Oct. 22, I92I Flora of Corn Meal 187 



flavus show that very little development of this species occurs below 16 

 per cent, but that from 16 per cent upward development of this species 

 rapidly increases and the number of forms capable of growing rapidly 

 rises. Among the characteristic saprophytic molds observed under 

 these conditions, in about the order of their abundance under the con- 

 ditions, are Aspergillus repens, Aspergillus flavus, Actinomyces sp., 

 Penicillium sp. and Citromyces sp., Fusarium sp., Aspergillus candidus, 

 Aspergillus ochraceous Wilhelm, Aspergillus iamari, and Aspergillus niger. 



Bacterial activity appears to be a concomitant of the disintegration 

 due to mold action in such rotting processes as this. As indicated by 

 Bailey and Thom (2, Table I), active disintegration by molds is 

 accompanied by an increase in the water percentage of the sample. 

 Bacteria follow rather than initiate the process in the samples studied, 

 thus becoming a small factor in the merchantable product. 



Throughout this investigation a close correspondence has been observed 



between the flora of deterioration in unground com and the flora of the 



milled product. 



SUMMARY 



In seeking possible causes for the well-recognized instability of com 

 meal, cultures show considerable numbers of molds and bacteria to be 

 generally present. Among these the following species of molds were 

 characteristic of many series of cultures: Fusarium sp., Aspergillus 

 repens, A . flavus, A . tamari, A . niger, Citromyces (or Penicillium section 

 Citromyces) sp., Penicillium oxalicum, P. luteum varieties, Mucor sp., 

 Rhizopus nigricans, and Syncephalastrum sp., together with various 

 yeasts and yeast-like fungi. Among bacterial groups, the colon- aerogenes 

 group and lacto-bacilli were most abundant in fresh meal. Aerobic 

 spore formers and micrococci were always present and persisted in the 

 stored product. 



Within the range of composition found in merchantable meals, no 

 bacterial activity was detected. Only one grade of unbolted meal 

 showed signs of mold development below 13 per cent of moistiu-e. Above 

 13 per cent moisture, Aspergillus repens begins to be an active agent 

 of spoilage somewhere between 13 and 15 per cent of moisture, varying 

 with the form of milling practiced. Several other species of molds are 

 active in meal containing 16 per cent moisture; and numerous forms, 

 including some bacteria, develop when 18 to 20 per cent of moisture is 

 found. 



Many samples of corn are found to carry extensive infections with 

 Fusarium, Diplodia, Aspergillus repens, or Penicillium, especially in the 

 germinal area and in the tip of the kernel. These sections of the kernel 

 are removed in varying degrees by different milling systems. The 

 bolted meals examined show a corresponding reduction in count of 

 viable organisms as shown by culture. 



