PATHWAYS OF PRIMARY AND INTERMEDIATE METABOLISM IN A PSYCHROPHILIC METHANOTROPH

The enzymes of primary and intermediate metabolic pathways were studie d in a psychrophilic methanotroph having an optimal growth temperature lower than 15-degrees-C. The strain was shown to oxidize methane to C O2 via methanol, formaldehyde, and formate by means of corresponding d ehydrogenases. Assimilation of methane carbon occurs at the level of f ormaldehyde via the ribulose monophosphate cycle. Ammonium nitrogen is assimilated via the glutamate cycle and via reductive amination of py ruvate by means of alanine dehydrogenase. Although strain Z-0021 has s ome properties of group X of methanotrophs, it was assigned to group I according to the set of enzymes of carbon metabolism. The activities of all the studied enzymes of the psychrophilic methanotroph decreased substantially as the temperature was lowered.