Abstract
Yersinia enterocolitica biogroups 3A and 3B are biochemically, serologically, and ecologically different from biogroup 3 and other Y. enterocolitica biogroups. Both biogroup 3A and biogroup 3B can be characterized by their negative Voges-Proskauer reactions and positive reactions in tests for pyrazinamidase, acid production from mucate, proline peptidase, and acid production from D-xylose. Biogroup 3A ferments L-sorbose but not L-fucose; biogroup 3B has the opposite fermentation pattern. Deoxyribonucleic acid relatedness studies (hydroxyapatite method) indicated that biogroups 3A and 3B are two new species that are about 55% interrelated and 25 to 46% related to other Yersinia species (except Yersinia ruckeri [20 to 22%]). The names Yersinia mollaretii sp. nov. and Yersinia bercovieri sp. nov. are proposed for biogroups 3A and 3B, respectively.