[Biological properties of a Bacillus brevis 101 mutant]. / Biologicheskie osobennosti mutanta Bacillus brevis 101.

Some features of the Bacillus brevis 101 mutant producing the antibiotic gramicidin S are described. The mutant is very close to the initial P+-variant of Bacillus brevis var. G-B by cultural, physiological and biochemical characteristics. The most typical features of Bacillus brevis 101 are high antibiotic activity (up to 2 g/l) and the specific phenotype of the colonies. The phenotypical features of Bacillus brevis 101 are dependent on the conditions of its cultivation. On minimal media rich in organics a change of the culture correlated with a lower antibiotic activity.

[Interaction of gramicidins with the cellular phospholipids of the producer Bacillus brevis]. / Vzaimodeistvie gramitsidina S s fosfolipidami kletok produtsenta Bacillus brevis.

Phospholipid fractions were isolated from the cells of Bacillus brevis var. G.-B. variants, some, of which produced gramicidin S and some did not. As was found by thin layer chromatography, phosphatidyl ethanolamine predominated in the fraction of phospholipids. Interaction of the isolated phospholipids with gramicidin S in vitro resulted in a loss of the antibiotic activity. Presumably, formation of a complex between the polypeptide and phospholipids may decrease the actual concentration of gramicidin S in cells producing the antibiotic.

[Role of gramicidin S in the sporulation of the R+ and R- variants of Bacillus brevis var. G.-B]. / Rol' gramitsidina S v sporoobrazovanii R+ i R- variantov Bacillus brevis var. G.-B.

The effect of gramicidin S added to the cultivation medium on sporulation of the gramicidin S-producing P+ variant and gramicidin S-nonproducing P- variant of Bacillus brevis var. G.-B. was studied. Gramicidin S added to the synthetic medium with glucose in an amount of 30 and 100 microgram/ml 4 and 7 hours after inoculation with the vegetative cells of R- variant had no effect on the growth of the culture but retarded its sporulation. When gramicidin S was added in an amount of 100 microgram/ml 4 hours after inoculation, the sporulation rate of R- variant strongly decreased, rohile sporulation was not suppressed as it was noted before with respect to R+ variant. Active stimulation of Bacillus brevis var. G.-B. sporulation was observed after addition of gramicidin S 13 hours after development of R+ and R- variants without the antibiotic biosynthesis. Synthesis of gramicidin S by R+ strain was suppressed by the specific inhibitor beta-phenyl-beta-alanine. The amount of gramicidin S added to the medium during the sporulation process of R+ and R- variants decreased. On addition of 30 microgram/ml of the antibiotic it was practically not detectable when the culture showed the greatest number of the spores. Therefore, gramicidin S added to the medium is probably adsorbed by the cells of Bac. brevis var. G.-B. and affects sporulation of R- and R+ variants thus accelerating or retarding this process depending on the cultivation conditions.