Characterization of the gene encoding the β-lactamase of the psychrophilic marine bacterium Moritella marina strain MP-1

The beta -lactamase gene (mbla) of the psychrophilic marine bacterium Moritella marina strain MP-1 was identified in a previously isolated genomic DNA fragment and it was expressed in Escherichia coli cells. The mbla gene encoded a protein consisting of 287 amino acid residues, Its predicted amino acid sequence showed approximately 50% identity with that of a number of class A beta -lactamases, especially with that of CARB/PSE type of beta -lactamases (carbenicillinases). E, coli transformed with the plasmid containing mbla grew on an ampicillin-containing plate at 37 degreesC but not at 42 degreesC, suggesting that the beta -lactamase of this bacterium is heat-labile.