A fast screening method for surface layers on Gram-positive bacteria

A two-step screening method is described to identify regularly arranged sur face layers (S layers) on Gram-positive bacterial strains. A non-destructiv e release of S-layer sheets is achieved by enzymatic hydrolysis of the unde rlying peptidoglycan using lysozyme. The existence of regular S layers is t hen directly confirmed by scanning force microscopy or transmission electro n microscopy. This method requires a minimal amount of bacterial cells and may be used as a `quick test' for demonstrating the presence of S layers.