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Articles
by
Asad-ur-Rehman |
Total Records (
3 ) for
Asad-ur-Rehman |
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Asad-ur-Rehman
,
Sikander Ali
and
Ikram-ul-Haq
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Twenty-five strains of Aspergillus niger, isolated from different soil samples were evaluated for citric acid production. Shake flask technique was employed for screening of the isolated. The best citric acid producing strain, GCB-14, was selected for further studies using a laboratory scale stirred fermentor. Cane-molasses medium and sucrose salt medium were tested for the basal fermentation medium. The results indicated that maximum amount of citric acid i.e. 55.43 gl-1 was produced 144 h after incubation using cane-molasses medium. The maximum amount of sugar consumed and dry cell mass produced were 126 and 27.49 gl-1, respectively. Therefore, cane-molasses was optimized as the basal fermentation medium for maximal citric acid production. |
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Saima Karamat
,
Asad-ur-Rehman
,
Ambreen Sadiq
,
Sikander Ali
,
Kiran Shafiq
and
Ikram-ul-Haq
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In the present investigation, the effect of various nitrogen sources and their concentration on citrate fermentation by Yarrowia lipolytica NRRL 143 was studied and the results were analyzed kinetically. Of the three nitrogen sources i.e NH4NO3, NH4Cl and (NH4)2SO4, Ammonium nitrate in 0.3 % concentration gave maximum production of citric acid during the course of study i.e. 31.12?0.1. The product and growth yield coefficients such as Yp/s and Yp/x were found to be quite significant. |
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Hamad Ashraf
,
Asad-ur-Rehman
and
Ikram-ul-Haq
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The present study is concerned with the effect of alcohols such as ethanol and methanol on the biosynthesis of citric acid by Aspergillus niger strain GCB-3. Methyl alcohol in the concentration of 25 ml kg-1 of the substrate gave maximum production i.e. 45.85 g kg-1 while when ethanol was added the maximum production achieved was 40.65 g kg-1. The sugar consumption was 111g kg-1 and 110 g kg-1 respectively. The kinetic parameters such as product yield coefficient (Yp/x), and volumetric rate for product formation (Qp) and substrate consumption (Qs) were also found to be significant at 25 ml kg-1 methanol concentration. |
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