VITAMINS 



189 



Table 33. Assay for Thiamine and Thiamine Moieties in Mycelium and 

 Medium Extracts of Some Fungi after Growth on Media Containing 



THE Minimum Growth-factor Requirements 

 Numbers refer to relative growth on the scale of 10. (Leonian and Lilly, Plant 

 Physiol. 15, 1940.) 



* Upper figures refer to extract of mycelium, lower figures to extract of medium. 



It is evident that Fusarium niveum was able to synthesize thiamine 

 from the basal medium because two test fungi which require thiamine 

 per se grew on extracts prepared from the hyphae. The same type of 

 proof shows that Pythiomorpha gonapodyoides synthesized thiamine when 

 thiamine pyrimidine was added to the basal medium. Mucor raman- 

 nianus synthesized thiamine when thiamine thiazole was added, and 

 Phycomyces blakesleeanus synthesized thiamine when both moieties were 

 added. 



In all cases the greater portion of thiamine was stored within the 

 mycelium, and only small amounts were present in the medium. The 

 medium extract from three fungi contained no thiamine, although appre- 

 ciable quantities of the pyrimidine and thiazole moieties were present 

 in all media. This shows that Phytophthora erythroseptica, for example, 

 had broken down the thiamine molecule into its moieties, which diffused 

 into the medium and were later utilized by certain fungi, such as Phyco- 

 myces blakesleeanus. This suggests that in the process of its utilization 

 thiamine is slowly destroyed. The moieties may be recombined by 

 certain organisms but not by those which require the entire thiamine 



