1. College of Food Science; Sichuan Agricultural Univ; Ya'an Sichuan 625014 P. R. China
2. The Lab of Microbiology; Sichuan Agricultural Univ; Dujiangyan Sichuan 611830 P. R. China
3. Dept. of Food Science; Louisiana State Univ. Agricultural Center; 111 Food Science Building Baton Rouge La. 70803 U.S.A