The Reaction Of Bacteria In The Deep Sea Sediment To Organic Carbon: Effects On Bac Terial Community And Enzyme Activity

The deep sea sediment samples used in this study were collected from the west Pacific Warm Pool with depth from 2900m to 5080m by cruises "DY105-11", which was organized by China Mineral Resources Association. The Antarctic soils were collect during the 19th scientific review in the Antarctic.The deep sea plays a major role in the global cycling of elements and contains a large reservoir of organic carbon. It plays an important role in climate changes.Deep sea sediments, covering more than 60% of the earth surface, represent the largest Earth's ecosystem. The Antarctica is an important cold headstream in global cold and heat circulation and important driving force of global climate change, They all are cold environments in the surface of the Earth. Resource of microorganisms in the deep sea and Antarctic is abundant and their microbial ecology study is of great importance.Bacteria are the aboundant component and the major players of biogeochemical transformations.Bacteria are responsible for important processes including nutrient cycling and organic matter breakdown either by physiological adaptation or by changes in the community composition. Sediments amended with organic matters consistently register significant greater enzyme activities and alterable community structure of bacteria. Enzyme activity was evaluated by analyzing the specific PNP substrate. The differences in diversity of the bacterial communities at the different sites are determined by DGGE and by cultivation-based methods. Biochemical and molecular ecology data suggest that bacteria will response to the organic matter by changing community structure and regulation of enzyme. In the deep sea sediment, there are five domain,G+ bacteria, α -proteobacterium, β-proteobacterium, γ-proteobacterium, Euryarchaeota. whereas in the Antarctic soils, α-proteobacterium, γ-proteobacterium, ε -proteobacterium, G+ are dominant, especially G+ bacteria. Input organic matter make positive effect to the deep sea sediment bacteria community, otherwise make negative effect to the Antarctic soil bacteria community.By cultivation-based methods, 86 psychrotrophs, which were affiliated to 18 genera and have different physiological characteristics, were screened out as lipolytic bacteria. Six strains affiliated to Psychrobacter, have similar 16srDNA sequence ,but have different enzyme produce line, whereas they have at least three lipase (35kDa, 65kDa, 85kDa).The deep-sea strains from different genus Psychrobacter sp. wp37 and Pseudoalteromonas sp. wp27 had the highest lipase production when grown at 10 to 20 °C; Lipases from both strains had the same optimal reaction temperature and pH (20-30 °C, pH 7-8) and could retain about 60% of their highest activity at 4°C. Further SDS-PAGE and an in-gel activity test showed that they had the same unusually high molecular mass of about 85 kDa. There may be "gene flow" mechanism between different strains.