دانلود رایگان ترجمه مقاله تخلیص و مشخصات فیتاز از باسیلوس سوبتیلیس (نشریه تیلور و فرانسیس ۱۹۹۲)

تخلیص و مشخصات فیتاز از باسیلوس سوبتیلیس (ناتو) N–۷۷

Purification and Characterization of Phytase from Bacillus suhtilis (natto) N–۷۷

An extracellular phytase from Bacillus subtilis (natto) N-77 was purified 322-fold to homogeneity with the specific activity of 8.7 units per mg protein by ultrafiltration, and a combination of Sephadex G-IOO and DEAE-Sepharose CL-6B column chromatographies. The molecular weight of the purified enzyme was estimated to be 36 kDa on gel filtration and 38 kDa on SDS-polyacrylamide gel electrophoresis, suggesting that the native enzyme is a monomeric protein. The enzyme had the isoelectric point of pH 6.25, and Ca2 + requirement for the production and activity, the Km value of 0.5 mM, and the activation energy of 9.87 kcal/mol for sodium phytate. The enzyme proved to be fairly specific for phytate and was most active at pH 6.0-6.5 and 60°C. Its activity was greatly inhibited by reagents and metal ions such as EDT A, Zn2 +, Cd2 +, Ba2 +, Cu2 +, Fe2 +, and AI3 +.

Phytic acid (myo-inositol 1,2,3,4,5,6·hexakis dihydrogen phosphate) is the major storage form of phosphorus in cereals and legumes, representing 18 to 88% of the total phosphorus. I) Phytate form of phosphorus is not readily utilizable by monogastric animals2 ) and results in contribution to phosphorus pollution problems in areas of intensive livestock production. The interaction of phytic acid with essential dietary minerals, protein, or vitamins is considered to be one of the primary factors limiting the nutritional values of cereals and legumes in man and animals. 3 ) Attempts4 – 7) have been made to hydrolyze dietary phytate by phytases to improve the feed quality and to decrease in the amount of phosphorus excreted by animals. Partially purified microbial phytase preparations have been reported in Aerobacter aerogenes,8) Pseudomonas Sp.,9) Aspergillus niger, 10) and Aspergillus oryzae. ll ) However, characteristics of homogeneous enzyme preparations have been elucidated only in a few microorganisms such as Aspergillus terreus,12,13) Aspergillus ficuum, 14) and Bacillus subtilis. 15 )

Bacillus subtilis (natto) strains’ grow well on steamed soybeans, which are rich in phytate, without any additional nutrition, and can actively ferment those to natto, a traditional soybean cheese in Japan. Therefore, I attempted to survey whether B. subtilis (natto) strains produce potential hydrolytic enzymes for phytate in soybeans, and have found that most of the B. subtilis (natto) isolates from commercial natto samples actively produced phytase. This paper describes purification and characterization of B. subtilis (natto) phytase in relation to other microbial phytases.