Tan Hao, Tang Jie, Li Xiaolin, Liu Tianhai, Miao Renyun, Huang Zhongqian, Wang Yong, Gan Bingcheng, Peng Weihong
National-Local Joint Engineering Laboratory of Breeding and Cultivation of Edible and Medicinal Fungi, Soil and Fertilizer Institute, Sichuan Academy of Agricultural Sciences, Chengdu 610066, P.R. China.
Scientific Observing and Experimental Station of Agro-microbial Resource and Utilization in Southwest China, Ministry of Agriculture, Chengdu 610066, P.R. China.
J Microbiol Biotechnol. 2017 Dec 28;27(12):2180-2189. doi: 10.4014/jmb.1708.08007.
Psychrophilic phytases suitable for aquaculture are rare. In this study, a phytase of the histidine acid phosphatase (HAP) family was identified in , a psychrophilic mushroom. The phytase showed 38% identity with PhyB, which was the closest hit. The phytase was overexpressed in , purified, and characterized. The phytase had an optimum temperature at 25°C, which is the lowest among all the known phytases to our best knowledge. The optimum pH (6.5) is higher than most of the known HAP phytases, which is fit for the weak acidic condition in fish gut. At the optimum pH and temperature, MiPhyA showed the maximum activity level (2,384.6 ± 90.4 μmol·min⁻¹·mg⁻¹, suggesting that the enzyme possesses a higher activity level over many known phytases at low temperatures. The phytate-degrading efficacy was tested on three common feed materials (soybean meal/rapeseed meal/corn meal) and was compared with the well-known phytases of and . When using the same amount of activity units, MiPhyA could yield at least 3× more inorganic phosphate than the two reference phytases. When using the same weight of protein, MiPhyA could yield at least 5× more inorganic phosphate than the other two. Since it could degrade phytate in feed materials efficiently under low temperature and weak acidic conditions, which are common for aquacultural application, MiPhyA might be a promising candidate as a feed additive enzyme.
适用于水产养殖的嗜冷植酸酶很少见。在本研究中，在一种嗜冷蘑菇中鉴定出一种组氨酸酸性磷酸酶（HAP）家族的植酸酶。该植酸酶与最相似的PhyB有38%的同一性。该植酸酶在中过表达、纯化并进行了表征。该植酸酶的最适温度为25°C，据我们所知，这是所有已知植酸酶中最低的。最适pH值（6.5）高于大多数已知的HAP植酸酶，适合鱼类肠道的弱酸性条件。在最适pH值和温度下，MiPhyA显示出最高活性水平（2384.6±90.4μmol·min⁻¹·mg⁻¹），表明该酶在低温下比许多已知植酸酶具有更高的活性水平。在三种常见饲料原料（豆粕/菜粕/玉米粉）上测试了植酸降解效果，并与和的著名植酸酶进行了比较。当使用相同数量的活性单位时，MiPhyA产生的无机磷酸盐至少比两种参考植酸酶多3倍。当使用相同重量的蛋白质时，MiPhyA产生的无机磷酸盐至少比其他两种多5倍。由于MiPhyA可以在水产养殖应用中常见的低温和弱酸性条件下有效降解饲料原料中的植酸，它可能是一种有前途的饲料添加剂酶候选物。
