TRANSFORMATION OF ROD-SHAPED ALGAL CELLS INTO SPHERICAL CELLS

Transformation of the rod-shaped algal cells, which before the conversion could be considered as belonging to the genus Stichococcus, into spherical cells was achieved by the action of the tryptic soy broth and some other organic media. Transformation did not involve degradation of the cell wall, and the resulting spheres were not sensitive to osmotic shock. The transformed cells could be propagated as spheres for several months but eventually reverted to the original rod shape. The reversion could be hastened by transferring spherical cells back into inorganic medium and growing the cells autotrophically. For a long time after reversion, the cells maintained characteristics different from those of the original rod-shaped cells which did not go through the conversion and reversion processes. The reverted cells had a higher rate of heterotrophic growth, a lower rate of autotrophic growth, and a lower capacity for being again transformed into spheres under the influence of tryptic soy broth.