The effect of cell wall components on glycine-enhanced sterol side chain degradation to androstene derivatives by mycobacteria

beta-Sitosterol side chain degradation by Mycobacterium sp. NRRL MB 3683 re sults in the formation of androstene derivatives and is increased in the pr esence of glycine. As the sterol transformation is carried out inside the c ell, higher product accumulation could indicate faster diffusion of highly hydrophobic substrate through the cell wall permeability barrier. Cell wall preparations were obtained to analyse the effect of glycine on peptidoglyc an components. Peptidoglycan is known to be the target for glycine action. In glycine-treated preparations, the molar ratio of diaminopimelic acid:mur amic acid, the marker compounds of tetrapeptides and glycan strands respect ively, was about 60% lower than in the control. This indicates a possible r eduction in cross-linking between peptide units and the destruction of pept idoglycan. Unexpectedly, glycine also caused changes in the relative propor tion of mycolic acids to other lipids occurring in the strain used for this study. The enhancement of beta-sitosterol side chain degradation is likely to result from disturbing the integrity of the cell wall components respon sible for the permeability barrier in mycobacteria.