188 



THE ACTIXOMYCETES, Vol. I 



terns, reported that the anaerobic pathogenic 

 forms, or species of Actinomyces, differ from 

 the aerobic forms in that they form such 

 enzymes in mere traces, if at all. No attempt 

 has been made to study these enzyme sys- 

 tems in detail or to utilize them for any 

 practical purposes. 



Polysaccharidases 



Various actinomycetes are capable of uti- 

 lizing agar and other polyuronides as sources 

 of energy. The agar is thereby liciuefied. 

 This is true particularly of such forms as 

 S. coclicolor (Stanier). 



A detailed study of the enzymes in\olved 

 in the decomposition of seaweeds and sea- 

 weed products (laminarin and alginates) b}^ 

 actinomycetes has been made by Chesters 

 et al. (1956). Various nocardias (V. citrea) 

 have been found to be active in l)reaking 

 down calcium alginate and laminarin. Cer- 

 tain streptomycetes were particularly active 

 in decomposing laminarin. In this respect, 

 they were much more active than bacteria. 

 The enzymes laminarinase and alginase wei'e 

 isolated from cultures of these organisms 

 and found to be highly active upon the 

 corresponding substrates, as well as upon 

 starch and calcium pectate. These enzymes 

 were obtained either from the culture fil- 

 trates of the organisms or by treating the 

 mycelium with 15 per cent ethyl alcohol. 



Sorensen (1957) found that both *S. alhus 

 and M. chalcea, when grown in a xylan- 

 containing medium, have the capacity to 

 produce the enzyme xylanase. This enzyme 

 is extracellular and can attack the xylan 

 chain at random along its length, yielding a 

 mixture of shorter or longer chain fragments. 

 These saccharides, of which xylotriose is the 

 shortest, are attacked further by xylanase, 

 giving the following end products: xylose, 

 arabinose, xylobiose, and uronic acid or 

 uronic acid-xylose oligosaccharides. The xy- 

 lanase produced by the streptomyces con- 

 tained two fi'actions, of which one trax'eled 



toward the anode and the other remained 

 at the starting point. The two fractions 

 were found to represent two proteins with 

 identical enzymatic functions. 



Invertase 



Invertase is widely produced by actino- 

 mycetes, as shown by Caminiti, Krainsky, 

 and Waksman. Lieske was unable to demon- 

 strate the production of this enzyme l)y the 

 cultures he investigated, but he did not deny 

 such capacity. The formation of in\'ertase 

 and other saccharidases by actinomycetes 

 has also been studied by Hofmann and 

 Latzko (1950). 



The ability of some actinomycetes to uti- 

 lize sucrose as a source of carbon is largely 

 dependent upon the property of the organ- 

 isms to produce invertase. This capacity has 

 not been established for all organisms, how- 

 ever. Krassilnikov says that nocardias are 

 able to utilize sucrose without prior in\'er- 

 sion. According to Waksman, only those 

 forms that are able to produce invertase 

 make abundant growth on media containing 

 sucrose. 



In view of the constancy of this pr(jperty, 

 it has been suggested that invertase produc- 

 tion be utilized for species differentiation. 



Cellulolytic Enzymes 



Although the property of decomposing 

 cellulose is widely distributed among micro- 

 organisms, neither the cellulolytic mechan- 

 isms nor the cellulases involved in the proc- 

 esses of decomposition are well understood. 

 As shown previously, many actinomycetes, 

 especially streptomyces, are able to grow 

 on cellulose as the only source of carbon. 

 This was established through the work of 

 Fousek, Krainsky, Waksman, and others. 

 Various actinomycetes capable of decom- 

 posing cellulose ha\'e been described under 

 different names, such as Mycococcus cytopha- 

 gus of Bokor, Micrococcus cylopkagxs of 

 Merker, and the organism described by 



