1. Department of Biology, College of Natural Sciences, Sunchon National University, Sunchon 540-742, Republic of Korea
2. School of Biological Sciences and Institute of Microbiology, Seoul National University, NS70, 56-1 Shillim-dong, Kwanak-gu, Seoul 151-742, Republic of Korea
3. Department of Dental Hygiene, Kwangyang Health College, Kwangyang 545-703, Republic of Korea
4. Korea Research Institute of Bioscience and Biotechnology, Yusung PO Box 115, Taejon 305-600, Republic of Korea