|Title:||A Preliminary Study of the Fungal Flora of Ethiopian Cereal Grains with Special Emphasis on the Prevalence of Toxicogenic Groups|
|???metadata.dc.contributor.*???:||Dr. Berhanu Abegaz|
|Publisher:||Addis Ababa University|
|Abstract:||Bacteria, moulds and yeasts on surface of cereal seeds (nteff'f, maize, barley and soeghum) were numerated. Bacteria were in general found in greater numbers than moulds or yeasts per gram of grain. Teff harbours a higher number of bacteria (100,000 to 10,000,000 per gram) than the three cereal grains. Mould and yeast counts were not appreciably different - these fungi were found to occur in the range between 10,000 and 1.000,000 /gm of grain. The mycoflora of the four cereal grains was studied, and in the survey 18 genera of fungi were identified, Aspergillus, Penicillium and Fusarium were fpund to be the most prevalent genera. Teff was found to harbour the least number of fungal genera. Fusarium, Trichodevma, Rhizopus and Mucor were not found from any of the teff samples examined, Chaotomium (35%), PenixiJU.ium (35%), Aspergillus (25%), Alternaria (15%) and Helmin^osporium (15%) were the most common genera in teff. Aspergillus a- an (^ Penicillium species were found in all grain types in a range of 25-60%. Fusarium was found to be most associated with maize (62%) and 53or ghu m (30%) Changes in the fungal flora were found to vary with, storage period. Fusariujn (807o), Alterruria (537o) and Chaetomium (53%) were fche mbst prevalent genera in maize and sorghum stored for less than 2 months > Aspergillus (100%), Penicillium (427o) and Rhizopus (42%) were found to be dominant from long-term (greater than 6 months) stored grains. On the other hand, Alternaria, Chaetomium and Helminthbsj^orium were the genera absent from all long-term stored samples. The range 10-14% was the moisture level of most grain samples examined. In general, teff and barley samples contained less moisture than maize and sorghum. The highest moisture content (16-17%) was determined from sorghum samples. Aspergillus flavus was present in 24% of 110 grain samples examined. It was found to be more prevalent in maize (33%) and sorghum (3370). It was found to be more common in grain samples from Jimma (32%) and Dire D.iwa (30%) areas than from Addis Ababa (15%) or Shashemene (1570) samples. The aflatoxin producing ability of 20 isolates of A. was investigated, sixteen isolates (80%) were capable of producing aflatoxin and it was also ‘o found that all cereal grains provide a suitable substratum for aflatbxin production in vitro. Fusarium roseurn was found to betrmost prevalent in maize (357o), rare in barley (5%) and sorghum (7%) while none was isolated from teff. Out of the five Fusarium roseum isolates examined only one showed toxicity by the rabbit skin toxicity test. From other Fusarium spp. Isolates shbwed toxicity out of the seven tested. Ochratoxin was not detected in any of the Aspergillus and Penicillium isolates examined|
|Description:||A Thesis Submitted to the School of Graduate Studies of Addis Ababa University in Partial Fulfillment of the Degree of Master of Science in Biology|
|Appears in Collections:||Thesis - Biology|
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