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Growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough under continuous low oxygen concentration sparging: impact of the membrane-bound oxygen reductases.

Ramel F, Brasseur G, Pieulle L, Valette O, Hirschler-Réa A, Fardeau ML, Dolla A - PLoS ONE (2015)

Bottom Line: Effect of constant low oxygen concentration on growth and morphology of the wild-type, single (Δbd, Δcox) and double deletion (Δcoxbd) mutant strains of the genes encoding these oxygen reductases was studied.Time-lapse microscopy revealed that a large majority of the cells were then able to divide (over 97%) but the time to recover a complete division event was longer for single deletion mutant Δbd than for the three other strains.We propose that the pyruvate-ferredoxin oxidoreductase (PFOR) plays a central role in this phenomenon by reversibly switching from an oxidative-sensitive fully active state to an oxidative-insensitive inactive state.

View Article: PubMed Central - PubMed

Affiliation: Aix-Marseille Université, CNRS, LCB-UMR7283, Marseille, France.

ABSTRACT
Although obligate anaerobe, the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough (DvH) exhibits high aerotolerance that involves several enzymatic systems, including two membrane-bound oxygen reductases, a bd-quinol oxidase and a cc(b/o)o3 cytochrome oxidase. Effect of constant low oxygen concentration on growth and morphology of the wild-type, single (Δbd, Δcox) and double deletion (Δcoxbd) mutant strains of the genes encoding these oxygen reductases was studied. When both wild-type and deletion mutant strains were cultured in lactate/sulfate medium under constant 0.02% O2 sparging, they were able to grow but the final biomasses and the growth yield were lower than that obtained under anaerobic conditions. At the end of the growth, lactate was not completely consumed and when conditions were then switched to anaerobic, growth resumed. Time-lapse microscopy revealed that a large majority of the cells were then able to divide (over 97%) but the time to recover a complete division event was longer for single deletion mutant Δbd than for the three other strains. Determination of the molar growth yields on lactate suggested that a part of the energy gained from lactate oxidation was derived toward cells protection/repairing against oxidative conditions rather than biosynthesis, and that this part was higher in the single deletion mutant Δbd and, to a lesser extent, Δcox strains. Our data show that when DvH encounters oxidative conditions, it is able to stop growing and to rapidly resume growing when conditions are switched to anaerobic, suggesting that it enters active dormancy sate under oxidative conditions. We propose that the pyruvate-ferredoxin oxidoreductase (PFOR) plays a central role in this phenomenon by reversibly switching from an oxidative-sensitive fully active state to an oxidative-insensitive inactive state. The oxygen reductases, and especially the bd-quinol oxidase, would have a crucial function by maintaining reducing conditions that permit PFOR to stay in its active state.

No MeSH data available.


Related in: MedlinePlus

Variability of the second doubling time for the four strains after oxygen exposure.Box and whiskers plot representing the variability in the distribution of the second doubling time of the various DvH strains cultured with constant 0.02% O2 gas mixture sparging followed by a switch to anaerobic condition. These distribution patterns arose from at least 2 independent cultures (> 200 cells each).
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pone.0123455.g006: Variability of the second doubling time for the four strains after oxygen exposure.Box and whiskers plot representing the variability in the distribution of the second doubling time of the various DvH strains cultured with constant 0.02% O2 gas mixture sparging followed by a switch to anaerobic condition. These distribution patterns arose from at least 2 independent cultures (> 200 cells each).

Mentions: The average values of the first division recovery time (time to recover a complete division event), calculated on at least 200 cells, were 6 hours for the Δbd mutant and about 5.3 hours for the three others strains (Table 2). When the same experimental protocol was performed on cells cultured under anaerobic conditions only (without any exposure to oxygen), the time to recover a complete division event was about 3 h for all strains (data not shown). The second doubling time (time to finish the second division event) was about 2.5 hours in average for the two single deletion mutants (Δbd and Δcox) and shorter for the Δcoxbd (2.1 hours) and the wild-type (1.9 hours) (Table 2). The distribution pattern showed that second doubling times for the single deletion mutant Δbd and Δcox strains were more scattered than that of the wild-type, with a significant proportion of cells exhibiting higher median, third quartile and maximum values. The distribution pattern of double deletion mutant Δcoxbd appeared closer to that of the wild-type strain, with less scattered values (Fig 6). These data show that even if cells were able to divide again when conditions were switched to anaerobic, it took longer to complete a division event when cells were previously exposed to constant 0.02% O2 sparging, the Δbd strain being the most affected. In addition the absence of either one of the membrane-bound oxygen reductase had a pronounced effect on the following division event, which was longer than for the wild-type strain.


Growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough under continuous low oxygen concentration sparging: impact of the membrane-bound oxygen reductases.

Ramel F, Brasseur G, Pieulle L, Valette O, Hirschler-Réa A, Fardeau ML, Dolla A - PLoS ONE (2015)

Variability of the second doubling time for the four strains after oxygen exposure.Box and whiskers plot representing the variability in the distribution of the second doubling time of the various DvH strains cultured with constant 0.02% O2 gas mixture sparging followed by a switch to anaerobic condition. These distribution patterns arose from at least 2 independent cultures (> 200 cells each).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383621&req=5

pone.0123455.g006: Variability of the second doubling time for the four strains after oxygen exposure.Box and whiskers plot representing the variability in the distribution of the second doubling time of the various DvH strains cultured with constant 0.02% O2 gas mixture sparging followed by a switch to anaerobic condition. These distribution patterns arose from at least 2 independent cultures (> 200 cells each).
Mentions: The average values of the first division recovery time (time to recover a complete division event), calculated on at least 200 cells, were 6 hours for the Δbd mutant and about 5.3 hours for the three others strains (Table 2). When the same experimental protocol was performed on cells cultured under anaerobic conditions only (without any exposure to oxygen), the time to recover a complete division event was about 3 h for all strains (data not shown). The second doubling time (time to finish the second division event) was about 2.5 hours in average for the two single deletion mutants (Δbd and Δcox) and shorter for the Δcoxbd (2.1 hours) and the wild-type (1.9 hours) (Table 2). The distribution pattern showed that second doubling times for the single deletion mutant Δbd and Δcox strains were more scattered than that of the wild-type, with a significant proportion of cells exhibiting higher median, third quartile and maximum values. The distribution pattern of double deletion mutant Δcoxbd appeared closer to that of the wild-type strain, with less scattered values (Fig 6). These data show that even if cells were able to divide again when conditions were switched to anaerobic, it took longer to complete a division event when cells were previously exposed to constant 0.02% O2 sparging, the Δbd strain being the most affected. In addition the absence of either one of the membrane-bound oxygen reductase had a pronounced effect on the following division event, which was longer than for the wild-type strain.

Bottom Line: Effect of constant low oxygen concentration on growth and morphology of the wild-type, single (Δbd, Δcox) and double deletion (Δcoxbd) mutant strains of the genes encoding these oxygen reductases was studied.Time-lapse microscopy revealed that a large majority of the cells were then able to divide (over 97%) but the time to recover a complete division event was longer for single deletion mutant Δbd than for the three other strains.We propose that the pyruvate-ferredoxin oxidoreductase (PFOR) plays a central role in this phenomenon by reversibly switching from an oxidative-sensitive fully active state to an oxidative-insensitive inactive state.

View Article: PubMed Central - PubMed

Affiliation: Aix-Marseille Université, CNRS, LCB-UMR7283, Marseille, France.

ABSTRACT
Although obligate anaerobe, the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough (DvH) exhibits high aerotolerance that involves several enzymatic systems, including two membrane-bound oxygen reductases, a bd-quinol oxidase and a cc(b/o)o3 cytochrome oxidase. Effect of constant low oxygen concentration on growth and morphology of the wild-type, single (Δbd, Δcox) and double deletion (Δcoxbd) mutant strains of the genes encoding these oxygen reductases was studied. When both wild-type and deletion mutant strains were cultured in lactate/sulfate medium under constant 0.02% O2 sparging, they were able to grow but the final biomasses and the growth yield were lower than that obtained under anaerobic conditions. At the end of the growth, lactate was not completely consumed and when conditions were then switched to anaerobic, growth resumed. Time-lapse microscopy revealed that a large majority of the cells were then able to divide (over 97%) but the time to recover a complete division event was longer for single deletion mutant Δbd than for the three other strains. Determination of the molar growth yields on lactate suggested that a part of the energy gained from lactate oxidation was derived toward cells protection/repairing against oxidative conditions rather than biosynthesis, and that this part was higher in the single deletion mutant Δbd and, to a lesser extent, Δcox strains. Our data show that when DvH encounters oxidative conditions, it is able to stop growing and to rapidly resume growing when conditions are switched to anaerobic, suggesting that it enters active dormancy sate under oxidative conditions. We propose that the pyruvate-ferredoxin oxidoreductase (PFOR) plays a central role in this phenomenon by reversibly switching from an oxidative-sensitive fully active state to an oxidative-insensitive inactive state. The oxygen reductases, and especially the bd-quinol oxidase, would have a crucial function by maintaining reducing conditions that permit PFOR to stay in its active state.

No MeSH data available.


Related in: MedlinePlus