A Comparison of the Oxidative Metabolism of Light and Dark Grown Rhodospirillum Rubrum

Abstract

Using a manometric or a dehydrogenase assay, activity for most of the interrnecli;~tcs of the tricarbosylic acid cycle \\;as demonstrated in extracts from Rl~odospirillrinz r~rbrz~nz grown photosynthetically (anaerobic light), heterotrophically (aerobic dark), or a combination of both (aerobic light). Dehydrogenases for succinate and a-ketoglutarate \\.ere nlore active in extracts from cells grown photosynthetically. Extracts from cells grown heterotrophically had the greatest oxidative activity. Succinic dehydrogenase was associatecl with larger macro~nolecular units in all extracts \\:bile the other dehydrogenases behaved as soluble enzymes. Conditions of cultivation affected the rate a t which Iceto acids \\ere formed from citrate. Rlzodopsez~dotno~zc~s palz~stris also possessetl tricarboxylic acicl dehydrogenases whether grown photosynthetically or heterotrophically.Can. J. Microbiol. Downloaded from www.nrcresearchpress.com by Calif Dig Lib -Berkeley on 11/21/14For personal use only.