STAINING PROPERTIES OF ISOLATED MYCOBACTERIAL CELLULAR COMPONENTS AS REVEALED BY ZIEHL-NEELSEN PROCEDURE

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Abstract
Tubercle bacilli were mechanically disrupted and separated into 3 cellular components: cell-wall fraction, intracellular particulate fraction, and soluble fraction. None of the components was acid fast when stained by the Ziehl-Neelsen technique, although the intracellular particulate material and the cytoplasmic fluid had a marked affinity for the carbolfuchsin whereas the isolated cell walls did not. The same 3 cellular components were isolated also from tubercle bacilli previously stained by the Ziehl-Neelsen method. The results indicated that the stained sites were inside the cell-wall structure, since the isolated cell walls were not colored whereas the other 2 fractions were. These observations support the theory that lack of permeability is responsible for the retention of carbolfuchsin in the acid-fast staining procedure. It also follows from these findings that the acid-fast stain is an excellent procedure for testing the purity of mycobacterial cell-wall preparations.