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Articles by Hamad Ashraf
Total Records ( 6 ) for Hamad Ashraf
  Ikram-ul-Haq , Shahida Javed and Hamad Ashraf
  The parental strain of Aspergillus niger was subjected to UV irradiations for 5-30 minutes. One hundred and ten mutants of Aspergillus niger were isolated by observing the hydrolysis of starch in the petri plates. Of all the mutants tested, the mutant strain of Aspergillus niger GCBU-25, isolated after 25 minutes of UV irradiation gave the maximum production of AMG (136.1 IU/ml/min), which gave two fold increase in the production of the enzyme than the parental strain. The production of amyloglucosidase reached its maximum (183 IU/ml/min) when starch at 1% level and (NH4)2SO4 at 0.2% level of nitrogen was used as carbon and nitrogen source respectively.
  Sikander Ali , Hamad Ashraf and Ikram-ul-Haq
  Citric acid fermentation by Aspergillus niger GCB-47 was carried out in a 15L stainless stirred fermentor. Among the alcohols tested as stimulating agents, 1.0% methanol was found to give maximum amount of anhydrous citric acid (76.02 g/l), 24 hours after inoculation. This yield of citric acid is 1.76 fold higher than the control. The sugar consumed and %age of citric acid on the basis of sugar used were 108 g/l and 70.39 %, respectively. The mycelia were small round pellets having dry cell mass 14.5 g/l. Addition of ethanol, however, did not found to enhance citric acid production, significantly.
  Ikram-ul-Haq , Shafia Rani , Hamad Ashraf and M. A. Qadeer
  The present study is concerned with the selection of hyper-producer strain of Bacillus subtilis and optimization of the cultural conditions for the production of alpha amylase in shake flask. The UV irradiated strain of Bacillus subtilis was treated with NTG for different intervals of time (5-60 min). One hundred mutant strains were isolated and tested for the production of alpha amylase and Bacillus subtilis GCBCM-25 gave maximum production of enzyme (2210 U/ml). The optimum conditions for the production of alpha amylase were, NaNO3 as nitrogen source, pH 7.5, phosphate buffer as diluent and 4mM CaCl2. The treatment of NTG for 25 min was found to be suitable for the production of best mutant of Bacillus. The production of alpha amylase was significantly increased with the addition of NaNO3 and 4 mM CaCl2 to the fermentation medium.
  Roheena Abdullah , Hamad Ashraf and Ikram- ul- Haq
  The present study is concerned with the selection of carbon sources for the production of alpha amylase by Saccharomyces cerevisiae GCB-20. The lactose, glucose, maltose, xylose and sucrose as carbon sources were tested for the production of enzyme. Of all the sources tested, sucrose at the level of 0.5%was found to be best for the production of alpha amylase (530U/ml/min). The kinetic analysis indicated that the volumetric production of biomass and alpha amylase was significantly higher in the presence of sucrose (0.5%) added to the fermentation medium.
  Hamad Ashraf , Kokub Rana , Hifzah Zainab and Ikram-ul-Haq
  The production of alpha amylase was carried out by thermophilic strains of Bacillus licheniformis. The isolated cultures were screened by solid-state fermentation using wheat bran as substrate, moistened with phosphate buffer (pH 7.5). The culture GHB8 that gave the maximum production of alpha amylase (1277 U/g/min) was used for further studies. The maximum production of alpha amylase (1630 U/g/min) was reached when wheat bran was partially replaced with cottonseed meal in the ratio of 3:1 along with 1 per cent starch. The incubation temperature 40oC was found to be optimum for the production of alpha amylase. The enzyme was most active between 60-70?C.
  Koukab Rana , Ikram-ul-Haq and Hamad Ashraf
  The present study is concerned with the production of amyloglucosidase by UV irradiated strain of Aspergillus niger. The parental strain of Aspergillus niger was subjected to UV irriaditions for 5-30 minutes. One hundred and ten mutants of Aspergillus niger were isolated by observing the hydrolysis of starch in the petriplates. Of all the mutants tested, the mutant strain of Aspergillus niger GCBU-25, isolated after 25 minutes of UV irradiation gave the maximum production of AMG (136.1 IU/ml/min), which was two fold increase in the production of the enzyme than the parental strain. The production of AMG reached maximum (183 IU/ml/min) when starch at 1% level and (NH4)2SO4 at 0.2% level of nitrogen was used as carbon and nitrogen source respectively.
 
 
 
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