the spherical cells of "sulfurisphaera ohwakuensis" are 1.2–1.5 µm in diameter. thin sections of the organism reveal an envelope (approx. 24 nm) surrounding the cell membrane. it grows organotrophically on proteinaceous, complex substrates such as yeast extract, peptone, and tryptone. growth was not observed on single sugars or amino acids such as d-glucose, d-galactose, d-fructose, d-xylose, lactose, maltose, sucrose, alanine, glutamate, glycine, and histidine.