[Mapping a genetic determinant determining the increased synthesis of cholera toxin by the Dakka 35 strain of Vibrio cholerae].

A new mutation tox-2 defining the increased level of cholera exotoxin production by the strain Vibrio cholerae Dakka 35 isolated from nature has been mapped by conjugational crosses of donor and recipient strains differing by toxin production and serovar. The mutation has been localized on the chromosomal fragment containing the ilv, pur, ura, rfb genes adjacent to ura-94 locus. The linkage of the tox-2 mutation with the rfb locus coding for the synthesis of somatic Ol-antigen has been also established.