Oxidation of organic C1 compounds byHyphomicrobium spp.

Washed cell suspensions ofHyphomicrobium spp. were able to oxidize methanol, formaldehyde and formate. This suggested that enzymes for the oxidation of these compounds were present. The pathway of the oxidation of methanol to carbon dioxide and water has been investigated using cell-free extracts. An ammonium-ion-activated, phenazine methosulphate-linked methanol dehydrogenase was detected. This enzyme has a dual substrate specificity for normal primary alcohols and formaldehyde. It has a high pH optimum for activity of 9.5. The pathway is completed by an NAD-linked formate dehydrogenase. This enzyme is inhibited by low concentrations of potassium cyanide, copper sulphate and hypophosphite.