Search

The effect of phosphorus on biosynthesis of polymyxin B by B. polymyxa 1538 was studied and its optimal concentration in the synthetic and two complex media was determined. Correlation between the culture growth and consumption of the main components, on the one hand, and concentration of phosphorus in the medium, on the other hand, was found. It was shown that the effect of phosphorus on biosynthesis of polymyxin B did not depend on the carbon source in the medium and aeration conditions.

The effect of some components of corn-steep liquor, such as biotin, organic nitrogen, inorganic phosphorus and other mineral elements on biosynthesis of polymyxin B by B. polymyxa, strain 1538 was studied. It was found that biotin and organic nitrogen had the most significant effect on the antibiotic accumulation. The effect of inorganic phosphorus and other mineral elements on accumulation of polymyxin by B. polymyxa, strain 1538 was less significant.

The effect of various concentrations of ammonium sulfate, sodium and potassium chlorides and sulfates on biosynthesis of polymyxin M by Bac. polymyxa Ross. on media containing wheet meal as the carbon source was studied. The culture growth, antibiotic accumulation and consumption of the main nutrients was studied as dependent on the level of the salts in the medium. The highest productivity was observed on media with the salt concentrations amounting to 1--2 per cent except sodium sulfate: changes in the concentration of the latter had practically no effect on the activity of the fermentation broth.

The effect of a number of the most important amino acids on the growth of B. polymyxa 1538 and polymyxin B biosynthesis was studied. It was found that all of the amino acids tested except D-L-threonin and L-alpha-gamma-DABA inhibited the initial growth of the organism. D-L-threonine and L-alpha-gamma-DABA had some stimulating effect on the culture growth without affecting the final accumulation of the biomass. The antibiotic synthesis proceeded more vigorously when the medium contained D-L-threonine, L-alpha-gamma-DABA, L-asparagine, L-proline, L-glutamine, D-L-asparaginic acid and L-glutamic acid in the concentrations tested. Neither of the tested amino acids used alone or in combination provided the levels of polymyxin B biosynthesis observed on the media containing rich sources of organic nitrogen.