Stereoselective reduction of cobalt(III) complexes by bacteria

Area of Science:

• Microbiology
• Biochemistry
• Inorganic Chemistry

Background:

• Cobalt(III) complexes are important in coordination chemistry.
• Microbial reduction of metal complexes can be stereoselective.
• Enterobacter cloacae is a soil bacterium with potential metabolic capabilities.

Purpose of the Study:

• To investigate the stereoselective reduction of triglycinatocobalt(III) by Enterobacter cloacae.
• To compare the reduction capabilities of whole cells and cell-free extracts.
• To explore the influence of different conditions on the stereoselectivity of the reaction.

Main Methods:

• Anaerobic incubation of Enterobacter cloacae with racemic triglycinatocobalt(III).
• Preparation and use of washed cell suspensions and cell-free extracts.
• Analysis of stereoselectivity under argon and molecular hydrogen atmospheres.

Main Results:

• Enterobacter cloacae reduced the L-enantiomer stereospecifically under argon.
• Cell disruption with 2-phenylethanol increased the reduction rate and showed a slight preference for the D-enantiomer.
• Cell-free extracts exhibited similar stereoselectivities to disrupted cells but also reduced the D-enantiomer stereoselectively under molecular hydrogen.

Conclusions:

• Enterobacter cloacae possesses stereoselective mechanisms for reducing cobalt complexes.
• Cellular components and environmental conditions significantly influence the stereochemical outcome.
• The findings suggest potential applications in biocatalysis and asymmetric synthesis.