9 



Terpenoids and Steroids 



Ergosterol is the principal fungal sterol. It was named for its 

 occurrence in ergot, and it has been isolated from a wide variety 

 of other fungi as well as from lichens. It has been reported to 

 be the only sterol in certain molds, ^ but it is often accompanied 

 by related compounds. It has been identified also in algae. 

 Some yeasts produce several per cent of their dry cell weight in 

 ergosterol. Yeasts which produce large quantities of fat do not 

 necessarily produce a higher proportion of ergosterol. 



There have been few reports of the isolation or detection of 

 sterols in bacteria, and there is doubt as to whether bacteria 

 produce sterols. A critical historical review of this question has 

 been published.- Mevalonic acid is an acetate-replacing factor 

 in lactobacilli, and a labeling study ■ with paper chromatography 

 and spectral work on the labeled non-saponifiable lipides showed 

 the presence of non-steroid, hydroxylated and unsaturated com- 

 pounds with more than 15 carbon atoms. It may be that sim- 

 pler substances of this sort replace sterols in bacteria. An 

 artificial requirement for vitamin D2 can be induced in some 

 bacteria. The resulting inhibition of growth can be reversed by 

 vitamins D2, D., or suprasterol, but not by 7-dehydroergosterol 

 nor by cholesterol.'^ 



Yeasts and higher fungi produce squalene and Co- to C;^! com- 

 pounds, some of which have been shown to be precursors of 

 cholesterol in mammalian metabolism. Some higher fungi and 

 many lichens produce triterpenes or close derivatives. 



Since the availability of isotopes, which permit the tracing of 

 small quantities of material, much of the biosynthetic route to 



Joseph V. Fiore, Arch. Biochem. 16 161 (1948). 

 2 Audrey Fiertel and Harold P. Klein, J. Bacteriol. 78 738 (1959). 

 •'* E. Kodicek, Abstracts of the Gordon Conference on Vitamins and 

 Metabolism, 1958. 



