Effect of a non-methanogenic symbiont and exogenous stigmasterol on the viability and tetrahymanol content of the anaerobic ciliate Trimyema compressum.

The effect of a non-methanogenic symbiont on the viability of Trimyema compressum strain N, cultivated monoxenically on a Bacteroides strain, was studied by elimination of the symbiont. Aposymbiotic cells and symbiont-bearing cells reached identical yield in short term experiments. After some weeks aposymbiotic cells had lost the ability to divide and exogenous stigmasterol was necessary for growth as observed for T. compressum strain K. Though with lower yields, some hopanoids were able to replace stigmasterol. The effect of stigmasterol on the generation time of T. compressum strain N and persistency of the non-methanogenic symbiont was studied. Both, higher temperature and stigmasterol supply, stimulated growth of the ciliate but, beside treatment with penicillin, only stigmasterol resulted in a loss of the non-methanogenic symbiont by statistical outgrowth. Triterpenoids were extracted from T. compressum strain N and from T. compressum strain K cultivated with optimal and suboptimal stigmasterol supply. Symbiont-bearing cells of T. compressum strain N and symbiont-free cells of T. compressum strain K grown under conditions of suboptimal stigmasterol supply contained tetrahymanol. The amount of tetrahymanol extracted per mg protein of the ciliate biomass indicated that biosynthesis of tetrahymanol in T. compressum is inhibited by exogenous stigmasterol. Tetrahymanol is not a product of the symbiont's metabolism. Stigmasterol has an effect on growth of the ciliate which appears to be similar to that of the non-methanogenic symbiont.

Prokaryotic triterpenoids: O-alpha-D-glucuronopyranosyl bacteriohopanetetrol, a novel hopanoid from the bacterium Rhodospirillum rubrum.

A novel hopanoid bearing a glucuronopyranosyl residue linked via an alpha-glycosidic bond to the hydroxyl group of C-35 in bacteriohopanetetrol was isolated, from the type strain of Rhodospirillum rubrum as well as from a mutant lacking blue carotenoid.

The hopanoids of the purple non-sulfur bacteria Rhodopseudomonas palustris and Rhodopseudomonas acidophila and the absolute configuration of bacteriohopanetetrol.

Five complex hopanoids have been detected in the purple non-sulfur bacterium Rhodopseudomonas acidophila. Next to the polyfunctionalized methylcyclopentane bacteriohopanetetrol ether already isolated from Methylobacterium organophilum, 35-carbamoylbacteriohopane-32,33,34-triol, 34,35-dicarbamoylbacteriohopane-32,33-diol and two nucleoside analogues, (22R)-30-(5'-adenosyl)hopane and (22S)-30-(5'-adenosyl)hopane were isolated and identified by spectroscopic and chemical methods. In Rhodopseudomonas palustris, however, only 35-amino-bacteriohopane-32,33,34-triol was detected. Chemical correlation between adenosylhopane and bacteriohopanetetrol, as well as comparison of derivatives obtained from bacterial and synthetic hopanoids, permitted the determination of the configurations of all asymmetric centres of the side-chain of bacteriohopanetetrol as 22R, 32R, 33R and 34S. According to the stereochemistry, this side-chain could be a D-ribose derivative linked through its C-5 carbon atom to the hopane skeleton.

Novel hopanoids from the methylotrophic bacteria Methylococcus capsulatus and Methylomonas methanica. (22S)-35-aminobacteriohopane-30,31,32,33,34-pentol and (22S)-35-amino-3 beta-methylbacteriohopane-30,31,32,33,34-pentol.

The major hopanoid of the methylotrophic bacteria Methylococcus capsulatus and Methylomonas methanica was identified by spectroscopic methods as (22S)-35-aminobacteriohopane-30,31,32,33,34-pentol. Minor companions were, in both bacteria, 35-aminobacteriohopane-31,32,33,34-tetrol and in Methylomonas methanica, 35-aminobacteriohopane-32,33,34-triol. In Methylococcus capsulatus the aminopentol and the aminotetrol were accompanied by their homologues possessing an extra methyl group at C-3. Bacterial hopanoids with a functionalized C-30 carbon atom such as these two new aminopentols are possible precursors of widespread C29 hopanoid chemical fossils.

A novel hopanoid, 30-(5'-adenosyl)hopane, from the purple non-sulphur bacterium Rhodopseudomonas acidophila, with possible DNA interactions.

A novel hopanoid, 30-(5'-adenosyl)hopane, was isolated from the purple non-sulphur bacterium Rhodopseudomonas acidophila and identified. The significance of this triterpenoid in terms of bacteriohopanepolyol biosynthesis, membrane reinforcement and possible interactions with nucleic acids is discussed.

Prokaryotic triterpenoids. The hopanoids of the purple non-sulphur bacterium Rhodomicrobium vannielii: an aminotriol and its aminoacyl derivatives, N-tryptophanyl and N-ornithinyl aminotriol.

Triterpenoids belonging to the hopane family are widely distributed in prokaryotes. Three new hopanoids have now been isolated from the purple non-sulphur bacterium Rhodomicrobium vannielii and identified essentially by spectroscopic methods. The basic compound is the 35-aminobacteriohopane-32,33,34-triol, from which the other two hopanoids are derived by introduction of a tryptophanyl or an ornithinyl moiety linked to the amino group at C-35 via an amide linkage. This is the first report of hopanoids possessing an amino group in their side-chain and linked to aminoacyl residues.