[Phenotypic expression of plasmid pPL7065 in Bacillus pumilus in free and integrated states]. / Izuchenie fenotipicheskogo vyrazheniia plazmidy pPL7065 Bacillus pumilus v svobodnom i integrirovannom sostoianii.

There are about 20 copies of pPL7065 plasmid in cells of Bacillus pumilus ATCC7065 with molecular weight of 4.7 X 10(6) daltons. A spontaneous purine dependent mutant LK1 was isolated which contained no autonomous plasmid. However, the presence of the plasmid in LK1 cells was proved by DNA - DNA hybridization. To accomplish this, hybrid plasmid p1G1 was constructed by cloning pPL7065 on a vector pBR322 and multiplying it in Escherichia coli C600. The plasmid then was hybridized with chromosomal DNA of Bac. pumilus LK1. A pur+ revertant has been obtained from LK1 containing autonomous plasmid pPL7065, similar to the parental strain ATCC7065. These results are indicative of pPL7065 integrated into the chromosome of LK1. Bacteria having the autonomous plasmid are oligosporogeneous and produce specific antibiotics. Integration of the plasmid into bacteria causes pur phenotype, normal sporulation and a change in antibiotic synthesis and resistance. LK3 strain which lost pPL7065, sporulates normally and produces the antibiotic that inhibits growth of Bac. pumilus ATCC7065.

[Changes in Bacillus pumilus antibiotic activity and sensitivity with integration and disintegration of plasmid pPL 7065]. / Izmenenie antibioticheskoi aktivnosti i chuvstvitel'nosti u bacillus pumilus pri integratsii i dezintegratsii plazmidy pPL 7065.

The role of plasmid pPL 7065 in the control of the antibiotic production and sensitivity in Bac. pumilus was studied with the use a plasmid-free strain and strains containing the plasmid in the cells in a free or chromosome-integrated state. It was found that all the strains had antibiotic activity only with respect to a limited number of gram-positive bacteria. Still, the antibiotics produced by them differed in the antibacterial spectrum. The antibiotic produced by the plasmid-free strain had a broader spectrum. It was shown that the bacteria with the plasmid in th free state were sensitive to the antibiotics produced by the plasmid-free strain for the strain or the strain with the chromosome-integrated plasmid. It was suggested that plasmid pPL 7065 played the role of a modifier of the antibiotic activity and sensitivity in Bac. pumilus and carried no genetic information for the control of the antibiotic synthesis. Their formation is determined by the chromosome genes.

[Integrative suppression of antibiotic formation in Bacillus pumilus]. / Integrativnaia supressiia antibiotikoobrazovaniia u Bacillus pumilus.

Relationship between antibiotic production and pPL 7065 plasmid integration into the chromosome of B. pumilus ATCC 7065-K was studied. With this purpose hybridization of plasmid DNA isolated from strain ATCC 7065 producing no antibiotic was performed with chromosome DNA of B. pumilus ATCC 7065 and W20, as well as B. subtilis and E. coli K-12. Plasmid DNA labeled with 3H was used in the experiments. It was found to be slightly bound with DNA of B. subtilis (0.8 per cent), E. coli K-12 (0.2 per cent), and B. pumilus W20 (3 per cent). Still, its hybridization with chromosome DNA of B. pumilus ATCC 7065-K was effective (11 per cent). It is concluded to be due to hybridization between plasmid pPL 7065 of strain ATCC 7065 and the same plasmid but integrated into the chromosome of the antibiotic-producing strain ATCC 7065-K. Therefore, derepression of the antibiotic biosynthesis is a sequence of integrative suppression.

[Antibacterial activity and bacteriophages of Bacillus pumilus]. / Antibakterial'naia aktivnost' i bakteriofagi Bacillus pumilus.

Inducable defective phages analogous to those in Bac. subtilis were found in 5 strains of Bac. pumilus, 3 of which possessed antibacterial activity. A moderate bacteriophage was also induced in addition to the defective phage in strain ATCC 12140 not producing the antibiotic. It was found that the antibacterial activity was not associated with the presence of phages in the cultures. The data on the electron microscopic investigations are presented.

[Antibiotic formation in plasmid and plasmid-free strains]. / Antibiotikoobrazovanie u plazmidnykh i besplazmidnykh shtammov.

Antibiotic activity of three plasmid and three plasmid-free strains of Bacillus pumilus was studied. The antibiotic activity was found in one plasmid and two plasmid-free strains. It was supposed that both the chromosomic and extrachromosomic genes could participate in regulation of the antibiotic production in Bac. pumilus. It was shown that the antibiotics produced by Bac. pumilus had a very narrow spectrum and inhibited multiplication only of several grampositive bacteria.