The Experts below are selected from a list of 177 Experts worldwide ranked by ideXlab platform
Fazheng Ren - One of the best experts on this subject based on the ideXlab platform.
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Screening fermentation parameters of the milk-clotting enzyme produced by newly isolated Bacillus amyloliquefaciens D4 from the Tibetan Plateau in China
Annals of Microbiology, 2011Co-Authors: Zhang Weibing, Fazheng Ren, Bozhong Gan, Huiyuan GuoAbstract:A bacterium producing an extracellular milk-clotting enzyme was isolated from yak grazing soil in the Tianzhu Tibetan autonomous county on the Tibetan Plateau and identified as Bacillus amyloliquefaciens. We used single-factor testing to study the optimum physical conditions and nutritional parameters for production of the milk-clotting enzyme, while the temperature and pH stability of the enzyme were also studied. The optimum conditions for production of the milk-clotting enzyme were: temperature, 37°C; inoculum size, 4% (1.8 × 107 CFU/mL); agitation speed, 170 rpm; and initial pH of the medium, 6.2. The maximum milk-clotting activity and milk-clotting activity per proteolysis activity were found using wheat bran juice at a concentration 18 g/100 mL, 4% (w/v) sucrose and 2% (w/v) skim milk powder. These optimized conditions resulted in a 2.68-fold increase in production of the milk-clotting enzyme. The crude enzyme exhibited good temperature and pH stability; 80% of the milk-clotting activity was retained after incubation at 40°C for 30 min and more than 70% of the activity was retained between pH 5.5 and 7.5. This B. amyloliquefaciens milk-clotting enzyme has potential as a calf Rennet Substitute.
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Purification, characterization, and milk coagulating properties of ginger proteases
Journal of dairy science, 2011Co-Authors: X.w. Huang, Huiyuan Guo, Longjian Chen, Yunbo Luo, Fazheng RenAbstract:Abstract Ginger proteases are used as milk coagulants in making a Chinese traditional milk product (Jiangzhinai or Jiangzhuangnai), suggesting their potential as a source of Rennet Substitute that might be applicable in the modern dairy industry. In this study, ginger proteases were extracted from fresh ginger rhizome by using phosphate buffer and subsequently purified by ion exchange chromatography. Ginger proteases, all with a molecular weight around 31kDa, were found to exist in 3 forms with isoelectric point values around 5.58, 5.40, and 5.22, respectively. These enzymes had very similar biochemical behavior, exhibiting optimal proteolytic activity from 40 to 60°C and maximum milk clotting activity at 70°C. They were capable of hydrolyzing isolated α S1 -, β-, and κ-casein, of which α S1 -casein was most susceptible to the enzyme; κ-casein was hydrolyzed with a higher specificity than α S1 - and β-casein. In addition, the ginger proteases exhibited a similar affinity for κ-casein and higher specificity with increasing temperature. Gel electrophoresis and mass spectra indicated that Ala90-Glu91 and His102-Leu103 of κ-casein were the preferred target bonds of ginger proteases. The milk clotting activity, affinity, and specificity toward κ-casein showed that ginger protease is a promising Rennet-like protease that could be used in manufacturing cheese and oriental-style dairy foods.
Mohamed A. Abdel-naby - One of the best experts on this subject based on the ideXlab platform.
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Statistical optimization of B. subtilis MK775302 milk clotting enzyme production using agro-industrial residues, enzyme characterization and application in cheese manufacture
Biocatalysis and Agricultural Biotechnology, 2020Co-Authors: Hala R. Wehaidy, Walaa A. Abdel Wahab, Adel M.m. Kholif, Mostafa Elaaser, Wafaa K. Bahgaat, Mohamed A. Abdel-nabyAbstract:Abstract The agricultural and industrial wastes are environmental pollutants. So, there is an increasing demand for more efficient exploitation of these wastes and their conversion into useful products. Recently, the limited availability of calf Rennet led to a search for Rennet Substitutes for cheese manufacture. In this study, Bacillus subtilis subsp. subtilis strain 168 (B. subtilis MK775302) was isolated from the marine sponge Pseudoceratina Arabica and it was used for milk clotting enzyme (MCE) production using some agro-industrial wastes. The production medium containing agro-industrial residues was optimized by using Plackett-Burman (PB) and central composite designs (CCD). After optimization, the MCE productivity was increased by 2.3-fold compared to the non-optimized medium. The enzyme showed maximum activity at 70 °C, pH 5.0. Ultrafilterated (UF) white soft cheese production was studied by using the crude extract of B. subtilis MK775302 in a comparison with commercial Rennet. The cheese produced by the crude extract of B. subtilis MK775302 had a higher ripening index, higher acidity, higher flavor intensity, and acceptable organoleptic score. Therefore, this study offered the production of a promising Rennet Substitute that is eco-friendly with low production costs and competes with the commercial coagulants for the production of acceptable UF white soft cheese.
