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Articles by Sikander Ali
Total Records ( 21 ) for Sikander Ali
  Kiran Shafiq , Sikander Ali and Ikram-ul-Haq
  The effect of different mineral nutrients was studied on the production of extracellular invertases by Saccharomyces cerevisiae GCB-K5. Nutritional studies were carried out in 250ml Erlenmeyer flasks by submerged fermentation. The culture medium (pH 6.0) was incubated for 48 hours at 30oC. The optimum levels of peptone and dipotassium hydrogen phosphate were found to be 4.0 and 0.2 g/l, respectively. Maximum invertase activity was found to be 12.68 U/ml. The amount of sugar consumed and dry cell mass were 21.08 and 5.88g/l, respectively.
  Ikram-ul-Haq , Hamid Mukhtar , Sunila Daudi , Sikander Ali and M. A. Qadeer
  Thirteen mould cultures, capable of producing proteases by solid state fermentation, were isolated from soil. Rhizopus oligosporus IHS13 strain was found to be the best producer of acidic proteases. The agricultural by-products namely sunflower meal, wheat bran, soybean meal, lupin cake and cotton seed meal were evaluated as inducers for the production of enzyme. The enzyme synthesis was maximum when sunflower meal was used as substrate. The production of proteases by Rhizopu s oligosporus HIS13 strain was studied by varying the size of inoculum and type of diluent. The optimum inoculum size and diluent were 10% and distilled water, respectively. The effect of different buffers on the extraction of enzyme was also studied and distilled water was found to be the best extractor. The maximum enzyme production, obtained during the course of study was 4.8 U ml-1.
  Ayesha Khan , Ikram-ul-Haq , Waseem Ahmad Butt and Sikander Ali
  Present investigation deals with the isolation and screening of Aspergillus niger isolates for the biosynthesis of xylanase. About 104 different strains of Aspergillus niger were isolated from soil collected from different areas of Lahore by serial dilution method on xylene agar malt extract medium. The strains with larger whitish zones of xylene hydrolysis were picked up and transferred to the PDA slants. The cultures were incubated at 30°C for 3-5 days for maximal sporulation. The Aspergillus niger strains were screened for xylanase production by submerged fermentation. Xylanase activity was ranged from 30-225 U ml-1 and dry cell mass from 6.48-26.56 g L-1. Maximum xylanase productivity was obtained by GCBT-35 (225 U ml-1). The mycelial dry weight was 9.54 g L-1 while mycelia were small in size and rounded in shape.
  Asad-ur-Rehman , Sikander Ali and Ikram-ul-Haq
  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.
  Ikram-ul-Haq , Uzma Hameed , Kiran Shahzadi , M. Mohsin Javed , Sikander Ali and M.A. Qadeer
  The present study deals with the optimization of cultural conditions for Cotton Saccharifying Activity (CSA) of cellulases by Trichoderma harzianum UM-11 using shake flask technique in 250 mL Erlenmeyer flasks. Among the different fermentation media tested, Carboxymethyl Cellulose (CMC) with Mineral Salts Solution (MSS) gave the best CSA. Cotton saccharification was optimal when 25 mL of the medium was incubated at 28°C for 96 h. The maximum CSA (0.528 U/mL/h) was found at initial pH 6.0. The level of inoculum was optimized at 5.0x107 conidia/25 mL medium.
  Ikram-ul-Haq , Nuzhat Inam , Sikander Ali and M.A. Qadeer
  Microbial examination of 50 samples of both packed and unpacked butter was carried out. The samples were examined for total viable count, mould and yeast count, spore formers and coliform. The microbial load in the unpacked sample of butter was highest i.e., 3.8 × 106/gm - 6.6 × 106/gm. The coliform count was found maximum in unpacked sample and one of the packed sample of butter (Kausar brand) i.e., 39/ml. The unpacked sample of butter contained highest number of aerobic spore formers i.e., 280/gm. The anaerobic spore-formers were found absent in 20 samples of butter and the rest contained in the range of 0-170/gm. The yeast cultures were found only in the sample of Lyallpur and Kausar butter. The mould count of these samples ranged from 0-280/gm.
  Sikander Ali and Ikram-ul-Haq
  Effect of Cu2+ were studied ions on the growth morphology and citric acid production from blackstrap molasses by Aspergillus niger GCB-47. The addition of 0.02% CuSO4 to the fermentation medium reduced the Fe2+ ions conc. by counter-acting its deleterious effect on fungal growth. The Cu2+ ions also induced a loose-pelleted form of growth, reduced the biomass concentration and increased the volumetric productivity.
