Project description:Dinoflagellate blooms are natural phenomena that have drawn global attention due to their huge negative impacts on marine ecosystems, mariculture and human health. Although the understanding of dinoflagellate blooms has been significantly improved over the past half century, little is known about the underlying mechanisms sustaining the high biomass growth rate during the bloom period which is paradoxically characterized by low dissolved CO2 and inorganic nutrients. Here, we compared the metaproteomes of non-bloom, mid-bloom and late-bloom cells of a marine dinoflagellate Prorocentrum donghaiense in the coastal East China Sea, to understand the underlying mechanisms sustaining high biomass growth rate under the typically low CO2 and inorganic nutrient conditions.
Project description:Marine viral concentrates (VCs) contains a substantial amount of non-cellular biological particles, e.g. viruses, gene transfer agents (GTAs) and membrane vesicles that are ecological significant. Metagenomic sequencing of VCs has been extensively applied to study the diversity and function potential of natural virions whereas information of nonn-viral components are often excluded for investigation. Here we apply a shotgun proteomic approach to characterize the origin and function of proteins in the VCs collected from the deep chlorophyll maximum (DCM) of the South China Sea. Using a custom database, we identified 636 non-redundant proteins represented by a total of 7220 spectra from the two VC samples. Cyanophages, pelagiphages, Phycodnaviridae and a group of uncultured viruses (previouly collected from DCM of Mediterranean Sea) contributed the most in the viral proteome. Seldom proteins related to RNA viruses and known GTAs were found despites of the presence of their sequences in the protein-searching database, suggested that these particles might be low abundant in the samples. Over 60% of identified spectra could not be assigned to viruses. The non-viral spectra were dominated by microbial groups of SAR324, SAR11, Actinobacteria and picoeukaryotic algae such as prasinophytes.Interestingly, we found that periplasmic proteins such as diverse ABC and TRAP transporters, and 56 kDa selenium-binding proteins, were enriched in this fraction.Together with other detected non-viral proteins,we could identify significant microbial functions, such as the utilization of glycine betaine, 3-dimethylsulphoniopropionate,and taurine by SAR11,and urea by prochlorococcus, nitrous oxide production by ammonia-oxidizing archaea and peroxide detoxification by unkonwn gammaproteobacteria. Our study of marine VCs demonstrates the potential application of metaproteomics to link the nano-size materials to the diversity of virions and interesting microbial functions in the ocean.
Project description:Viral concentrates (VCs) contained both viral particles and cell-affiliated components. In this study, a shotgun metaproteomic approach was applied to characterize proteins in the VCs collected from chlorophyll maximum, mesopelagic (200 m) and bathypelagic (3000 m) waters in the South China Sea. Abundant viral proteins indicated the shift of viral community as depth. Whereas the remaining non-viral proteins suggested the diverse microbial metabolism distinct at different layers.
Project description:Vibrio species represent one of the most diverse genera of marine bacteria known for their ubiquitous presence in natural aquatic systems. Several members of this genus including Vibrio harveyi are receiving increasing attention lately because they are becoming a source of health problems, especially for some marine organisms widely used in sea food industry. To learn about adaptation changes triggered by V. harveyi during its long-term persistence at elevated temperatures, we studied adaptation of this marine bacterium in sea water microcosms at 30 oC that closely mimicks the upper limits of sea surface temperatures recorded around the globe.