GENETIC DETERMINATIONS OF THE O-ANTIGENS 6, 8 AND 20 IN <I>SALMONELLA</I> GROUP C

1. The genetic determinations of the O antigens of Salmonella were studied using Hfr or F' croses between strains of groups B (S. abony : O-1, 4, 5, 12 ; S. paratyphi B var. odense : O-1, 4, 12) and C₂ (S, newport var. puerto-rico : O-6, 8). The main genetic determinants of the antigens 4, 12 of group B and 6, 8 of group C₂ behaved as alleles of one locus in so-called O, close to his locus. The gene O-5 was also linked to his locus. <BR>2. S. Paratyphi B var. odense (native O antigens 1, 4, 12) of group B which received O-6, 8 from S. newport var. puerto-rico (O-6, 8) of group C₂, produced P 22 (iota) without manifestation of O-1, but O-1 was produced after transfer of O antigens 4, 12 or 4, 5, 12 from S. paratyphi B 8006 (O-4, 5, 12) of group B or of O antigens 9, 12 from S. typhi H 901 W (O-9, 12) of group D. The fact was considered that O-1 may be produced through the action of phage P 22 (iota) in co-operation with the substance of O-12. <BR>3. The genetic determination of the O antigens of Salmonella was also studied using Hfr or F' reciprocal crosses between strains of groups B (S. abony : O-1, 4, 5, 12 or S. paratyphi B var. odense : O-1, 4, 12) and C₃ (S. emek : O-(8), 20). The main genetic determinants of the antigens 4, 12 of group B and (8) of group C₃ behaved as alleles of one locus, called O-4, 12/(8) , and were found to be closely linked to his locus.<BR>4. In crosses of a group B donor (S. abony : O-1, 4, 5, 12) with group C₃ recipients (S. emek : O-(8), 20), loss of O-20 from the recipients appeared in some of the recombinants which had received leu⁺, pro⁺, nic⁺, trp⁺ or lys⁺ marker of the group B donor. When another crosses were made between group C₃ (S. emek: O-(8), 20) donor strain and recipient strains that had been isolated as a his⁺ and O-(8) positive recombinat from a cross between group C₃ (S. emek : O-(8), 20) donor and a group B (S. paratyphi B var. odense : O-1, 4, 12) recipient, some of pro⁺ or nic⁺ recombinants in the crosses received the O-20 gene from the group C₃ donor strain. These results suggest that the determinant of somatic antigen 20 was fouud to be closely linked to the pro and nic gene. <BR>5. An Hfr strain of group B (S. abony : O-1, 4, 5, 12) was crossed with an F-strain of group C₂ (S. newport var. puerto-rico : O-6, 8) or group C₃ (S. emek : O-(8), 20). When recombinants with his locus from the donor were selected, most of them differed serologically from both of parents and formed semirough forms. These semirough recombinants were intermediate between S and R forms giving smooth-looking colonies, growing with deposit in broth, being unstable in saline suspension, and possessing the specificities 4 and 12, or 4, 5 and 12.