  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 , Ayesha Khan , Waseem Ahmad Butt , Sikander Ali and M. A. Qadeer
  The present study is concerned with the effect of carbon and nitrogen sources and their concentrations on the production of xylanase by mutant strain of Aspergillus niger GCBMX-45. High xylanase activities (2350 U/g) were observed when starch (2%) was used as carbon source. (NH4)2SO4 (0.2%) was found to be best nitrogen source for optimum enzyme production i.e., 2480 U/g. The production of enzyme reached maximum, 72 hours after inoculation. All the fermentations were carried out at 30°C at 0.4 cm (10g wheat bran) depth of the basal medium.
  Aamir Ishaq , Sikander Ali , Ikram-ul-Haq and M.A. Qadeer
  The present study is concerned with the time course profile of citric acid fermentation by Aspergillus niger and its kinetic reletions. Maximum amount of anhydrous citric acid (70.60 g l-1) obtained, 144 h after inoculation, with a sugar consumption of 88.40 g l-1. The dry weight of mycelia was 17.39 g l-1. On the basis of comparison of kinetic parameters namely the product and growth yield coefficients (Yp/s, Yp/x), volumetric rates (Qq) and specific rate constants (qp), it was observed that mutant strain of Aspergillus niger GCB47 was a faster growing organism and has the ability to hyper produce citric acid.
  Kiran Shafiq , Sikander Ali , Amna Ehsan and Ikram-ul-Haq
  The present study concerns with the optimization of inoculum level for invertase production by Saccharomyces cerevisiae GCB-K5. The thermal inactivation of yeast invertase and effect of pH, utilizing the measurements of enzyme activity, was also estimated. Nutritional studies were carried out in 250 ml Erlenmeyer flasks by submerged fermentation. The fermentation medium (pH 6.0) was kept at 30°C for 48 h after inoculation and agitation rate was 200 rpm. Enzyme production was reached maximum (7.1 U ml-1) at 4% inoculum (v v-1). Sugar consumption and dry cell mass were 21.13 and 5.93 mg ml-1, respectively. Comparison of product and growth yield coefficients was also significant for invertase biosynthesis.
  Rubina Mazhar , Sikander Ali , Ikram-ul-haq and Abdul Waheed
  The present study was conducted on the optimization of cultural conditions for the production of citric acid by mutant strain of Aspergillus niger NG-110 by using shake flask technique. Different cultural conditions such as alcohol (1% methanol) and calcium chloride (2%) were optimized for enhanced citric biosynthesis. The results showed that maximum amount of anhydrous citric acid (81.21 ± 0.2 gl -1) was obtained after 168 h inoculation, with a sugar consumption of 92.20 ± 3.5 gl -1. The dry weight of mycelia was 20.40 ± 0.2 gl -1. On the basis of comparison of kinetic parameters namely the product and growth yield coefficients (Yp/s, Yp/x), volumetric rates (Qp) and specific rate constants (qp), the mutant strain of Aspergillus niger NG-110 was a faster growing organism and had the ability to hyper produce citric acid.
  Mirza Ahsen Baig , Kiran Shafiq , Shazia Mirza , Sikander Ali and Ikram-ul-Haq
  Saccharomyces species GCA-II was used to investigate the effect of mineral constituents on the production of β -fructofuranosidase in submerged fermentation. Different organic nitrogen and phosphate sources in varied concentrations were tested for optimal production of enzyme. The results indicated that enzyme production increased from 107.42 to 168.58 U ml-1. Thus, Saccharomyces strain GCA-II gave maximal β -fructofuranosidase in submerged fermentation when urea (3.0 g l-1) as a nitrogen source and K2HPO4 (0.20 g l-1) as phosphate source was supplied in fermentation medium.
  Kiran Shafiq , Sikander Ali and Ikram-ul-Haq
  The present investigation deals with the time course study of three different of Saccharomyces cerevisiae (GCB-K5, GCA-II and KR18) during invertase production by submerged fermentation. GCA-II was found to be the best producer of invertase (8.35 U ml‾1, 48 h after inoculation) having high production yield coefficients (i.e., Yp/s and Yp/x). The product is a high cost product. Thus the use of optimized strain for invertase production is economically more feasible due to shorter incubation period and optimal production.
