited On:06 May 2013 23:41
Last Modified:03 Oct 2019 04:55

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