Mapping of chromosomal genes that determine the El Tor biotype in Vibrio cholerae

Abstract

The El Tor biotype of Vibrio cholerae has several characteristics that differentiate it from the classical biotype of V. cholerae. Among these are production of soluble hemolysin(s), a cell-associated hemagglutinin for chicken erythrocytes, resistance to polymyxin B, and resistance to bacteriophages of Mukerjee group IV. In the present study, we located the determinants for hemolysin (hly), chicken erythrocyte hemagglutinin (cha), and polymyxin B resistance (pmx) on the genetic map of V. cholerae. Transposon-facilitated recombination was used to perform conjugal matings between El Tor donor strains and classical recipient strains of V. cholerae. Recombinants were selected that had inherited specific nutritional markers from the donor strains and streptomycin resistance from the recipient strains. The reconibinants were tested for the presence or absence of the unselected donor markers hly, cha, and pmx. These three El Tor biotype markers were found to be closely linked to each other and were located between the pyrA-201 and his-2 loci on the genetic map of V. cholerae.on July 31, 2020 by guest http://iai.asm.org/ Downloaded from

Transposon-mediated mutagenesis and recombination in Vibrio cholerae

“…The set of donor strains described here is capable of mobilizing any region of the V. cholerae eltor chromosome. A selected subset of these strains has recently been used to map the chromosomal locations of several eltor biotype markers (12).…”

Conversion of Vibrio eltor MAK757 to Classical Biotype: Role of Phage PS166

“…Incomplete con- version of biotype by phage CP-T1 was reported earlier by Ogg et al (1978), but phage PS166 mediates changes in all eltor-specific determinants, namely, production of soluble hemolysin, polymyxin B sensitivity, hemagglutination of chicken erythrocytes, and sensitivity to phage ⌽149, a phenomenon that is being reported for the first time. It is known that all eltor-specific determinants (hly, cha, pmx) are closely linked and located between the pyrA-201 and his-2 loci on the genetic map of V. cholerae (Green et al, 1983). It could be argued that the phage DNA may integrate at one position to pleotropically affect the expression of all of these determinants.…”

“…The observed conversion of the eltor biotype to the classical biotype indicated the suppression of all the eltor-specific characters (pmx, hly, cha). Because the genes for all of these determinants are known to be closely linked (Green et al, 1983), it may be conjectured that the integration of the phage genome took place at or near these loci and pleotropically affected their expression. Therefore the lysogens were plated on minimal agar plates supplemented with amino acids, nitrogenous bases (purine and pyrimidines), or vitamins to discover these auxotrophic requirements (Clowes and Hayes, 1968).…”

“…Within V. cholerae O1, the genetic map of the eltor biotype closely resembles that of the classical biotype (Johnson and Romig, 1979). The genetic determinants for the three eltor biotype markers, hemolysin (hly), chicken erythrocyte hemagglutinin (cha), and polymyxin B resistance (pmx), were found to be closely linked and located between the pyrA201 and his-2 loci on the genetic map of V. cholerae (Green et al, 1983). It was proposed that the pandemic strain of one biotype might arise from other biotypes of cholera Vibrio by transduction with a temperate phage or by mutation (Ogg et al, 1978).…”

Cloning of extracellular DNase and construction of a DNase-negative strain of Vibrio cholerae

“…Symbols: +, the selected donor allele was inherited at an increased frequency characteristic of Tfr; -, the selected donor allele was inherited at a low frequency. Previous studies provide examples of absolute numbers of recombinants observed in Tn5-mediated Tfr matings and an analysis of sites of insertion of transposons in Tfr donor strains (22,33). The site of insertion of transposon TnS in the chromosome of the donor strain JN1001 is the xds gene that encodes extracellular DNase.…”