1. School of Life Science and Agriculture and Forestry; Qiqihar University; Qiqihar 161006 China
2. Department of Microbiology and Plant Biology; Institute for Environmental Genomics, University of Oklahoma; Norman Oklahoma 73072 USA
3. State Key Laboratory of Lake Science and Environment; Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences; Nanjing 210000 China