Curated and harmonized gut microbiome 16S rRNA amplicon data from dietary fiber intervention studies in humans

Next generation amplicon sequencing has created a plethora of data from human microbiomes. The accessibility to this scientific data and its corresponding metadata is important for its reuse, to allow for new discoveries, verification of published results, and serving as path for reproducibility. Dietary fiber consumption has been associated with a variety of health benefits that are thought to be mediated by gut microbiota. To enable direct comparisons of the response of the gut microbiome to fiber, we obtained 16S rRNA sequencing data and its corresponding metadata from 11 fiber intervention studies for a total of 2,368 samples. We provide curated and pre-processed genetic data and common metadata for comparison across the different studies

Curated and Harmonized Gut Microbiome 16S rRNA Amplicon Data From Dietary Fiber Intervention Studies in Humans

Next generation amplicon sequencing has created a plethora of data from human microbiomes. The accessibility to this scientific data and its corresponding metadata is important for its reuse, to allow for new discoveries, verification of published results, and serving as path for reproducibility. Dietary fiber consumption has been associated with a variety of health benefits that are thought to be mediated by gut microbiota. To enable direct comparisons of the response of the gut microbiome to fiber, we obtained 16S rRNA sequencing data and its corresponding metadata from 11 fiber intervention studies for a total of 2,368 samples. We provide curated and pre-processed genetic data and common metadata for comparison across the different studies

Modeled Chl:C ratio and derived estimates of phytoplankton carbon biomass and its contribution to total particulate organic carbon in the global surface ocean

Chlorophyll (Chl) is a distinctive component of autotrophic organisms, often used as an indicator of phytoplankton biomass in the ocean. However, assessment of phytoplankton biomass from Chl relies on the accurate estimation of the Chl:carbon(C) ratio. Here we present global patterns of Chl:C ratios in the surface ocean obtained from a phytoplankton growth model that accounts for the optimal acclimation of phytoplankton to ambient nutrient, light, and temperature conditions. The model agrees largely with observed/expected global patterns of Chl:C. Combining our Chl:C estimates with satellite Chl and particulate organic carbon (POC), we infer phytoplankton C concentration in the surface ocean and its contribution to the total POC pool. Our results suggest that the portion of POC corresponding to living phytoplankton is higher in subtropical latitudes and less productive regions (∼30–70%) and decreases to ∼10–30% toward high latitudes and productive regions. An important caveat of our model is the lack of iron limiting effects on phytoplankton physiology. Comparison of our predicted phytoplankton biomass with an independent estimate of total POC reveals a positive correlation between nitrate concentrations and nonphotosynthetic POC in the surface ocean. This correlation disappears when a constant Chl:C is applied. Our analysis is not constrained by assumptions of constant Chl:C or phytoplankton:POC ratio, providing a novel independent analysis of phytoplankton biomass in the surface ocean. These results highlight the importance of accounting for the variability in Chl:C and its application in distinguishing the autotrophic and heterotrophic components in the assemblage of the marine plankton ecosystem

Global patterns of phytoplankton nutrient and light colimitation inferred from an optimality-based model

The widely used concept of constant ”Redfield” phytoplankton stoichiometry is often applied for estimating which nutrient limits phytoplankton growth in the surface ocean. Culture experiments, in contrast, show strong relations between growth conditions and cellular stoichiometry with often substantial deviations from Redfield stoichiometry. Here we investigate to what extent both views agree by analyzing remote sensing and in situ data with an optimality-based model of nondiazotrophic phytoplankton growth in order to infer seasonally varying patterns of colimitation by light, nitrogen (N), and phosphorus (P) in the global ocean. Our combined model-data analysis suggests strong N and N-P colimitation in the tropical ocean, seasonal light, and N-P colimitation in the Northern Hemisphere, and strong light limitation only during winter in the Southern Ocean. The eastern equatorial Pacific appears as the only ocean area that is essentially not limited by N, P, or light. Even though our optimality-based approach specifically accounts for flexible stoichiometry, inferred patterns of N and P limitation are to some extent consistent with those obtained from an analysis of surface inorganic nutrients with respect to the Redfield N:P ratio. Iron is not part of our analysis, implying that we cannot accurately predict N cell quotas in high-nutrient, low-chlorophyll regions. Elsewhere, we do not expect a major effect of iron on the relative distribution of N, P, and light colimitation areas. The relative importance of N, P, and light in limiting phytoplankton growth diagnosed here by combining observations and an optimal growth model provides a useful constraint for models used to predict future marine biological production under changing environmental conditions

