in(Kiii:.Mic.\i, .\("n\i'ni:s 



157 



oigniiisms (iilT(>r, holli (|U;ilit:i(i\('ly and 

 (luaiit ilat i\"cly, in this connection. l'\'(loro\' 

 and l\ndriasli('\ a (111.").")) I'ound in cnlt nrcs of 

 actinoniycctcs with nitrate as a source of 

 nit ro,ii;en, traces ot' nit rite and hydioxylaniinc^ 

 in far lowci' concentrations than I he amount 

 of niti-ate tliat (hsappc^ared. 'I'hey reached 

 the conchision that the rechiction took place 

 to molecular nitroiien. 'I'he reaction (»f the 

 niechum remained acid, pr(>sumal)ly because 

 of tile format it)n of organic acids from the 

 sugar (Table o.S). 



Nitrogen Fixation 



\'arious reports ha\'e been made in the 

 past of the ability of one or more actino- 

 mycetes to fix atmospheric nitrogen. Fedonn' 

 and Kudriasheva (1950) came to the con- 

 clusion that \arious actinomycetes are capa- 

 ble of fixing atmospheric nitrogen, thus con- 

 firming the claims of Emerson, Carter and 

 Greaves (1928), Kober (1929) and von 

 IMotho (1940). On the other hand, such 

 chums were denied by Beijerinck (1900), 

 Fousek (1912), Miuiter (1916), Waksman 

 (1920), and Krassilnikov (1938). Repeated 

 studies by Waksman (1920), Allison et al. 

 (1984), and Shinobu (1953) failed to confirm 

 the reports. 



Recent evidence .seems to .suggest a nitro- 

 gen-fixing capacity for certain particular 

 species, as reported for .4. spinae by Wlich. 

 Metcalfe and Brown (1957) described two 

 nocardias, A', calcarca and N. cdlulans, iso- 

 lated from grassland lime .soils. These cul- 

 tures were found to ha\-e the capacity to fix 

 atmospheric nitrogen to the extent of 2.0 to 

 4.5 mg of X gm of gluco.se or other carbon 

 source in the medium. The .second culture 

 was also capable of decomposing cellulose, 

 the amount of nitrogen fixed being 5 to 12 

 mg of X/gm of cellulose decomposed. 



Acid Production 



As pointed out pre\'iously, during the 

 growth of actinomycetes in media containing 



Taiimo WA 



luihirlion of iiilidtcs Inj aclinoiiu/rclcH under 



iiiiiii lohic coiKliliom, in a nitrogen alniosphere 



(Fedorov jiiid Kudria.slieva) 



proteins, amino acids, or nitrates as sources 

 of nitrogen, the i-eaclion tends to become 

 alkaline, even in the presence of .sugars as 

 sources of caibon; wheii ammonium salts 

 are present as the sole .sources of nitrogen, 

 the reaction may become acid. Certain acti- 

 nomycetes, howe\er, are capable of forming 

 from carbohydrates \-arious organic acids, 

 depending on the nature and concentration 

 of the carbohydrate. It has been suggested 

 that the Krebs tricarboxylic acid cycle oper- 

 ates in the metabolism of glucose by at least 

 certain species of actinomycetes, as in the 

 case of S. griseus (Inoue) , 



S. lavendulae gives rise to fairly large 

 amounts of lactic acid (Table 34), provided 

 sufficient carbohydrate is present in the me- 

 dium; the pll changes to 5.7 in the presence 

 of 5 per cent gluco.se (some actinomycetes 

 produce enough acid to reduce the pH as 

 low as 4.(3). Lactic acid is not found in any 



Table 34 



Acid formation from glucose by S. lavendulae 



(Woodruff and Foster) 



