Genetics of Campylobacter and Helicobacter.

This article reviews the current state of genetic analysis of Campylobacter and Helicobacter. Chromosomal genes cloned from Campylobacter and Helicobacter species are listed along with the method used to identify the cloned gene. Campylobacter plasmid genes that have been cloned and expressed in Escherichia coli and that specify resistance to tetracycline, kanamycin, or chloramphenicol are presented. This review also examines our current knowledge of genetic exchange in Campylobacter, including conjugative plasmid transfer, natural transformation, electrotransformation, and bacteriophage transduction. In Helicobacter, natural transformation has been described and both plasmids and bacteriophages have been observed. Plasmid cloning vectors have been constructed for Campylobacter. Available vectors are discussed and restriction maps of some useful vectors that we have constructed are included. The genome sizes of C. jejuni and C. coli are approximately 1.7 megabases (Mb), whereas the genome size of H. pylori ranges from 1.60 to 1.73 Mb. The positions of various genes on the C. jejuni and C. coli genome maps have been determined using both homologous and heterologous DNA probes. Genomic maps of these organisms are presented.