Microbial growth on C-1 compounds. 6. Oxidation of methanol, formaldehyde and formate by methanol-grown Pseudomonas AM-1

The complete oxidation of methanol to carbon dioxide in cell-free extracts of methanol-grown Pseudomonas AM 1 was investigated. By using 3-amino-1,2,4-triazole, a known inhibitor of catalase, the independence of methanol oxidation from catalatic activity was shown. The only enzyme capable of oxidizing methanol that could be demonstrated was a dehydrogenase that can be linked to phenazine methosulphate and required the presence of NH4(+) ions. An aldehyde dehydrogenase that reduced 2,6-dichlorophenol-indophenol or phenazine methosulphate in the presence of formaldehyde was found in cell-free extracts and was purified. A nicotinamide-adenine nucleotidelinked formate dehydrogenase was found in cell-free extracts and purified. The possible significance of these enzymes in the oxidation of C-1 substrates by intact cells is discussed. Cell-free extracts of methanol-grown Protaminobacter ruber, Pseudomonas extroquens and Pseudomonas methanica have been found to possess a methanol dehydrogenases similar to those found in Pseudomonas AM 1. A specific nicotinamide-adenine dinucleotidelinked formaldehyde dehydrogenase was found in high activity in extracts of methanol-grown Pseudomonas methanica, in lower activity in extracts of methanolgrown Pseudomonas extorquens and Protaminobacter ruber.