Active transport of choline by a marine pseudomonad.

A marine pseudomonad, BAL-31, accumulates the phospholipid nitrogen base, choline, although no detectable amount of choline is incorporated into polar lipids. Metabolic inhibitors such as cyanide and azide block the uptake process as does starving for oxygen by using nitrogen gas. Only very close structural analogues show any inhibition of transport, indicating that the uptake process has great structural specificity. The export of choline out of the cells is also an energy-dependent process and is markedly reduced during oxygen depletion. The constitutive level of choline transport is increased by approximately a factor of three after a brief induction period. Two other gram-negative bacteria also accumulate choline, whereas a gram-positive bacterium, Bacillus subtilis, and a yeast, Saccharomyces cerevisiae, fail to show any detectable accumulation.