Chapter V —87— Metabolism 



ber of actinomycetes (460). Jensen (185) isolated from a forest soil 

 an actinomyces which even had a definite preference for an acid reac- 

 tion; hence, he named it S. acidofhilns. 



The fact that various actinomvcetes are able to produce organic acids 

 form carbohydrates has been long recognized (470). Magnus (281) 

 obser\'ed that many of the actinomycetes found in the larynx are able 

 to produce acid of the lactic t)npe (ether-soluble) even in sugar-free 

 media. Plotho (341) confirmed these observations and definitely 

 established the fact that the acid produced by various actinomycetes is 

 of the lactic type, as shown in Table 13. 



Woodruff and Foster (517) established that S. lavendulae is also 

 capable of producing considerable amounts of lactic acid from carbo- 

 hydrates. The nature of the nitrogen source is of considerable impor- 

 tance in this connection, as shown in Table 13. In the presence of 



Table 14: Acid formation frofn glucose hi aerated cultures of S. lavendulae (517): — 



♦ Initial ?H was 7.2. 



glycine, for example, much more sugar was consumed but less lactic acid 

 produced than with tryptone as a source of nitrogen. This is particu- 

 larly true for submerged cultures. In the absence of glucose or with 

 only extremely low concentrations of sugar and in the presence of tryp- 

 tone, ammonia will accumulate in the medium, gradually making it 

 alkaline. In the presence of 1 per cent glucose, however, the pH is 

 lowered appreciably even in buffered media, due to the formation of 

 organic acids. In the presence of 2 per cent glucose, especially in un- 

 buffered media the fW levels may go down as low as 3.2 in 2 days. The 

 changes in reaction are thus parallel to the concentrations of sugar 

 (Table 14). 



On the basis of the sugar consumed, lactic acid production was 

 found to be equivalent to 25.8 and 7.5 per cent in tr)'ptone and glycine 

 media, respectively. This high conversion took place under conditions 

 of forced aeration. Other actinomycetes, especially S. griseus, also pro- 

 duce lactic acid (395). This was found to hold true particularly for 

 the degenerated strains which have lost the capacity to form aerial my- 

 celium. 



In addition to lactic acid, S. lavendulae produces a certain amount 



