Restriction endonuclease digest patterns of chromosomal DNA from nitrate-negative Campylobacter jejuni-like organisms

High molecular weight chromosomal DNA was isolated from ten nitrate-negative campylobacters of human origin (gastric biopsies and faecal specimens). The DNA was digested with various restriction endonucleases and the patterns obtained were compared with those of Campylobacter coli, C. fetus subsp. fetus, C. jejuni and C. laridis reference strains. Electrophoresis of Hae III digests of DNA in 0.5% agarose gave excellent patterns which comprised at least 25 well-resolved bands with fragment sizes between about 4 and 40Kb. There were distinct differences between strains from different geographical locations. The six gastric strains from West Germany formed a relatively homogeneous group with respect to their band patterns (type I and II), whereas the U.K. gastric isolate had a slightly different pattern (type III) as did the three Australian faecal isolates (types IV, V and VI). No plasmids were detected in these nitrate-negative campylobacters and differences in DNA digest patterns between strains and representatives of allied species were attributed to variations in the distributions of Hae III recognition sequences within the genome. The patterns provided further evidence that the strains were atypical C. jejuni.