假丝酵母尿酸酶形成条件

选出了一株产尿酸酶的产朊候丝酵母(Candida utilis)AS2．117。此菌株尿酸酶形成条件的研究表明：尿酸、黄嘌呤和鸟嘌呤对酶形成起诱导作用；玉米浆对菌株生长和酶形成起十分重要的作用；蔗糖、葡萄塘、D-甘露糖和果糖是酶形成的适合碳源；生物素对酶产生有促进作用；在含有玉米浆培养基中加入无机氮源对产酶无作用，添加有机氮略增加产酶量。尿酸酶形成最适培养基组成为(％)：蔗糖；，玉米浆3，尿酸0．1，蛋白胨0．1，生物素0．05，KCI0．1，NaCl 0.1。最适pH为6．2。在250ml三角瓶中装30ml培养基为最适。在200r／min的旋转摇床上25℃振荡培养21h，在此条件下最终酶活力可达0．6u／ml。

Culture conditions for uricase formation of Candida utilis

A uricase producing strain, Candida utilis AS 2.117, was screened out and the uricase-forming conditions have been investigated. The results are obtained as follows: uric acid, xanthine and guanine were found to be effective inducers for enzyme formation. Corn steep liquor was essential for enzyme formation and cell growth. Sucrose, glucose, D-mannose and D-fructose were the suitable carbon sources for enzyme formation. To the medium containing corn steep liquor, addition of inorganic nitrogen sources was harmful to the enzyme formation, however, addition of organic nitrogen sources enhanced enzyme activity slightly. The suitable medium for uricase formation was consisted of sucrose 5%, corn steep liquor 3%, uric acid 0.1%, proteose-peptone 0.1%, biotin 0.05%, KCl 0.1%, NaCl 0.1% at pH 6.2. When the yeast was grown in 250 ml conic flask containing 30 ml of the medium mentioned above on the rotary shaker (200 r/min) at 25 degrees C for 21 h, uricase with 0.6 u/ml activity was obtained.