1. Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea
2. Natural Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Cheongwon-gun 363-883, Republic of Korea
3. Department of Food Science and Human Nutrition, Chungnam National University, Daejeon 305-764, Republic of Korea
4. Department of Microbiology, College of Medicine, Seonam University, Namwon 590-711, Republic of Korea