190 PHYSIOLOGY OF THE FUNGI 



molecule. Robbins and Kavanagh (1941) showed that P. blakesleeanus 

 destroyed the thiazole more rapidly than it did the pyrimidine moiety. 

 Thus, an excess of thiazole in the mixture of the two moieties was more 

 effective than equal quantities. They termed this the thiazole effect. 



Some thiamine -deficient fungi. A deficiency for thiamine is by far 

 the most common vitamin deficiency among filamentous fungi isolated 

 from nature. Fries (1948) states than over 200 fungi are known to be 

 partially or totally deficient for thiamine. No doubt this is a modest 

 estimate. Deficiency for this vitamin is more common among certain 

 groups of fungi than others. For example, all species of Phytophthora 

 studied have been found to require the intact molecule of thiamine. 

 Only a few species of the true Basidiomycetes have been reported to be 

 self-sufficient for thiamine. Many of these fungi show only partial 

 deficiencies, while some are totally deficient. In most cases, however, 

 there seems to be little or no correlation between thiamine deficiency and 

 taxonomic relationship. 



Some common filamentous fungi (other than Basidiomycetes) which 

 have been reported to be totally or partially deficient for thiamine or its 

 moieties, with other deficiencies (if any) indicated in parentheses, are 

 as follows : Blakeslea trispora, Ceratostomella fimbriata, C. ips (biotin and 

 pyridoxine), C. montium (biotin and pyridoxine), C. pini (biotin), Chae- 

 tomium convolutum (biotin), Choanephora cucurbitarum, Coemansia inter- 

 rupta (biotin), Dendrophoma obscurans, Endothia parasitica (biotin), 

 Hypoxylon pruinatum (biotin), Lambertella pruni (biotin), Lophodermium 

 pinastri (biotin and inositol), Melanconium betulinum (biotin and inositol), 

 Melanospora destruens (biotin), Mucor ramaymianus, Nectria coccinia, 

 Ophiobolus graminis (biotin), Phycomyces blakesleeanus, Phytophthora 

 spp., Piricularia oryzae (biotin), Pleurage curvicolla (biotin), Podospora 

 curvida (biotin), Pythiomorpha gonapody aides, Pythium arrhenomanes , P. 

 ascophallon, P. butleri, P. oligandrum, Sclerotinia camelliae (biotin and 

 inositol), S. minor, Sordaria fimicola, certain isolates only (biotin), 

 Thielaviopsis basicola, Valsa pini (biotin and inositol), and Xylaria 

 hypoxylon. 



Reports of deficiencies for most of the above-named fungi may be found 

 in the references for this chapter. Some few of these fungi have been 

 studied in our laboratory and have not been previously reported as being 

 deficient for thiamine. For thiamine-deficient yeasts see the reports of 

 Burkholder (1943) and Burkholder et al. (1944). 



Mode of action. One of the primary uses of thiamine in plants and 

 animals is for the regulation of carbohydrate metabolism. It is also 

 probable that thiamine may be involved in other processes. A vitamin 

 which constitutes a part of an enzyme system is known as a coenzyme. 

 Generally a vitamin must be combined with organic or inorganic com- 



