Spheroplasts were prepared, under the action of lysozyme (200 and 400 mcg/ml) from the cells of Thiobacillus ferrooxidans grown on the Waksman medium with elementary sulfur after their treatment with 0.5M NaCl solutions and exact exposure to sucrose (0.5M). Intracellular structures were revealed on the spheroplasts which could not be detected on intact cells.