[Recipient capacity of B. alcalescens strains in the conjugation transfer of R-factors to them for E. coli strains].

Unlike many enterobacteria the strains of B. alkalescens isolated from patients with the intestine dysfunction and healthy persons preserved sensitivity to the antibiotics used in the medical practice. This served as a basis for the study of the recipient competence for reception of R-factors from E. coli by 6 strains of the alkali producer. The strains of E. coli with the derepressive R-factors J 5-3 R1, J 5-3 R64 and CSH-2 R1-19 were introduced into the conjugation mixture as the donors. Only I strain of E. coli, i.e. J 5-3 R1 with multiple antibiotic resistance proved to be a competent donor. A possibility of transfering on1 I determinant of resistance (to neomycin) to 3 out of 6 strains of B. alkalescens at a low rate of10-7 and 10-9 was shown. The R+ conjugants appeared to be immune to further reception of R-factors of both the competent and the incompetent donors. The low recipient capacity of the strains of B. alkalescens must, to some extent promote circulation mainly of antibiotic sensitive strains of the microbes under natural conditions.