Lactose utilization in Klebsiella pneumoniae: the slow utilization of lactose by resting cells of lactose fermenting strains.

Mutative lactose fermentation of lactose negative strains of Klebsiella pneumoniae to the lactose positive condition has been reported by Henriksen (1950) and Cabelli and Pickett (1953). The latter workers also demonstrated that the ability to ferment lactose was associated with a faster growth rate and with a greater resistance to the bacteriostatic action of the dye brilliant green, to the inhibitory effect of extreme pH ranges, and to the action of various antibiotics. It was also shown that mutations from the lactose negative to the lactose positive state resulted in a gain of all the associated characteristics. The present investigation was undertaken to study the mechanism of lactose utilization in K. pneumoniae as one approach towards ascertaining the basis for the linkage of characteristics controlled by what appears to be a pleiotropic gene.