Formation, growth and regeneration of incomplete cell wall in spheroplasts of the blue‐green alga Anacystis nidulans in liquid media

Growing cells of blue‐green alga, Anacystis nidulans, were treated with lysozyme in osmotically stabilized nutrient medium. Their development and regeneration ability was studied in liquid media. During 5–8 hrs about 95% of cells were converted to osmotically sensitive spheroplasts having a residual wall layer on their surface. The highest viability of spheroplast population was achieved using egg‐white lysozyme for spheroplast preparation and gradual dilution by nutrient medium instead of centrifugation for lysozyme removal. Most of such prepared spheroplasts survived for 3 days of cultivation in nutrient medium, and started to die gradually from 3 to 10 days. Spheroplasts were growing spherically, about 30% of them were growing for 8 days up to 40‐fold increase in volume. Multiplication of thylakoid cisternae in growing spheroplasts was proved by freezeetching. Electron microscopy further revealed newly synthesized amorphous walls of isodiametrical appearance by growing spheroplasts resembling the original cell walls of cells. In liquid media blue‐green alga spheroplasts of Anacystis nidulans can grow for a number of days, however, only regeneration of incomplete wall occur unable to promote reversion of spheroplasts to cells.