Lactose Utilization by Pseudomonas maltophilia

The type species (ATCC 13637) and one other strain (ATCC 17444) of Pseudomonas maltophilia have been examined for their ability to use the disaccharide lactose for growth. These organisms lack the usual high levels of β-galactosidase found in most lactose-positive bacteria, although both strains were found to have high levels of the enzyme lactose dehydrogenase. If this latter enzyme is responsible for all lactose splitting, P. maltophilia is unlike other pseudomonads, which have lactose dehydrogenase but which apparently cannot use lactose as a source of carbon and energy for growth.