196 » PHYSIOLOGY OF THE FUNGI 



partially deficient for this vitamin. The partial deficiency of Sclerotinia 

 camelliae is shown in Fig. 35. Deficiencies for inositol are commonly 

 accompanied by deficiencies for thiamine and biotin. Trichophyton 

 discoides is reported as being totally deficient for inositol, pyridoxine, and 

 thiamine (Robbins et at., 1942). Totally deficient mutants of Neurospora 

 crassa have been developed. Their use in bioassays for inositol was 

 described by Beadle (1944) and by Leonian and Lilly (1945). 



Some filamentous fungi reported to be partially or totally deficient for 

 inositol, with other deficiencies given in parentheses, are as follows: 

 Colletotrichum lindemuthianum (certain strains only), Epichloe typhina 

 (thiamine), Lophodermium pinastri (thiamine, biotin), Melanconium 

 hetulinum (thiamine, biotin), Nematospora gossypii (thiamine, biotin), 

 Sclerotinia camelliae (thiamine, biotin), Trichophyton discoides (thiamine, 

 pyridoxine), Valsa pini (thiamine, biotin). 



The effects of temperature upon the synthesis of inositol by Sclerotinia 

 camelliae and upon the toxicity of high concentrations of inositol at high 

 temperatures were described by Barnett and Lilly (1948) and are illus- 

 trated in Fig. 42. 



Mode of action. The addition of inositol overcame the inhibition of 

 growth of Rhizopus suinus due to excess thiamine (Schopfer and Guilloud, 

 1945). In part, the inhibition was due to an increased production 

 of alcohol (pyruvate ^ acetaldehyde—^ alcohol). Similarly, we have 

 observed in our laboratory the same favorable effect of inositol on growth 

 of certain fungi which are inhibited by the presence of excess thiamine. 



NICOTINIC ACID 



A deficiency for nicotinic acid, or nicotinic acid amide, leads to pellagra 

 in man and blacktongue in dogs. The structural formulas of these com- 

 pounds follow: 



/\^r.f^c^vi /\ 



-CONH2 



Nicotinic acid Nicotinic acid amide 



Nicotinic acid was obtained by the oxidation of nicotine in 1867. Knight 

 (1937) and Mueller (1937o) recognized that nicotinic acid amide was a 

 growth factor for certain bacteria. So far as is known, the amide is the 

 form utilized by organisms. Some microorganisms can convert nicotinic 

 acid into its amide with ease, others with difficulty; still others are unable 

 to use nicotinic acid but require either nicotinic acid amide or a coenzyme 

 containing the amide. 



Fungi deficient for nicotinic acid. Rogosa (1943) tested 114 strains of 

 yeast that ferment lactose and found that all of them required an exoge- 



