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Sensitivity of 84 cultures of L. fermenti, 43 cultures of L. brevis, 13 cultures of L. buchneri and 2 cultures of L. cellobiosus to the effect of 39 types of bacteriocins produced by various species of lactobacilli was studied with the method of delayed antagonism. All the cultures of L. brevis, L. buchneri and L. cellobiosus and 65.5 per cent of the cultures of L. fermenti were sensitive to one or more such bacteriocins. The cultures of L. Fermenti, L. brevis, L. buchneri and L. cellobiosus were sensitive respectively to 37, 19, 16 and 9 types of the bacteriocins out of 39 types tested.

Antibacterial activity of 272 Erwinia strains was studied. It was found that 182 or 66.9 per cent of the strains were capable of producing spontaneously antibacterial substances belonging to the class of bacteriocins; 125 bacteriocynogenic strains were divided into 25 groups on the basis of their antibacterial spectrum similarity; 57 bacteriocynogenic strains were not included into any of these groups because of their significant heterogenicity with respect to the feature studied. It was shown that most of the strains inhibited viability of the bacteria of both its own and other species. Investigation of the antagonistic activity of the Erwinia strains with broad antibacterial spectra with respect to E. coli indicative for colicins gave negative results. The study of the Erwinia strains sensitivity to the antibacterial effect of the bacteriocynogenic cultures showed that 210 out of 272 cultures were sensitive to separate bacteriocins.

Capacity for production of bactericin was found in the spheroplasts of the strains of the rodent pseudotuberculosis microbe. The author named it as pseudotuberculocin. The bacteriocin production was not detected in the initial strains of the pseudotuberculosis microbe. Pseudotuberculocin differed in the antibacterial spectrum and morphology of the growth inhibition zones formed on the plates with the indicator strains from the pesticins produced by the strains of the plaque microbe of the marmot and sandword varieties respectively and the cultures of the plaque microbe from the Transcaucasian Upland, as well as from pesticins of the spheroplasts of these strains. Production of a pesticin differing from pesticins of the rod-like forms of these strains by an ability to inhibit the growth of the homologous indicators was shown in the spheroplasts of the plaque microbe of the marmot and sandword varieties. Sensitivity of the plaque microbe strains of the marmot and sandword varieties to the pesticins of the plaque microbe strains and pseudotuberculocin was noted. With an account of the difference in the activity of the tested pesticins and pseudotuberculocin against the strains of the Frederic collection it is recommended to use this property for identifications of pesticins and pseudotuberculocin.