BACKGROUND: Pharmaceutical companies continue to evaluate ss-amino acids and ss-lactams in a range of drug candidates. The development of a highly efficient and selective bioresolution of cyclic ss-lactam substrates could yield enantiopure lactams and ss-amino acids with medicinal potential. The aim of this work was to discover and develop a biocatalyst capable of selectively hydrolysing ss-lactam substrates. RESULTS: Screening of our in-house culture collection led to the discovery of a microorganism, Rhodococcus globerulus (NCIMB 41042) with P-lactamase activity. Whole-cell bioresolutions of the ss-lactams 1-4 were successfully carried out and in all cases enantiomeric excesses of the residual lactam and amino acid product were found to be greater than 98%. For one example, the bioresolution was optimised to operate at 60 g L-1 substrate concentration with a 20% wt/wt cell paste loading. CONCLUSIONS: A microorganism, Rhodococcus globerulus (NCIMB 41042), capable of selectively hydrolysing a range of cyclic ss-lactams, has been discovered. A scalable whole-cell bioresolution process has been developed, leading to the synthesis of multigram quantities of enantiomerically pure ss-lactams and ss-amino acids. (c) 2007 Society of Chemical Industry.