CHARACTERIZATION OF THE PLASMID PMB1 FROM BIFIDOBACTERIUM-LONGUM AND ITS USE FOR SHUTTLE VECTOR CONSTRUCTION

The nucleotide sequence of the 1847-bp Bifidobacterium longum B2577 cr yptic plasmid pMB1 was determined. The plasmid had a G+C content of 62 .0%, and contained two open reading frames, orf1 and orf2, likely arra nged in an operon. The proteins encoded by orf1 and orf2 show the high est degree of similarity with similarly arranged peptide sequences tra nslated from Corynebacterium glutamicum pXZ10142 and Mycobacterium for tuitum pAL5000 plasmids. Recombinant plasmids containing the pMB1 repl icon were able to replicate in Bifidobacterium animalis MB209. The suc cessful transformation of this strain with pMB1-based plasmids facilit ated characterization of this replicon, results of which showed that b oth orf1 and orf2 are necessary for plasmid replication, A family of n ew Escherichia coli-B. animalis shuttle plasmids, based on the pMB1 re plicon and expressing a cat and an ery gene, was constructed.