Nutrition and Metabolism of Marine Bacteria XV. Relation of Na + -Activated Transport to the Na + Requirement of a Marine Pseudomonad for Growth

Abstract

A marine pseudomonad was found to require 50 to 100 m[image] Na+ for maximal rate of oxidation of D-galactose and for the transport of D-fucose-H3 into the cells. The same organism required 150 to 200 m[image] Na+ for the oxidation of L-alanine and for the transport of [alpha]-aminoisobutyric acid-C14 (AIB-C14) into the cells. Competition studies indicated that D-galactose and D-fucose on the one hand and L-alanine and AIB on the other shared common carriers for transporting the compounds into the cells. This parallelism in Na+ response for oxidation and transport extended to growth when L-alanine was the sole carbon source in the medium. When D-galactose was the sole carbon source, an amount of Na+ equal to that with L-alanine was needed. KCN and dinitrophenol but not ouabain inhibited the uptake of AIB-C14 by the cells. K+ in addition to Na+ was required for transport, and both Mg++ and either Cl- or Br- were stimulatory. Photobacterium fischeri was also found to require Na+ specifically for the uptake of AIB-C14 by the cells.