REDUCTION OF TETRAZOLIUM SALTS TO FORMAZANS IN FUSOBACTERIUM POLYMORPHUM

The sites of reduction of tetrazolium salts in cells of a strain of Fusobacterium Polymorphum was investigated by means of light microscopy and electron microscopy. The formazans of triphenyltetrazolium chloride were demonstrated to occur as relatively large crystal-shaped depositions in the cytoplasm. As these granules, usually a few in number, seemed to be formed secondarily by the intracellular aggregation of small granules primarily formed in the cytoplasm, it was almost impossible to localize the initial sites of TTC reduction in the cytoplasm. On the contrary, nitrobluetetrazolium formazans were proved to deposit very close to the cytoplasmic membrane and the intracytoplasmic membrane system. These observations strongly suggest that the site of oxidation-reduction activity may be associated with the cytoplasmic membrane and the intracytoplasmic membrane system which have recently been found in various Actinomycetes and Eubacteria.