1. Yunnan Institute of Microbiology, Yunnan University, Kunming, Yunnan 650091, PR China
2. College of Resources and Environment, Northwest A & F University, 712100 Yangling, Shaanxi, PR China
3. Leibniz-Institut für Meereswissenschaften, IFM-GEOMAR, Düsternbrooker Weg 20, D-24105 Kiel, Germany