Hwang W Z, Coetzer C, Tumer N E, Lee T C
Department of Food Science and Center for Advanced Food Technology, and Center for Agricultural Molecular Biology, Rutgers University, Cook College, New Brunswick, New Jersey 08901-8520, USA.
J Agric Food Chem. 2001 Oct;49(10):4662-6. doi: 10.1021/jf0007838.
A 3.6 kb ice nucleation gene (ina) isolated from Erwinia herbicola was placed under control of the galactose-inducible promoter (GAL1) and introduced into Saccharomyces cerevisiae. Yeast transformants showed increased ice nucleation activity over untransformed controls. The freezing temperature of a small volume of water droplets containing yeast cells was increased from approximately -13 degrees C in the untransformed controls to -6 degrees C in ina-expressing (Ina(+)) transformants. Lower temperature growth of Ina(+) yeast at temperatures below 25 degrees C was required for the expression of ice nucleation activity. Shift of temperature to 5-20 degrees C could induce the ice nucleation activity of Ina(+) yeast when grown at 25 degrees C, and maximum ice nucleation activity was achieved after induction at 5 degrees C for approximately 12 h. The effects of Ina(+) yeast on freezing and texturization of several food materials was also demonstrated.
从草生欧文氏菌中分离出的一个3.6 kb的冰核基因（ina）被置于半乳糖诱导型启动子（GAL1）的控制之下，并导入酿酒酵母中。酵母转化体相比于未转化的对照显示出增强的冰核活性。含有酵母细胞的少量水滴的冷冻温度从未转化对照中的约-13℃提高到ina表达（Ina(+)）转化体中的-6℃。Ina(+)酵母在低于25℃的温度下生长是表达冰核活性所必需的。当在25℃下生长时，将温度转移至5-20℃可诱导Ina(+)酵母的冰核活性，并且在5℃诱导约12小时后达到最大冰核活性。还证明了Ina(+)酵母对几种食品材料的冷冻和质构化的影响。
