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Electrochemical Potential Influences Phenazine Production, Electron Transfer and Consequently Electric Current Generation by Pseudomonas aeruginosa.

ABSTRACT: Pseudomonas aeruginosa has gained interest as a redox mediator (phenazines) producer in bioelectrochemical systems. Several biotic and abiotic factors influence the production of phenazines in synergy with the central virulence factors production regulation. It is, however, not clear how the electrochemical environment may influence the production and usage of phenazines by P. aeruginosa. We here determined the influence of the electrochemical potential on phenazine production and phenazine electron transfer capacity at selected applied potentials from -0.4 to +0.4 V (vs. Ag/AgCl_sat) using P. aeruginosa strain PA14. Our study reveals a profound influence of the electrochemical potential on the amount of phenazine-1-carboxylate production, whereby applied potentials that were more positive than the formal potential of this dominating phenazine (E^{° '}_PCA = -0.24 V vs. Ag/AgCl_sat) stimulated more PCA production (94, 84, 128, and 140 ?g mL^-1 for -0.1, 0.1, 0.2, and 0.3 V, respectively) compared to more reduced potentials (38, 75, and 7 ?g mL^-1 for -0.4, -0.3, and -0.24 V, respectively). Interestingly, P. aeruginosa seems to produce an additional redox mediator (with E^{° '} ? 0.052 V) at applied potentials below 0 V, which is most likely adsorbed to the electrode or present on the cells forming the biofilm around electrodes. At fairly negative applied electrode potentials, both PCA and the unknown redox compound mediate cathodic current generation. This study provides important insights applicable in optimizing the BES conditions and cultures for effective production and utilization of P. aeruginosa phenazines. It further stimulates investigations into the physiological impacts of the electrochemical environment, which might be decisive in the application of phenazines for electron transfer with P. aeruginosa pure- or microbial mixed cultures.

SUBMITTER: Bosire EM

PROVIDER: S-EPMC5435749 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Electrochemical Potential Influences Phenazine Production, Electron Transfer and Consequently Electric Current Generation by Pseudomonas aeruginosa.

Bosire Erick M EM Rosenbaum Miriam A MA

Frontiers in microbiology 20170518

Pseudomonas aeruginosa has gained interest as a redox mediator (phenazines) producer in bioelectrochemical systems. Several biotic and abiotic factors influence the production of phenazines in synergy with the central virulence factors production regulation. It is, however, not clear how the electrochemical environment may influence the production and usage of phenazines by P. aeruginosa. We here determined the influence of the electrochemical potential on phenazine production and ...[more]

PMID: 28572797

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Project description:Extracellular electron transfer (EET), the reduction of compounds that shuttle electrons to distal oxidants, can support bacterial survival when preferred oxidants are not directly accessible. EET has been shown to contribute to virulence in some pathogenic organisms and is required for current generation in mediator-based fuel cells. In several species, components of the electron transport chain (ETC) have been implicated in electron shuttle reduction, raising the question of how shuttling-based metabolism is integrated with primary routes of metabolic electron flow. The clinically relevant bacterium Pseudomonas aeruginosa can utilize carbon sources (i.e., electron donors) covering a broad range of reducing potentials and possesses a branched ETC that can be modulated to optimize respiratory efficiency. It also produces electron shuttles called phenazines that facilitate intracellular redox balancing, increasing the complexity of its metabolic potential. In this study, we investigated the reciprocal influence of respiratory metabolism and phenazine-associated physiology in P. aeruginosa PA14. We found that phenazine production affects respiratory activity and terminal oxidase gene expression and that carbon source identity influences the mechanisms enabling phenazine reduction. Furthermore, we found that growth in biofilms, a condition for which phenazine metabolism is critical to normal development and redox balancing, affects the composition of the P. aeruginosa phenazine pool. Together, these findings can aid interpretation of P. aeruginosa behavior during host infection and provide inroads to understanding the cross talk between primary metabolism and shuttling-based physiology in the diverse bacteria that carry out EET.IMPORTANCE The clinically relevant pathogen Pseudomonas aeruginosa uses diverse organic compounds as electron donors and possesses multiple enzymes that transfer electrons from central metabolism to O2 These pathways support a balanced intracellular redox state and produce cellular energy. P. aeruginosa also reduces secondary metabolites called phenazines to promote redox homeostasis and virulence. In this study, we examined the reciprocal relationship between these primary and secondary routes of electron flow. We found that phenazines affect respiratory function and that the complement of phenazines produced is strongly affected by growth in assemblages called biofilms. These results provide a more nuanced understanding of P. aeruginosa redox metabolism and may inform strategies for treating persistent infections caused by this bacterium.

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Electrochemical Potential Influences Phenazine Production, Electron Transfer and Consequently Electric Current Generation by Pseudomonas aeruginosa.

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Electrochemical Potential Influences Phenazine Production, Electron Transfer and Consequently Electric Current Generation by <i>Pseudomonas aeruginosa</i>.

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