1. College of Engineering, Peking University, Beijing 100871, PR China
2. Institute of Biology, Henan Academy of Sciences, Zhengzhou 450008, PR China
3. Institute of Engineering (Baotou), College of Engineering, Peking University, Baotou 014030, PR China
4. State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China.