Bacillus subtilis BS 107 as an antagonist of potato blackleg and soft rot bacteria.

Antimicrobial substances were produced by Bacillus subtilis BS 107 in a defined medium and isolated from culture filtrate by precipitation at pH 2.5. Active fractions were extracted in ethyl acetate, acetone, and 80% ethanol and purified by thin-layer chromatography (TLC) on silica gel plates developed with an ethanol-water mixture (2:1, v/v). In each case, a band with a Rf of 0.75 formed an inhibitory zone when the TLC plates were placed in contact with agar seeded with test cultures of the Erwinia spp. The antibiotic was released into the culture medium during early stages of growth of Bacillus subtilis BS 107 but higher amounts were released in older cultures. The antibiotic was resistant to the action of nucleases, proteases, and lipase. It was stable when autoclaved twice for 35 min at 2 atm (1 atm = 101.325 kPa) in acidic, neutral, and alkaline solutions. It remained active over the pH range of 1-14 during 1 month of observation and exhibited no loss of antimicrobial activity when stored at 4 degrees C for over 1 year. Bacillus subtilis BS 107 showed activity in vitro and in vivo against Erwinia carotovora subsp. atroseptica and Erwinia carotovora subsp. carotovora, the causal agents of potato blackleg and tuber soft rot. The application of an antagonist or its antibiotic to cut potato tissues prevented or reduced symptoms of the diseases. The antibiotic was active in vitro against a broad spectrum of bacterial and fungal species.

[The content of mimicry antigens in bacteria of the genus Klebsiella when they are cultured in plant tissue]. / Soderzhanie antigenov mimikrii u bakterii roda Klebsiella pri kul'tivirovanii ikh v rastitel'noi tkani.

Bacteria of genus Klebsiella were found to possess group-specific antigens of ABO system. Representatives of conditionally pathogenic species, K. rhinoscleromatis, K. pneumoniae, K. ozaenae, K. oxytoca, contain 9.4 to 38% of the antigens. In the process of interaction of plant organisms and Klebsiella, which passed three times in green tomato fruits, the latter have been found to influence some biological features of the bacteria which is manifested in the loss of the mimicry antigens by a considerable part of the strains as well as in developing capsules by some capsule-free variants of klebsiellae.

[The antagonistic activity of spore bacteria in relation to representatives of the genus Erwinia]. / Antagonisticheskaia aktivnost' sporovykh bakterii po otnosheniiu k nekotorym predstaviteliam roda Erwinia.

Strains of 26 species of genus Bacillus were examined for an antagonistic effect relative to erwiniosis agents: Erwinia amylovora, Erwinia carotovora, Erwinia chryzanthemi, Erwinia herbicola, Erwinia rhapontici. The Erwinia strain growth seized in the process of combined cultivation with microbes-antagonists. Practically all the studied strains of bacteria of genus Erwinia were sensitive to these or those Bacillus cultures. A considerable number of Erwinia strains studied were sensitive simultaneously to several cultures of Bacillus subtilis. The mechanism of action of antagonistic substances excreted by a definite strain of B. subtilis and damaging cells of bacteria of the Erwinia genus is studied. A damage of K+ ions' transport via cell walls of sensitive phytopathogenic bacteria after treatment of their cells with filtrates of culture liquid of active B. subtilis strain is found.

[The antimicrobial spectrum of the action of bacteriocins and bacteriophages from Klebsiella strains]. / Issledovanie antimikrobnogo spektra deistviia bakteriotsinov i bakteriofagov nekotorykh shtammov Klebsiella.

The percentage of bacteriocin-producing and phage-producing Klebsiella strains was as follows: K. pneumoniae-10%, K. ozaenae-7%, K. rhinoscleromatis-9%. The antimicrobial spectrum of the studied inducible particler was broad and was not limited by the frames of the genus and family. Bacteriocins and bacteriophages from Klebsiella were active to Klebsiella, Enterobacter, Escherichia, Shigella and Proteus representatives significant in medicine. Klebocins and Klebsiella phages exhibited antagonistic effects to phytopathogenic bacteria. Some strains of Erwinia and Pseudomonas were sensitive to phages or bacteriocins from Klebsiella. Bacteriocins protected corn and tomato seeds from contamination by erwinioses agents. All cultures of Agrobacterium, Corynebacterium, Micrococcus, Staphylococcus, Streptococcus were resistant to action of phages and klebocins. Bacteriocins from Klebsiella were assayed for their sensitivity to trypsin, chymotrypsin, lysozyme, ribonuclease, deoxyribonuclease. Action of klebocins was associated with a protein component. Proceeding from data of diffusion through the disc ultrafiltration membranes molecular weight of klebocins was in the range of 30,000 and 50,000 Da.