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Articles by M. A. Hefnawy
Total Records ( 3 ) for M. A. Hefnawy
  M. A. Hefnawy , M. M. Gharieb and A. A. Abou-Seda
  The respiratory activities of osmotolerant fungus Aspergillus candidus were studied to evaluate its response to high osmotic stress. The rate of respiration by the whole cells and mitochondrial fractions increased with elevated sucrose concentrations in the growth medium. The activity of respiratory enzymes such as, succinate dehydrogenase, NADH dehydrogenase, cytochrome oxidase, NADH oxidase and succinoxidase was higher in the cells grown in the presence of high sucrose concentrations, ranging from 1.2 -2.1 times higher than the control. Whereas, NADH dehydrogenase exhibited the highest increase at 50 and 80% sucrose, it increased 6 and 13 times respectively higher than in the control. Electron microscopic observations of A. candidus grown at high osmotic stress revealed a larger size of mitochondria than in the control grown cells. The mean mitochondrial diameter at 50 and 80% sucrose was approximately 2 fold larger than in the control cells grown at 3% sucrose.
  M. A. Hefnawy , M. El-Said , M. Hussein and Maisa, A. Amin
   Seven fungal species were isolated from two uranium ores in Alloga region, west central Sinai, Egypt. They were identified as, Aspergillus flavus, Penicillium brevicompactum, P. oxalicum, P. purpurescens, P. lividum, Aspergillus terreus and P. spinulosum. They were tested for bioleaching activity of uranium from its ores, A. terrus and P. spinulosum showed a high leaching activity. The growth of these fungi highly affected by the presence of the ore in the growth media. The amount of uranium solubilized by A. terreus and P. spinulosum was increased with increasing ore concentrations in the growth media, reaching its maximum at 4%(w/v). Whereas, the highest percentage of uranium released by both fungi was obtained at 1%(w/v), at this concentration the released uranium being 75 and 81.5% respectively for ore (OS1) and 72.8 and 77.6% respectively for the second ore (OS2). The best leaching occurs when the final pH shifts toward acidity. The biosorption of released uranium by the fungal mycelium was also increased with increasing ore concentrations in the growth media. One gram dry mycelium of A. terreus and P. spinulosum could bind approximately 9.6 and 14.2% respectively, at 1% of OS1 and 10.8 and 17% respectively, at the same concentration of OS2 from the total uranium solubilized during bioleaching process.
  M. A. Metwally and M. A. Hefnawy
  The growth of Aspergillus ochraceus was decreased with increasing NaCl concentration. The decreasing ratio of ochratoxin A by NaCl ranged from 25 to 74% at 5 and 15% NaCl respectively. The total soluble protein increased to 37% at 15% NaCl. The total lipids decreased only at 15% NaCl. The myristic and palmitic acids represented the highest concentrations of saturated fatty acids while their concentrations decreased with increasing NaCl. Whereas, 10% NaCl increased the concentrations of the unsaturated fatty acids (oleic and linoleic) and decreased palmitoleic acid. On the other hand 15% NaCl increased linolenic and decreased palmitoleic and oleic acid concentrations. Most of the detected phospholipids increased with increasing NaCl concentrations in the growth medium up to 10%, whereas they decreased at 15% NaCl. Phosphatidyl glycerol, phosphatidyl ethanolamine and phosphatidic acid were the major phospholipids.The genomic DNA of the control and the five NaCl treated samples showed a common band at higher molecular weight.
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