Considerable work has been reported in the last few years on factors affecting the sporulation and germination of bacterial endospores, but there is a marked paucity of literature on the metabolic activity of the resting spore. This is undoubtedly the result of a rather general assumption that these forms represent a dormant stage exhibiting little, if any, metabolic activity and possessing no functional enzymes. There have been previous reports that show that this assumption is not valid. Ruehl (1923) found a gelatinase activity in some instances. Tarr (1933), following the lead of Cook (1932), was able to definitely demonstrate an active glucose dehydrogenase in the spores of several members of the family
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.
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