Project description:Untargeted proteomics from a 5,000 km+ transect across the central Pacific Ocean from Hawaii to Tahiti. The expedition crossed multiple biogeochemical provinces, inlcuding the oligotrophic North Pacific Subtropical Gyre, the extremety of the Eastern Tropical North Pacific Oxygen Deficient Zone, and the relatively productive equatorial region associated with upwelling. This dataset focuses on the microbial fraction (0.2-3.0 micrometer filter size) and the microbial community dynamics across these biogeochemical provinces, from the surface oceance to the mesopelagic (1,250 m depth maximum).
Project description:Marine microbial communities are critical for biogeochemical cycles and the productivity of ocean ecosystems. Primary productivity, at the base of marine food webs, is constrained by nutrient availability in the surface ocean, and nutrient advection from deeper waters can fuel photosynthesis. In this study, we compared the transcriptional responses by surface microbial communities after experimental deep water mixing to the transcriptional patterns of in situ microbial communities collected with high-resolution automated sampling during a bloom in the North Pacific Subtropical Gyre. Transcriptional responses were assayed with the MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories) marine environmental microarray, which targets all three domains of life and viruses. The experiments showed that mixing of deep and surface waters substantially affects the transcription of photosystem and nutrient response genes among photosynthetic taxa within 24 hours, and that there are specific responses associated with the addition of deep water containing particles (organisms and detritus) compared to filtered deep water. In situ gene transcription was most similar to that in surface water experiments with deep water additions, showing that in situ populations were affected by mixing of nutrients at the six sampling sites. Together, these results show the value of targeted metatranscriptomes for assessing the physiological status of complex microbial communities.
Project description:Surface waters of the vast subtropical ocean gyres are poor in nutrients such as nitrogen (N), phosphorus (P), iron (Fe) and zinc (Zn). Ocean warming is predicted to intensify and expand these low nutrient gyres, but we have limited knowledge on how natural assemblages of marine microbes acquire nutrients. While detecting regions where the lack of N and/or Fe limits biological activity appears straightforward, it is problematic for P due to divergent results from different approaches used. Using natural zonal gradients in nutrient resources and biological activity, we investigated the nutrient acquisition strategies of Prochlorococcus and Synechococcus, with a specific focus on phosphorus since Fe and Zn may constrain the activity of the metalloenzyme, alkaline phosphatase, used by microbes to access dissolved organic phosphorus (DOP) when phosphate is scarce. Analyses of proteins indicative of nutrient acquisition and stress, termed ‘biomarkers’ alongside high-resolution biogeochemical measurements and nutrient bioassays concur on more intense phosphorus limitation in the western compared to the eastern subtropical Atlantic. However, we found sparse evidence of trace metal control of alkaline phosphatase by Fe or Zn or cobalt. Instead, zonal gradients as well as the bioassays involving the addition of Fe, Zn and DOP stimulated different responses in protein production in Prochlorococcus and Synechococcus, implying these picocyanobacteria may have different biomarkers indicative of nutrient stress, which has implications for the interpretation of trends in protein, as well as different strategies to acquire essential nutrients. The divergence in acquisition strategies alongside the asynchronous zonal gradients in Prochlorococcus and Synechococcus in the subtropical North Atlantic are likely driven by other processes such as nitrogen fixation, atmospheric and upwelled delivery of nutrients and competition for resources.
2025-12-10 | PXD054252 | Pride
Project description:microbial assemblages in the western subtropical Pacific Ocean
Project description:The levels of chlorophyll a and nutrient concentrations in the surface waters of the western subtropical Pacific Ocean are among the lowest globally. In addition, our knowledge of basin-scale diversity and biogeography of microbial communities in this vast extremely oligotrophic environment is still rather limited. Here, high-throughput sequencing was used to examine the biodiversity and biogeography of abundant and rare microbial assemblages throughout the water column from the surface to a depth of 3,000 m across a horizontal distance of 1,100 km in the western Pacific Ocean. Microbial alpha diversity in the 200-m layer was higher than at other depths, with Gammaproteobacteria, Alphaproteobacteria, and Clostridia as the dominant classes in all samples. Distinctly vertical distributions within the microbial communities were revealed, with no difference horizontally. Some microbes exhibited depth stratification. For example, the relative abundances of Cyanobacteria and Alphaproteobacteria decreased with depth, while Nitrososphaeria, Actinobacteria, and Gammaproteobacteria increased with depth in the aphotic layers. Furthermore, we found that environmental (selective process) and spatial (neutral process) factors had different effects on abundant and rare taxa. Geographical distance showed little effect on the dispersal of all and abundant taxa, while statistically significant distance-decay relationships were observed among the rare taxa. Temperature and chlorophyll a were strongly associated with all, abundant, and rare taxa in the photic layers, while total inorganic nitrogen was recognized as the crucial factor in the aphotic layers. Variance partitioning analysis indicated that environmental selection played a relatively important role in shaping all and abundant taxa, while the variation in rare taxa explained by environmental and spatial processes was relatively low, as more than 70% of the variation remained unexplained. This study provides novel knowledge related to microbial community diversity in the western subtropical Pacific Ocean, and the analyzes biogeographical patterns among abundant and rare taxa.
Project description:Global metaproteomic analyses of microbial biomass from the upper water column of the Central Pacific Ocean. This dataset was used as a discovery dataset to identify peptide biomarkers for cyanobacterial populations for use in targeted metaproteomic calibrated multiple reaction monitoring (MRM) analyses published in in Saito et al., 2014 and 2015. Saito, M. A., McIlvin, M. R., Moran, D. M., Goepfert, T. J., DiTullio, G. R., Post, A. F., and Lamborg, C. H.: Multiple nutrient stresses at intersecting Pacific Ocean biomes detected by protein biomarkers, Science, 345, 1173-1177, 2014. Saito, M. A., Dorsk, A., Post, A. F., McIlvin, M., Rappé, M. S., DiTullio, G., and Moran, D.: Needles in the Blue Sea: Sub‐Species Specificity in Targeted Protein Biomarker Analyses Within the Vast Oceanic Microbial Metaproteome, PROTEOMICS, 15, 3521-3531, 2015.
Project description:The diazotroph Trichodesmium is an important contributor to marine dinitrogen (N2) fixation, supplying so-called new N to phytoplankton in typically N-limited ocean regions. Identifying how iron (Fe) and phosphorus (P) influence Trichodesmium activity and biogeography is an ongoing area of study, where predicting patterns of resource stress is complicated in part by the uncertain bioavailability of organically complexed Fe and P. Here, a comparison of 26 metaproteomes from picked Trichodesmium colonies identified significantly different patterns between three ocean regions: the western tropical South Pacific, the western North Atlantic, and the North Pacific Subtropical Gyre. Trichodesmium metaproteomes across these regions significantly differed in KEGG submodule signals, and vector fitting showed that dissolved Fe, phosphate, and temperature significantly correlated with regional proteome patterns. Populations in the western tropical South Pacific appeared to modulate their proteomes in response to both Fe and P stress, including a comparatively low relative abundance of the N2 fixation marker protein, NifH. Significant increases in the relative abundance of both Fe and P stress marker proteins previously validated in culture studies suggested that Trichodesmium populations in the western North Atlantic and North Pacific were P-stressed and Fe-stressed, respectively. These patterns recapitulate established regional serial and co-limitation patterns of resource stress on phytoplankton communities. Evaluating community stress patterns may therefore predict resource controls on diazotroph biogeography. These data highlight how Trichodesmium modulates its metabolism in the field and provide an opportunity to more accurately constrain controls on Trichodesmium biogeography and N2 fixation.