  Umar Farooq Awan , Shazia Mirza , Kiran Shafiq , Sikander Ali and Ikram-ul-Haq
  The present study is concerned with the biosynthesis of lipase by Rhizopus oligosporous ISUUV-16 through solid-state fermentation. The optimal substrate for the biosynthesis of lipase was almond meal at the level of 10 g per 250 ml Erlenmeyer flask. The optimal lipase production was obtained when incubated at 300C, for 48 h. Maximal lipase activity of 54 Ug-1 was reached at 1 % level of inoculum. Water was used as diluent for enzyme extraction from fermented mash. Substrate to diluent ratio was kept at 1:0.7.
  Saima Karamat , Asad-ur-Rehman , Ambreen Sadiq , Sikander Ali , Kiran Shafiq and Ikram-ul-Haq
  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.
  Kiran Shafiq , Ikram-ul-Haq and Sikander Ali
  The influence of the age and amount of the inoculum on invertase synthesis by Saccharomyces cerevisiae KR18 was studied during submerged cultivation. Fermentation was carried out at 30oC in fermentation medium containing sucrose, yeast extract and peptone at initial pH 6.0 at 200 rpm. The maximum production of invertase (6.9 U ml-1) was obtained when 1.0 ml vegetative inoculum (4 %), developed for 12 h, was used per 25 ml of fermentation medium. The dry cell mass and sugar consumption were 3.0 and 16.18 mg ml-1, respectively. The specific growth and product rates (h-1) are more encouraging to use 4 % vegetative inoculum under optimized conditions.
  Ayesha Khan , Sikander Ali and Ikram-ul-Haq
  The present study is concerned with the optimization of cultural conditions for maximum conversion of L-Tyrosine to L-DOPA by strain of Aspergillus oryzae ISB-9. The effect of time course, temperature and pH on the production of L-DOPA was checked. Surface culture method was employed for L-DOPA fermentation. Optimum temperature and time for L-DOPA production is 50 C and 60 minutes respectively. However, the optimum pH of mycelium development was 5.0 because maximum production of L-DOPA (0.95 mg ml-1) was observed at this pH. The acidic pH (3.0) of reaction mixture was found to be optimum for higher L-DOPA production (1.1mg ml-1).
  Mirza Ahsen Baig , Kiran Shafiq , Sikander Ali , Shazia Mirza , Zafar Siddiq and Ikram-ul-Haq
  The enzyme βfructofuranosidase attacks beta-D-fructofuranoside (raffinose, stachyose and sucrose) from the fructose end. Saccharomyces GCA-II was used for the production of βfructofuranosidase by submerged fermentation. The effect of sucrose concentration and incubation time was worked out for maximal enzyme production. Sucrose at the level of 30.0 g l-1 in fermentation medium was found to exert an inducible effect on enzyme synthesis by Saccharomyces strain after 48 h of inoculation. Enzyme production increased from 107.42 U ml-1 to 118.58 U ml-1 after optimization of the cultural conditions. Specific product rate and specific growth rate were also determined for the production of βfructofuranosidase by Saccharomyces in shake flask.
  Asad-ur- Rehman , Sikander Ali and Ikram-ul-Haq
  In the present investigation, the Aspergillus niger mutant UV-M9 was evaluated using phosphate limitations for enhanced citric acid production. Of the three phosphate sources, K2HPO4 was found to be the best yielding 75.25 gl-1 of anhydrous citric acid. The sugar consumption was 112.5 gl-1 while dry cell mass produced was 18.00 gl-1. The mycelia were small pellets.
  Mirza Ahsen Baig , Kiran Shafiq , Shazia Mirza , Sikander Ali and Ikram-ul-Haq
  The primary application of invertase from Saccharomyces cerevisiae is in the confectionary industry. In Pakistan, much of this enzyme is imported. The influence of the carbon source during invertase production is well known, but little is understood about the nitrogen source influence. We examined three different nitrogen sources using Saccharomyces cerevisiae strain for invertase production. Saccharomyces species GCA-II was used to investigate the effect of urea and other nitrogen sources on the production of β-fructofuranosidase in submerged fermentation. It was found that when a very little amount of urea was added to the fermentation medium it showed marked increase in β-fructofuranosidase production i.e., from 121.35 to 158.26 U/ml.
 
 
 
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