A non-extractable triterpenoid of the hopane series inAcetobacter xylinum

Cells of the bacterium Acetobacter xylinum were analysed for their residual triterpenoid content after exhaustive lipid extraction using chloroform/methanol. Whereas the well known bacteriohopanetetrol mixture was present in the extract, the cells still contained a single bacteriohopanepentol cyclitol ether which could be detected either as the primary alcohol derivative after H5IO6 oxidation followed by NaBH4 reduction of the already extracted cells or as the octa-acetate by direct acetylation followed by solvent extraction. This is the first evidence of a probable selective complexation of a hopanoid via non-covalent linkages to other cell constituents.