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Articles by U.O. George-Okafor
Total Records ( 3 ) for U.O. George-Okafor
  U.O. George-Okafor , F.O. Tasie and N.C. Anyamene
  The need for starch-converting enzymes in various industries has led to enormous interest in their production at a cheap rate. The present study was focused on the examination of various inexpensive substrates and other production parameters for amylase production by the most potential selected strain. It was observed that A. oryzae-SR2 was the best amylase producer (36.31±0.24 mm) among other Aspergillus isolates when screened by starch hydrolysis test. Preliminary submerged fermentation using soluble starch medium confirmed the potentials of A. oryzae-SR2 for amylase production. The maximum enzyme production under submerged fermentation was achieved with 0.5% sugar-cane juice supplemented with 0.5% dry-flakes fermented tapioca, 1% yeast extract, 7% inoculums concentration, pH 7.0, temperature of 55°C and incubation period of 48 h. The enzyme demonstrated strong hydrolytic activities (56.4%) on the tested starchy foods with cassava starch being the most hydrolyzed (101.5%) with 86.90±1.10% conversion efficiency at 70°C. The ability to produce high amount of amylase within a relatively short time (48 h) using cheap substrates and the ability of its enzyme to effectively hydrolyze starchy foods suggests its suitability for biotechnological application especially in starch-converting industries.
  U.O. George-Okafor and F.J.C. Odibo
  There are limited reliable information on the commercial production and utilization of proteases for detergent and other industrial uses in Nigeria. Hence, the purification and characterization of Bacillus sp. Gs-3 protease for its potential industrial uses were investigated. The dialyzed crude enzyme was purified 17-fold in a two-step procedure involving carboxymethyl sepharose ionic-exchange chromatography and phenyl sepharose 6-fast flow hydrophobic interaction chromatography. The purified enzyme had its optimal activity at pH 9.0 and 90°C and was stable over a pH range 8.0-11.0. It readily hydrolyzed all the tested protein substrates but exhibited highest affinity for gelatin (Km 0.15 mg mL-1). It retained at least 66.2±0.02% of its original activity in the presence of the tested local commercial detergents and removed bloodstains completely. Its activity was significantly (p>0.05) enhanced by Cu2+ ion but strongly inhibited (75.6±0.07%) by Phenyl-methyl Sulfonyl Fluoride (PMSF). Thus, the enzyme demonstrated desirable properties suitable for its biotechnological applications especially in detergent industry.
  U.O. George-Okafor and E.E. Mike-Anosike
  The production of most bacterial proteases has always been with expensive refined substrates which tend to increase the production cost. Hence, a low-cost substrates and culture conditions capable of optimizing protease production by an isolated Bacillus sp. were studied. Bacillus sp. SW-2 which demonstrated the highest protease activity was selected and used for protease production by shake-flask fermentation technique at 180 rpm. The maximum protease yield for 72 h (2.697±0.19 IU mL-1) was achieved under optimized culture conditions of pH 9.0, temperature of 45°C and 5% inoculums density with soy meal (1%) and sugar cane bagasse (1%) as nitrogen and carbon sources of the fermentation medium. The protease yield obtained from using the cheap substrates at 72 h incubation was significantly (p>0.05) higher than that obtained from expensive substrates. The protease achieved >85.7±0.08% hydrolytic activities on the tested nitrogen wastes with soybean waste being the mostly hydrolyzed (96.3±0.13%). This result indicated the use of soy meal and sugar cane bagasse as rich substrates for maximum protease yield and the enzyme hydrolytic activity on nitrogen wastes suggests its application in environmental waste degradation.
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