Prokaryotic triterpenoids: New hopanoids from the nitrogen-fixing bacteria Azotobacter vinelandii, Beijerinckia indica and Beijerinckia mobilis

Three nitrogen-fixing bacteria, Azotobacter vinelandii, Beijerinckia indica and Beijerinckia mobilis, were shown to contain large amounts of triterpenoids of the hopane series. In A. vinelandii, the major compound was a novel bacteriohopanepentol ether accompanied by a similar bacteriohopanetetrol derivative: in both compounds, the hopanoids are linked via an ether bond to a carbapseudopentose moiety often found in bacterial hopanoids. In the two Beijerinckia species, diplopterol and 2β-methyldiplopterol were accumulated in much larger amounts than those usually recorded in hopanoid-producing eubacteria, while 2β-methyldiploptene was isolated for the first time from B. mobilis. Whereas in B. mobilis aminobacteriohopanetriol was the only C₃₅ hopanoid, the simultaneous presence of bacteriohopanetetrol and aminobacteriohopanetriol in B. indica is a rather unusual feature.