132 Perspecfives in Microbiology 



progesterone (XI) is partly reduced to 20p-hydroxy-4- 

 pregnene-3-one (XXXIII) by Streptomyces lavendulae, and 

 work in our laboratories (32) has shown that an actinomy- 

 cete reduces the 20-ketone group of desoxycorticosterone 

 (XVI) to 20a,21-dihydroxy-4-pregnene-3-one (XXXIV). 



CH2R 



t 



HC-ORi 



XI 20^-Hydroxy-4-pregnene-3-one (XXXIII) 



Progesterone (XI) R = H R = - H, OI?: = -OH Streptomyces 



Desoxycorticosterone 20(i-21-Dihydrox>'-4-pregneiie-3-one (XXXIV) 



Pt = 6H ORi~-O.H, R---OH Actinomyccte 



When 3-ketobisnor-4-cholene-22-al (XXXV) is exposed 

 to Rhizopus nigricans, the aldehyde group is reduced to a 

 primary alcohol and an lla-hydroxyl group is also intro- 

 duced (17). The resulting compound is 3-ketobisnor-4- 

 cholene-lla,22-diol (XXXVI). 



CH3 CH3 



H-C-C C-CH2OH 



HO. 



Rhizopus 



Q'^^.^^.^ nigricans ^. 



XXXV XXXVI 



3-Ketobisnor-4-cholene-22-al 3-Ketobisnor-4-cholen5-llcr,22-diol 



Many of the reactions mentioned in this paper are at 

 present extremely difficult to carry out by chemical means, 

 and yet enzymatically these fungi encounter no difficulty 

 in performing the desired reaction. 



Several of these microorganisms have been so well 

 charted in regard to their enzyme systems that not only can 

 they be used for preparative purposes, but also they can 

 be employed to determine chemical structure of certain 

 steroids. For example, when progesterone (XI) is converted 

 to lla-hydroxy-progesterone (XII), a dihydroxyprogester- 

 one (XXXVII) is formed (13) as a by-product, which was 



