BIOLOGICAL CHLORINATION 



7. BIOLOGICAL CHLORINATION 



183 



Chloride ion is commonly present in culture media simply as an 

 accompaniment of essential ions. With the discovery of geodin and 

 erdin in Aspergillus terreus (433, 434), it was realized that chlorine 

 may be incorporated into organic compounds by fungi. Subsequent 

 investigations have shown many chlorinated metabolites; a partial list 

 includes: 



1. p-Methoxy-tetrachlorophenol of Drosophila subatrata (8). 



2. Chlorinated depsidones, e.g., nidulin (Table 4). Chlorinated 

 depsidones are also known in the lichens (24); they are presumably 

 synthesized by the fungus component. 



3. Griseofulvin, a complex benzenoid compound of uncertain struc- 

 ture, produced by Penicillium spp. (96, 256, 411). 



4. Chlortetracycline (aureomycin), an antibiotic of Streptomyces 

 aureofaciens (487). 



5. Chloramphenicol (Chloromycetin) (Table 4). Here the chlorine 

 is attached to a side chain carbon; chloramphenicol is also unusual in 

 its nitrobenzene structure. 



6. Nalgiolaxin, a chlorinated anthraquinone of Penicillium nal- 

 giovensis, occurring in association with its dechloro analogue nalgio- 

 vensin (436). 



7. Caldariomycin of Caldariomyces fumago (Fumago vagans), prob- 

 ably a cyclopentane with two chlorine atoms attached to a ring carbon 

 (141). Terrein, of Aspergillus terreus, not a chlorine compound, is the 

 only other cyclopentane derivative known in fungi (32, 255). 



In a survey of 139 fungi, it was found that strains of Absidia spinosa, 

 Alternaria tenuis, Aspergillus spp., Caldariomyces fumago, Penicillium 

 spp., Syncephalastrum racemosum, and Trichoderma viride incor- 

 porate 15 per cent or more of the available chlorine into organic 

 combinations (141). 



Frequently a compound and its dechloro derivative occur together 

 in one organism, e.g., griseofulvin and dechlorogriseofulvin in Penicil- 

 lium spp. (362). The antibiotics tetracycline and chlortetracycline are 

 produced by different species of Streptomyces, the related oxytetracy- 

 cline by a third (61). The substitution of bromide for chloride in 

 the medium has specific effects of two kinds: either the organism forms 

 the bromo analogue of a chlorine compound (363), or chlorination is 

 suppressed and the dechloro derivative is formed (468). The incorpo- 

 ration of chlorine into tetracycline is also suppressed by copper-corn- 



