We thank Emeritus Prof. Keisuke Tubaki of University of Tsukuba for his encouragement and fruitful discussion throughout this work. Thanks are also due to Mr. Kiyoshi Iguchi of Hiraoka Environmental Institute, Ms. Yuriko Adachi, Mr. Akito Koyama, Mr. Akito Koyama for collecting the specimen.  We also thank Drs. Kadri Poldmaa of University of Tartu, Estonia and Gary J. Samuels of USDA-ARS, USA who kindly allowed us to examine their cultures.