[Effect of K+ ions on Bac. polymyxa 153 growth and the biosynthesis of polymyxin B].

The growth of Bac. polymyxa, 153 producing polymyxin B did not change under the effect of various concentrations of potassium ions, while the antibiotic productivity of the cells significantly decreased. A great amount of polymyxin is excreted by the bacteria into the fermentation broth and a certain portion of the antibiotic remains in the cells. Under the experimental conditions the potassium salts slightly changed the pH value of the fermentation broth and probably did not affect polymyxin secretion from the cells into the fermentation broth.