The Yersinia story

European Yersinia enterocolitica 4/O:3 produce two types of ¿-lactamases, enzyme A and enzyme B and belong to phage type VIII (4/O:3/VIII). Y. enterocolitica 4/O:3 isolated in Canada and Australia are identical producing only enzyme A and belonging to the same phage type IXb (4/O:3/IXb/A). Their failure to express enzyme B is due to same defect in ampC gene. When unusual European Y. enterocolitica 4/O:3 strains fail to produce enzyme B, it is invariably due to a different defect in ampC gene. The difference in defective ampC gene between European and Canadian/Australian 4/O:3 shows that the latter group did not derive from the former. The presence of the predominant and unique Y. enterocolitica subtype 4/O:3/IXb/A at two areas far apart on the earth can only be explained by a common geographical origin. This provides a microbiological proof of linkages between Paleoproterozoic and Mesoproterozoic geological features in north western Canada and Australia. The manuscript presents a new insight and perspective to both Geology and Microbiology.