The dismutation of aldehydes by a bacterial enzyme.

Formaldehyde-resistant Pseudomonas putida F61 isolated from a soil sample showed high activities of formaldehyde dehydrogenase (EC 1.2.1.1)and a specific enzyme catalyzing the dismutation of formaldehyde to form methanol and formate.The latter enzyme, given the trivial name of formaldehyde dismutase, was purified to electrophoretic homogeneity from a cell-free extract of P. putida F61.The enzymewas a tetramer with a molecular weight of approximately 2.2 x 105, and an isoelectric point of 4.8.The enzyme catalyzed the stoichiometric dismutation of formaldehyde and acetaldehyde to form a half mol of each of the corresponding alcohol and acid without addition of an electron acceptor, but it did not catalyze the dismutation of propionaldehyde, butyraldehyde and so on.The apparent Kmfor formaldehyde was found to be 350mM.Oneof the most unique properties of the enzyme was the catalytic activity of crossdismutation between two different aldehydes, such as formaldehyde/acetaldehyde, formaldehyde/ propionaldehyde, and so on.Formaldehyde occurs ubiquitously in nature in the process of microbial decomposition of organic compounds.It is known that several methylotrophs can utilize formaldehyde as a sole source of carbon and energy.1~4)On the other hand, some microorganisms have been reported to oxidize formaldehyde but not to assimilate it.5>6)In the preceding paper,6) we described that formaldehyde-resistant yeasts oxidized formaldehyde, which was used as an energy source during their growth on a medium containing glucose as a carbon source.Subsequently, we have examined formaldehyde oxidation by resistant bacteria which can grow on medium with 0.2% formaldehyde.