PHYSIOLOGICAL, BIOCHEMICAL, AND ULTRASTRUCTURAL CHARACTERS OF SOME STRAINS OF VIRIDIELLA-FRIDERICIANA (CHLOROPHYTA, CHLOROCOCCALES)

According to the ultrastructural, biochemical and physiological characters, three Chlorella-like strains, isolated from extremely low pH environments in Italy, were assigned to the species Viridiella fridericiana. The characters used were: absence of sporopollenin in the cell wall and of a pyrenoid in the chloroplast; hydrogenase activity, formation of secondary carotenoids under nitrogen deficiency, liquefation of gelatin, hydrolysis of starch; ability to grow on nitrate or ammonium containing media, thiamine requirement, acid-tolerance, salt-tolerance, termophily. The features considered, if compared to those of the type strain, did not reveal significant differences among the strains of V. fridericiana.