Integrative analysis of the biodegradation of acetone/isopropanol by Cupriavidus metallidurans CH34: proposal of a metabolic pathway

ABSTRACT: Various environmental bacteria were adapted to the presence of toxic and recalcitrant organic solvents. Cupriavidus metallidurans CH34, a β-proteobacterium that was found in industrial environments is known as a bacterial model to study heavy metal resistance. Interestingly, genome screening of CH34 also reveals the existence of genes involved in the degradation of recalcitrant organic solvents, such acetone and aromatic compounds. Here, we showed that this bacterium could resist a large variety of organic solvents, and was also able to metabolize some of them. In particular, investigations were focused on acetone and isopropanol catabolism. Integrative studies based on transcriptomic (DNA microarrays), proteomic (2D-DIGE and Isotope-Coded Protein Label technology) and biochemical analyses (enzyme purification and characterization) showed a similar catabolic pathway for both molecules which involved the AcxABC acetone carboxylase. First, isopropanol is oxidized into acetone by the Adh alcohol dehydrogenase. Acetoacetate production from acetone is then catalyzed by the acetone carboxylase. The generated acetoacetate molecules are then transformed by the PacIJ 3-oxoacid CoA-transferase, to acetoacetyl-CoA and succinate. Finally, an acetyl-CoA acetyltransferase catalyses the hydrolysis of acetoacetyl-CoA into 2 acetyl-CoA that are introduced into the glyoxylate cycle. As demonstrated, key enzymes of the acetone/isopropanol catabolism (encoded by acx and ald genes) are under the control of a σ54-dependent RNA polymerase. Moreover, the catabolic pathway involved in acetone and isopropanol consumption was repressed when gluconate was given as alternative carbon substrate, displaying a new example of diauxie. The results presented here provide a comprehensive picture of acetone and isopropanol biodegradation in Cupriavidus metallidurans CH34 and strongly support the fact that CH34 can be considered as a solvent tolerant bacterium.

ORGANISM(S): Cupriavidus metallidurans CH34

PROVIDER: GSE33578 | GEO | 2015/08/31

SECONDARY ACCESSION(S): PRJNA148575

REPOSITORIES: GEO