The study identified and characterized two beta-lactamase genes, asbA1 and asbB1, from Aeromonas sobria AER 14M. These genes encode enzymes capable of hydrolyzing various beta-lactam antibiotics, including cephalosporins and penicillins. Additionally, the research highlighted the necessity of an E. coli chromosomal mutation for the efficient expression of the class D enzyme, asbB1.