Specifically catalyzes the hydrolysis of 6-aminohexanoic acid cyclic dimer (1,8-diazacyclotetradecane-2,9-dione) to form the linear dimer 6-aminohexanoyl-6-aminohexanoic acid. Is inactive on 6-aminohexanoic acid oligomers (degree of polymerization 2 to 6), various other cyclic amides, cyclic diamides, linear amides, oligopeptides, and casein. Allows the bacterium to grow on a medium containing 6-aminohexanoic acid cyclic dimer as the sole carbon and nitrogen sources