A Study of Thiobacillus thiooxidans with the Electron Microscope.

Thiobacillus thiooxidans, an obligate autotrophic sulfur-oxidizing bacterium, has received considerable attention because of the interest and importance attached to a knowledge of its physiology. In the original description of the organism (Waksman and Joffe, 1922) was included a photomicrograph the essential features of which are reproduced from our own cultures in figure 1. We have recently had the opportunity to examine pure cultures of this microorganism in the RCA electron microscope, using distilled water suspensions prepared and micrographed by methods previously described (Umbreit et al. 1941, Marton 1941). These electron micrographs (figures 2 through 6) seem to relate so directly to the original photomicrograph that we have felt that they would be of interest to bacteriologists even though the interpretations we have placed upon the evidence at hand may be modified by future study. We have repeatedly noted the forms found in these micrographs in countless preparations studied in the light microscope by a variety of staining methods. Their observation in the electron microscope illustrates, we believe, the profound effect which the latter instrument will exert upon bacteriology.