When acted upon by streptomycin, certain strains of E. gracilis undergo a permanent loss of chlorophyll, without being inhibited in growth if good energy and carbon sources are supplied to make up for the loss of photosynthesis. The degree of bleaching is proportional to the degree of exposure to streptomycin. Proliferating and non-proliferating cells, and cells exposed in the light and in the dark, appear equally susceptible to bleaching.