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Growth of Pseudomonas chloritidismutans AW-1(T) on n-alkanes with chlorate as electron acceptor.

Mehboob F, Junca H, Schraa G, Stams AJ - Appl. Microbiol. Biotechnol. (2009)

Bottom Line: Microbial (per)chlorate reduction is a unique process in which molecular oxygen is formed during the dismutation of chlorite.The key enzymes chlorate reductase and chlorite dismutase were assayed and found to be present.The oxygen-dependent alkane oxidation was demonstrated in whole-cell suspensions.

View Article: PubMed Central - PubMed

Affiliation: Wageningen University, The Netherlands.

ABSTRACT
Microbial (per)chlorate reduction is a unique process in which molecular oxygen is formed during the dismutation of chlorite. The oxygen thus formed may be used to degrade hydrocarbons by means of oxygenases under seemingly anoxic conditions. Up to now, no bacterium has been described that grows on aliphatic hydrocarbons with chlorate. Here, we report that Pseudomonas chloritidismutans AW-1(T) grows on n-alkanes (ranging from C7 until C12) with chlorate as electron acceptor. Strain AW-1(T) also grows on the intermediates of the presumed n-alkane degradation pathway. The specific growth rates on n-decane and chlorate and n-decane and oxygen were 0.5 +/- 0.1 and 0.4 +/- 0.02 day(-1), respectively. The key enzymes chlorate reductase and chlorite dismutase were assayed and found to be present. The oxygen-dependent alkane oxidation was demonstrated in whole-cell suspensions. The strain degrades n-alkanes with oxygen and chlorate but not with nitrate, thus suggesting that the strain employs oxygenase-dependent pathways for the breakdown of n-alkanes.

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Growth of strain AW-1Ta with decane and chlorate and b with decane and oxygen. Values are means of three replicates. The bars represent standard deviation. Dotted line with open circles represents the OD at 600 nm. The continuous lines represent (diamonds) chlorate utilized; (× marks) O2 utilization; (squares) chloride produced, and (triangles) bicarbonate formed
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Fig1: Growth of strain AW-1Ta with decane and chlorate and b with decane and oxygen. Values are means of three replicates. The bars represent standard deviation. Dotted line with open circles represents the OD at 600 nm. The continuous lines represent (diamonds) chlorate utilized; (× marks) O2 utilization; (squares) chloride produced, and (triangles) bicarbonate formed

Mentions: P. chloritidismutans AW-1T uses n-decane as a sole source of carbon and energy. Growth on n-decane and chlorate was indicated by the increase in optical density (Fig. 1a). An OD of 0.34 corresponds to a bacterial count of 1.31 × 109. Growth followed n-decane degradation as indicated by CO2 formation, chlorate reduction, and chloride production (Fig. 1a). No growth was observed in controls without inoculum or without n-decane or controls without chlorate (results not shown). The specific growth rate on n-decane and chlorate was 0.5 ± 0.1 day−1 (doubling time 1.4 ± 0.2 days). After 7 days, 87% of the 1 mM of the added n-decane was oxidized. The oxidation of 1 mM of n-decane led to a reduction of 9.2 ± 0.7 mM of chlorate and yielded 7.7 ± 0.6 mM of bicarbonate and 8.3 ± 0.8 mM of chloride. The balance fits relatively well with the theoretical stoichiometry of complete oxidation of n-decane coupled to chlorate reduction:1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$ {\text{C}}_{10} {\text{H}}_{22} + 10{\text{.33CIO}}_3^{ - } \to {\text{10HCO}}_3^{ - } + 10{\text{.33Cl}}^{ - } + {\text{H}}_2 {\text{O}} + {\text{10H}}^{+} $$\end{document}Fig. 1


Growth of Pseudomonas chloritidismutans AW-1(T) on n-alkanes with chlorate as electron acceptor.

Mehboob F, Junca H, Schraa G, Stams AJ - Appl. Microbiol. Biotechnol. (2009)

Growth of strain AW-1Ta with decane and chlorate and b with decane and oxygen. Values are means of three replicates. The bars represent standard deviation. Dotted line with open circles represents the OD at 600 nm. The continuous lines represent (diamonds) chlorate utilized; (× marks) O2 utilization; (squares) chloride produced, and (triangles) bicarbonate formed
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2690828&req=5

Fig1: Growth of strain AW-1Ta with decane and chlorate and b with decane and oxygen. Values are means of three replicates. The bars represent standard deviation. Dotted line with open circles represents the OD at 600 nm. The continuous lines represent (diamonds) chlorate utilized; (× marks) O2 utilization; (squares) chloride produced, and (triangles) bicarbonate formed
Mentions: P. chloritidismutans AW-1T uses n-decane as a sole source of carbon and energy. Growth on n-decane and chlorate was indicated by the increase in optical density (Fig. 1a). An OD of 0.34 corresponds to a bacterial count of 1.31 × 109. Growth followed n-decane degradation as indicated by CO2 formation, chlorate reduction, and chloride production (Fig. 1a). No growth was observed in controls without inoculum or without n-decane or controls without chlorate (results not shown). The specific growth rate on n-decane and chlorate was 0.5 ± 0.1 day−1 (doubling time 1.4 ± 0.2 days). After 7 days, 87% of the 1 mM of the added n-decane was oxidized. The oxidation of 1 mM of n-decane led to a reduction of 9.2 ± 0.7 mM of chlorate and yielded 7.7 ± 0.6 mM of bicarbonate and 8.3 ± 0.8 mM of chloride. The balance fits relatively well with the theoretical stoichiometry of complete oxidation of n-decane coupled to chlorate reduction:1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$ {\text{C}}_{10} {\text{H}}_{22} + 10{\text{.33CIO}}_3^{ - } \to {\text{10HCO}}_3^{ - } + 10{\text{.33Cl}}^{ - } + {\text{H}}_2 {\text{O}} + {\text{10H}}^{+} $$\end{document}Fig. 1

Bottom Line: Microbial (per)chlorate reduction is a unique process in which molecular oxygen is formed during the dismutation of chlorite.The key enzymes chlorate reductase and chlorite dismutase were assayed and found to be present.The oxygen-dependent alkane oxidation was demonstrated in whole-cell suspensions.

View Article: PubMed Central - PubMed

Affiliation: Wageningen University, The Netherlands.

ABSTRACT
Microbial (per)chlorate reduction is a unique process in which molecular oxygen is formed during the dismutation of chlorite. The oxygen thus formed may be used to degrade hydrocarbons by means of oxygenases under seemingly anoxic conditions. Up to now, no bacterium has been described that grows on aliphatic hydrocarbons with chlorate. Here, we report that Pseudomonas chloritidismutans AW-1(T) grows on n-alkanes (ranging from C7 until C12) with chlorate as electron acceptor. Strain AW-1(T) also grows on the intermediates of the presumed n-alkane degradation pathway. The specific growth rates on n-decane and chlorate and n-decane and oxygen were 0.5 +/- 0.1 and 0.4 +/- 0.02 day(-1), respectively. The key enzymes chlorate reductase and chlorite dismutase were assayed and found to be present. The oxygen-dependent alkane oxidation was demonstrated in whole-cell suspensions. The strain degrades n-alkanes with oxygen and chlorate but not with nitrate, thus suggesting that the strain employs oxygenase-dependent pathways for the breakdown of n-alkanes.

Show MeSH
Related in: MedlinePlus