Tseng Y H, Fang T J, Tseng S M
Department of Food Science, National Chung Hsing University, Taichung, Taiwan 40227, Republic of China.
Folia Microbiol (Praha). 2000;45(2):121-7. doi: 10.1007/BF02817409.
Eighty-three isolates from different soil samples exhibited the potential for producing active extracellular phytase. The most active fungal isolate with phytase activity was identified as Penicillium simplicissimum. In shaking culture with enrichment medium, the highest extracellular phytase activity of the producing strain was 3.8 U/mL. The crude enzyme filtrate was purified to homogeneity using ultrafiltration. IEC and gel filtration chromatography. The molar mass of the purified enzyme was estimated to be 65 kDa on SDS-PAGE. The saccharide identification with periodic acid-Schiff reagent (PAS) and activity recognition by 1-naphthyl phosphate was all positive. The isoelectric point of the enzyme, as deduced by isoelectric focusing, was pH 5.8, the optimum pH and temperature being pH 4.0 and 55 degrees C, respectively. The purified enzyme revealed broad substrate specificity and was strongly inhibited by Fe2+, Fe3+ and Zn2+; however, no inhibition was found by EDTA and PMSF. Phytase activity was inhibited when 2 mmol/L of dodecasodium phytate was added and the Km for it was determined to be 813 mmol/L.
从不同土壤样品中分离出的83株菌株表现出产生活性胞外植酸酶的潜力。产植酸酶活性最高的真菌菌株被鉴定为简单青霉。在富集培养基的振荡培养中，产酶菌株的最高胞外植酸酶活性为3.8 U/mL。粗酶滤液通过超滤、离子交换色谱（IEC）和凝胶过滤色谱法纯化至均一。在SDS-PAGE上，纯化酶的摩尔质量估计为65 kDa。用高碘酸-席夫试剂（PAS）进行糖类鉴定以及用1-萘基磷酸酯进行活性识别均呈阳性。通过等电聚焦推导，该酶的等电点为pH 5.8，最适pH和温度分别为pH 4.0和55℃。纯化后的酶显示出广泛的底物特异性，并且受到Fe2+、Fe3+和Zn2+的强烈抑制；然而，未发现EDTA和PMSF对其有抑制作用。当添加2 mmol/L的植酸钠时，植酸酶活性受到抑制，其Km值测定为813 mmol/L。