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Optimization of the production and characterization of milk-clotting enzyme from Bacillus subtilis isolated from marine sponge
Egyptian Pharmaceutical Journal, 2016Co-Authors: Hala R. Wehaidy, Mohamed A. Abdel-naby, Wafaa Gh. Shousha, Mohammed I.y. El Mallah, Michael Mounir ShawkyAbstract:Background and objectives Milk-clotting enzyme (MCE) has important applications in the dairy industry and in the cheese-manufacturing process. Because of the increase in cheese consumption and the low supply of calf Rennets, there is a need for a suitable Rennet Substitute from an appropriate source. The present investigation aims at microbial production of MCE and medium optimization for maximal enzyme production by the most potent strain. Partial purification and the properties of the partially purified enzyme are also studied. Materials and methods In the present study several microorganisms were tested for production of the MCE. MCE/caseinase ratio was investigated and was used as the key parameter for selection of the most potent strain and for medium optimization. Medium optimization experiments were carried out in an attempt to increase the enzyme productivity by the most potent strain. The produced enzyme was partially purified using ammonium sulfate at 50% concentration and the properties of the partially purified enzyme were investigated. Results and conclusion Among all the tested bacteria the marine sponge Pseudoceratina arabica isolated bacterium (isolate I) showed the highest milk-clotting activity. This isolate was used for MCE production throughout this study and it was identified as Bacillus subtilis KU710517. Maximum enzyme productivity (581.8 U/ml) and maximum MCE/caseinase ratio were obtained using a medium containing 50 g/l wheat bran with xylose and yeast extract as carbon and nitrogen sources. For the partially purified enzyme, the optimal temperature and pH were 85°C and 5.0, respectively. The enzyme was thermally stable at 45°C and retained 100% activity after 90 min. At 50°C for the same period of time it retained about 82% activity. However, at 60°C, the enzyme lost about 70% of its original activity after 30 min. The activation energy (Ea) of the enzyme was calculated as 6.95 kcal/mol. Km and Vmax values were 4.6 mg/ml and 2933 U/mg protein, respectively.
Chen Xiaohong - One of the best experts on this subject based on the ideXlab platform.
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Ginger rhizome as a potential source of milk coagulating cysteine protease.
Phytochemistry, 2011Co-Authors: Malik Muhammad Hashim, Dong Ming-sheng, Muhammad Iqbal, Chen XiaohongAbstract:Abstract A milk coagulating protease was purified ∼10.2-fold to apparent homogeneity from ginger rhizomes in 34.9% recovery using ammonium sulfate fractionation, together with ion exchange and size exclusion chromatographic techniques. The molecular mass of the purified protease was estimated to be ∼36 kDa by SDS–PAGE, and exhibited a p I of 4.3. It is a glycoprotein with 3% carbohydrate content. The purified enzyme showed maximum activity at pH 5.5 and at a temperature of ∼60 °C. Its protease activity was strongly inhibited by iodoacetamide, E-64, PCMB, Hg 2+ and Cu 2+ . Inhibition studies and N-terminal sequence classified the enzyme as a member of the cysteine proteases. The cleavage capability of the isolated enzyme was higher for α s -casein followed by β- and κ-casein. The purified enzyme differed in molecular mass, p I , carbohydrate content, and N-terminal sequence from previously reported ginger proteases. These results indicate that the purified protease may have potential application as a Rennet Substitute in the dairy industry.
Hala R. Wehaidy - One of the best experts on this subject based on the ideXlab platform.