Interactions between growth-dependent changes in cell size, nutrient supply and cellular elemental stoichiometry of marine Synechococcus

The factors that control elemental ratios within phytoplankton, like carbon:nitrogen:phosphorus (C:N:P), are key to biogeochemical cycles. Previous studies have identified relationships between nutrient-limited growth and elemental ratios in large eukaryotes, but little is known about these interactions in small marine phytoplankton like the globally important Cyanobacteria. To improve our understanding of these interactions in picophytoplankton, we asked how cellular elemental stoichiometry varies as a function of steady-state, N- and P-limited growth in laboratory chemostat cultures of Synechococcus WH8102. By combining empirical data and theoretical modeling, we identified a previously unrecognized factor (growth-dependent variability in cell size) that controls the relationship between nutrient-limited growth and cellular elemental stoichiometry. To predict the cellular elemental stoichiometry of phytoplankton, previous theoretical models rely on the traditional Droop model, which purports that the acquisition of a single limiting nutrient suffices to explain the relationship between a cellular nutrient quota and growth rate. Our study, however, indicates that growth-dependent changes in cell size have an important role in regulating cell nutrient quotas. This key ingredient, along with nutrient-uptake protein regulation, enables our model to predict the cellular elemental stoichiometry of Synechococcus across a range of nutrient-limited conditions. Our analysis also adds to the growth rate hypothesis, suggesting that P-rich biomolecules other than nucleic acids are important drivers of stoichiometric variability in Synechococcus. Lastly, by comparing our data with field observations, our study has important ecological relevance as it provides a framework for understanding and predicting elemental ratios in ocean regions where small phytoplankton like Synechococcus dominates

ANALISIS PENGARUH LIKUIDITAS, LEVERAGE, DAN PROFITABILITAS TERHADAP LABA

Penelitian ini bertujuan untuk mengetahui seberapa besar pengaruh likuiditas, leverage dan profitabilitas terhadap laba yang dimiliki oleh PT.Gajah Tunggal Tbk. selama periode 1997-2008.Pengujian hipotesis ini menggunakan analisis regresi linier berganda, Uji F, dan Uji t.Hasil dari penelitian ini adalah bahwa likuiditas, leverage dan profitabilitas secara bersama-sama memiliki pengaruh terhadap laba sedangkan bila dilihat dari uji t yang memiliki pengaruh dominant terhadap laba yang diperoleh PT.Gajah Tunggal Tbk. selama periode 1997-2008 adalah profitabilitas dengan menggunakan rasio NPM (Net Profit Margin)

Effects of African dust deposition on phytoplankton in the western tropical Atlantic Ocean off Barbados

Bioassay incubation experiments conducted with nutrients and local atmospheric aerosol amendments indicate that phosphorus (P) availability limited phytoplankton growth in the low-nutrient low-chlorophyll (LNLC) ocean off Barbados. Atmospheric deposition provides a relatively large influx of new nutrients and trace metals to the surface ocean in this region in comparison to other nutrient sources. However, the impact on native phytoplankton is muted due to the high ratio of nitrogen (N) to P (NO3:SRP > 40) and the low P solubility of these aerosols. Atmospheric deposition induces P limitation in this LNLC region by adding more N and iron (Fe) relative to P. This favors the growth of Prochlorococcus, a genus characterized by low P requirements and highly efficient P acquisition mechanisms. A global three-dimensional marine ecosystem model that includes species-specific phytoplankton elemental quotas/stoichiometry and the atmospheric deposition of N, P, and Fe supports this conclusion. Future increases in aerosol N loading may therefore influence phytoplankton community structure in other LNLC areas, thereby affecting the biological pump and associated carbon sequestration