The Gram-Staining Reaction of Disintegrated Micro-organisms652

Summary: Disintegration of yeast and Clostridium welchii gave cell envelopes which stained Gram-negative by a modified Jensen’s Gram-staining procedure (procedure 1), but stained in part Gram-positive by a modification of the Gram stain in which the films were dried after application of the iodine and before application of the decolorizing agent (90% v/v ethanol; procedure 2). Procedure 2 appeared to give a typical Gram reaction in that a series of organisms gave identical results when stained by the two procedures. Disintegrated Gram-negative organisms gave only Gram-negative material when stained by procedure 2. The Gram-positive material could be removed from the yeast envelopes by extraction at pH 8, but attempts to ‘replate’ the envelopes with the extract were unsuccessful. The results suggest that the Gram-staining reaction of yeast and C. welchii is due in part to a specific staining component and in part to a factor dependent upon the intact nature of the cells. The latter may be associated with the stability or orientation of the staining component or with some membrane effect.