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Statistical optimization of B. subtilis MK775302 milk clotting enzyme production using agro-industrial residues, enzyme characterization and application in cheese manufacture
Biocatalysis and Agricultural Biotechnology, 2020Co-Authors: Hala R. Wehaidy, Walaa A. Abdel Wahab, Adel M.m. Kholif, Mostafa Elaaser, Wafaa K. Bahgaat, Mohamed A. Abdel-nabyAbstract:Abstract The agricultural and industrial wastes are environmental pollutants. So, there is an increasing demand for more efficient exploitation of these wastes and their conversion into useful products. Recently, the limited availability of calf Rennet led to a search for Rennet Substitutes for cheese manufacture. In this study, Bacillus subtilis subsp. subtilis strain 168 (B. subtilis MK775302) was isolated from the marine sponge Pseudoceratina Arabica and it was used for milk clotting enzyme (MCE) production using some agro-industrial wastes. The production medium containing agro-industrial residues was optimized by using Plackett-Burman (PB) and central composite designs (CCD). After optimization, the MCE productivity was increased by 2.3-fold compared to the non-optimized medium. The enzyme showed maximum activity at 70 °C, pH 5.0. Ultrafilterated (UF) white soft cheese production was studied by using the crude extract of B. subtilis MK775302 in a comparison with commercial Rennet. The cheese produced by the crude extract of B. subtilis MK775302 had a higher ripening index, higher acidity, higher flavor intensity, and acceptable organoleptic score. Therefore, this study offered the production of a promising Rennet Substitute that is eco-friendly with low production costs and competes with the commercial coagulants for the production of acceptable UF white soft cheese.
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Optimization of the production and characterization of milk-clotting enzyme from Bacillus subtilis isolated from marine sponge
Egyptian Pharmaceutical Journal, 2016Co-Authors: Hala R. Wehaidy, Mohamed A. Abdel-naby, Wafaa Gh. Shousha, Mohammed I.y. El Mallah, Michael Mounir ShawkyAbstract:Background and objectives Milk-clotting enzyme (MCE) has important applications in the dairy industry and in the cheese-manufacturing process. Because of the increase in cheese consumption and the low supply of calf Rennets, there is a need for a suitable Rennet Substitute from an appropriate source. The present investigation aims at microbial production of MCE and medium optimization for maximal enzyme production by the most potent strain. Partial purification and the properties of the partially purified enzyme are also studied. Materials and methods In the present study several microorganisms were tested for production of the MCE. MCE/caseinase ratio was investigated and was used as the key parameter for selection of the most potent strain and for medium optimization. Medium optimization experiments were carried out in an attempt to increase the enzyme productivity by the most potent strain. The produced enzyme was partially purified using ammonium sulfate at 50% concentration and the properties of the partially purified enzyme were investigated. Results and conclusion Among all the tested bacteria the marine sponge Pseudoceratina arabica isolated bacterium (isolate I) showed the highest milk-clotting activity. This isolate was used for MCE production throughout this study and it was identified as Bacillus subtilis KU710517. Maximum enzyme productivity (581.8 U/ml) and maximum MCE/caseinase ratio were obtained using a medium containing 50 g/l wheat bran with xylose and yeast extract as carbon and nitrogen sources. For the partially purified enzyme, the optimal temperature and pH were 85°C and 5.0, respectively. The enzyme was thermally stable at 45°C and retained 100% activity after 90 min. At 50°C for the same period of time it retained about 82% activity. However, at 60°C, the enzyme lost about 70% of its original activity after 30 min. The activation energy (Ea) of the enzyme was calculated as 6.95 kcal/mol. Km and Vmax values were 4.6 mg/ml and 2933 U/mg protein, respectively.
X.w. Huang - One of the best experts on this subject based on the ideXlab platform.
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Purification, characterization, and milk coagulating properties of ginger proteases
Journal of dairy science, 2011Co-Authors: X.w. Huang, Huiyuan Guo, Longjian Chen, Yunbo Luo, Fazheng RenAbstract:Abstract Ginger proteases are used as milk coagulants in making a Chinese traditional milk product (Jiangzhinai or Jiangzhuangnai), suggesting their potential as a source of Rennet Substitute that might be applicable in the modern dairy industry. In this study, ginger proteases were extracted from fresh ginger rhizome by using phosphate buffer and subsequently purified by ion exchange chromatography. Ginger proteases, all with a molecular weight around 31kDa, were found to exist in 3 forms with isoelectric point values around 5.58, 5.40, and 5.22, respectively. These enzymes had very similar biochemical behavior, exhibiting optimal proteolytic activity from 40 to 60°C and maximum milk clotting activity at 70°C. They were capable of hydrolyzing isolated α S1 -, β-, and κ-casein, of which α S1 -casein was most susceptible to the enzyme; κ-casein was hydrolyzed with a higher specificity than α S1 - and β-casein. In addition, the ginger proteases exhibited a similar affinity for κ-casein and higher specificity with increasing temperature. Gel electrophoresis and mass spectra indicated that Ala90-Glu91 and His102-Leu103 of κ-casein were the preferred target bonds of ginger proteases. The milk clotting activity, affinity, and specificity toward κ-casein showed that ginger protease is a promising Rennet-like protease that could be used in manufacturing cheese and oriental-style dairy foods.