Figure 2 | Scientific Reports

Figure 2

From: Bacterial periplasmic nitrate and trimethylamine-N-oxide respiration coupled to menaquinol-cytochrome c reductase (Qcr): Implications for electrogenic reduction of alternative electron acceptors

Figure 2

Phenotypic analysis of a qcrABC deletion mutant grown under microaerobic conditions. (A) shows the specific rate of formate dependent oxygen consumption measured by an oxygen electrode in cell suspensions of the strains indicated. About 68% of the electron flux to oxygen proceeds through the cytochrome c oxidase (CcoNOQP) and, as expected, this is similar in the qcrABC mutant, which is the source of electrons for CcoNOQP. The alternative oxidase (CioAB) accounts for the remaining electron flux. The data shown are means and standard deviation of triplicate determinations (*P < 0.05 by one way ANOVA. NS, not significant). (B) Growth curves of the strains indicated under microaerobic conditions. The qcrABC strain shows a larger reduction in growth rate and cell yield compared to the ccoNOQP mutant. The data shown are the means and standard deviations of triplicate growth curves; in most cases the error bars are too small to be seen. (C) Accumulation of ROS in microaerobically incubated cells suspensions of wild-type and qcrABC mutant strains. The fluorescence emission of 2′,7′ dihydrodichlorofluorescein diacetate (H2DCFDA) added to 10 μM final concentration is shown, normalized to total cell protein. Data are means and standard deviations of triplicate experiments. (**P < 0.01, ***P = 0.001 by multiple t-tests).

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