1. Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
2. Production Research Institute of Shengli Oilfield Co. Ltd., Dongying 257000, China
3. Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Schuster Building, Manchester M13 9PL, United Kingdom