152 



THE ACTINOMYCETES, Vol. I 



Oxidation of Steroids and Related Com- 

 pounds 



It has long been recognized that actino- 

 mycetes are capable of decomposing fats 

 (Netchaieva) . Until A'ery recently, it was 

 commonly assumed that the only actino- 

 mycetes capable of oxidizing steroids are 

 fonnd largely among the species of Nocardia. 

 Turfitt, for example, demonstrated by means 

 of enrichment culture methods, that the 

 breakdown of cholesterol and other steroids 

 in soils is carried out primarily by nocardias, 

 especially N. erythropolis. Among the other 

 active species, he listed A^. aquosa, N. glo- 

 berula, N. coeliaca, and N. restricta. 



More recently, however, different strepto- 

 myces {S. griseus, S. fradiae, S. venezuelae, 

 and S. aiircofaciens) were found (Sisler and 

 Zobell, Perlman et at., Hirsch et al., Herzog 

 et al.) capable of oxidizing steroids and lip- 

 ids. Some species oxidized lipids completely 

 to carbon dioxide, without the formation of 

 any intermediate metabolites. 



Washed cells of S. albns are able to con- 

 vert estradiol to estrone (Welsch and Hens- 

 ghem); pregnenolone is converted to proges- 

 terone by S. griseus, and progesterone to 

 hydroxy-progesterone by various actinomy- 

 cetes (Perlman et al.). The conversion of 

 progesterone-(A'*-pregnene-3 ,20-dione) to 

 Ai'^-androstadiene-3,17-dione by Fried et 

 al. suggested that the enzymes which carry 

 out this transformation are adaptive in 

 origin. The metabolism of progesterone by 

 washed *S. lavendulae cells grown in media 

 supplemented with progesterone or in un- 

 supplemented media was inhibited by azide, 

 cyanide, or arsenite but not by selenite or 

 fluoride (Perlman et al. lOo.'S). The conver- 

 sion of progesterone l)y cells grown in un- 

 supplemented media was also inhibited by 

 the addition to the pi'ogesterone-cell-suspen- 

 sion of certain antibiotics, such as strepto- 

 mycin. Addition of any of the antibiotics to 

 the steroid-cell-suspension 12 or more hours 

 after the steroid was mixed with the washed 



cells had no effect on the conversion. The 

 antibiotics had no effect on the progesterone- 

 oxidizing ability of washed cell suspensions 

 of S. lavendulae grown in media supple- 

 mented with progesterone. 



According to Vischer et al., submerged 

 cultures of various streptomyces are able to 

 convert cortexone to 1 Go; -hydroxy cortexone. 



Saburi et al. isolated several streptomyces 

 which utilize cholic acid as the sole source of 

 carbon. The utilization of these acids de- 

 pends on the nuclear constitution and the 

 length of the side chains of the bile acids. S. 

 gelaticus was found capable of converting 

 cholic acid in a C-22 acid (C22H28O4). When 

 S. gelaticus was cultured in a synthetic me- 

 dium containing cholic acid as the sole source 

 of carbon, it oxidized cholic acid to an acid 

 with melting point 280 to 282° (decomposes), 

 which was presumed to be 7a-hydroxy-3, 12- 

 dioxo-A'*-bisnorcholenic acid. When it was 

 grown in a medium containing cholic acid 

 and glucose as the carbon sources, various 

 intermediates such as 7Q:,12a-dihydroxy-3- 

 oxocholanic acid, 7Q:-hydroxy-3,12-dioxo- 

 cholanic acid, 7a-hydroxy-3, 12-dioxo-A''- 

 cholenic acid were formed (Hayakawa et al.). 

 Hayakawa et al. (1958) later demonstrated 

 that S. rubescens possesses an alternate path- 

 way for the degradation of cholic acid from 

 that of *S. gelaticus. 



According to Collingsworth et al., S. 

 fradiae is able to convert ll-desoxy-17-hy- 

 droxycortisone (comp. S) to 17-hydroxy- 

 corticosterone (comp. F). 



Webley and deKock studied the oxj^gen 

 uptake by washed suspensions of Nocardia 

 opaca. The uptake was increased by the 

 presence of n-dodecane, n-tetradecane, n- 

 hexadecane, n-octadecane, and paraffin wax. 

 Decyl, lauryl (dodecyl), and octadecyl alco- 

 hols also ga\'e increascnl oxygen uptake, but 

 amyl, ?',soamyl, ?'.sY>hexyl, and heptyl alcohols 

 were toxic. The long-chain fatty acids (C7- 

 Cir,) were all metabolized at \-ery low con- 

 centrations (0.0012 iM). 



