Effect of Aminotriazole and Streptomycin on Multiplication and Pigment Production of Photosynthetic Microorganisms*

Abstract

SYNOPSIS. 3‐Amino‐l,2,4‐triazole (AT) stops multiplication of the photosynthetic protists, Ochromonas danica, O. mal‐hamensis, Euglena gracilis var. bacillaris. and Rhodopseudo‐monas palustris ; it also stops growth of the multicellular plant, Spirodela oligorhiza. O. danica and S. oligorhiza are the most sensitive. AT is about equally inhibitory to algal flagellates grown in the light or dark. Porphyrin biosynthesis is suggested as the probable site of inhibition by AT. Both AT and streptomycin (SM) bleach all the above organisms. Bleaching is permanent only in SM‐bleached E. gracilis ; all the other organisms become fully pigmented when placed in inhibitor‐free media. The uniqueness of the SM‐bkaching of E. gracilis is discussed.