One-quarter of photosynthesis-derived carbon on Earth rapidly cycles through a set of short-lived seawater metabolites that are generated from the activities of marine phytoplankton, bacteria, ...grazers and viruses. Here we discuss the sources of microbial metabolites in the surface ocean, their roles in ecology and biogeochemistry, and approaches that can be used to analyse them from chemistry, biology, modelling and data science. Although microbial-derived metabolites account for only a minor fraction of the total reservoir of marine dissolved organic carbon, their flux and fate underpins the central role of the ocean in sustaining life on Earth.
Stormwater detention ponds are widely utilized as control structures to manage runoff during storm events. These ponds also represent biogeochemical hotspots, where carbon (C) and nutrients can be ...processed and buried in sediments. This study quantified C and nutrient nitrogen (N) and phosphorus (P) sources and burial rates in 14 stormwater detention ponds representative of typical residential development in coastal South Carolina. Bulk sediment accumulation was directly correlated with catchment impervious surface coverage (R² = 0.90) with sediment accumulation rates ranging from 0.06 to 0.50 cm y⁻¹. These rates of sediment accumulation and consequent pond volume loss were lower than anticipated based on maintenance guidelines provided by the State. N-alkanes were used as biomarkers of sediment source; the derived terrestrial aquatic ratio (TARHC) index was strongly correlated with sediment accumulation rate (R² = 0.71) which, in conjunction with high C/N ratios (16–33), suggests that terrestrial biomass drives this sediment accumulation, with relatively minimal contributions from algal derived material. This is counter to expectations that were based on the high algal productivity generally observed in stormwater ponds and previous studies of natural lakes. Sediment C and nutrient concentrations were consistent among ponds, such that differences in burial rates were a simple function of bulk sediment accumulation rate. These burial rates (C: 8.7–161 g m⁻² y⁻¹, N: 0.65–6.4 g m⁻² y⁻¹, P: 0.238–4.13 g m⁻² y⁻¹) were similar to those observed in natural lake systems, but lower than those observed in reservoirs or impoundments. Though individual ponds were small in area (930–41,000 m²), they are regionally abundant and, when mean burial rates are extrapolated to the regional scale (≈ 21,000 ponds), ultimately sequester 2.0 × 10⁹ g C y⁻¹, 9.5 × 10⁷ g N y⁻¹, and 3.7 × 10⁷ g P y⁻¹ in the coastal region of South Carolina alone. Stormwater ponds represent a relatively new but increasingly significant feature of the coastal landscape and, thus, are a key component in understanding how urbanization alters the transport and transformations of C and nutrients between terrestrial uplands and downstream receiving waters.
Metabolite exchange within marine microbial communities transfers carbon and other major elements through global cycles and forms the basis of microbial interactions. Yet lack of gene annotations and ...concern about the quality of existing ones remain major impediments to revealing currencies of carbon flux. We employed an arrayed mutant library of the marine bacterium Ruegeria pomeroyi DSS-3 to experimentally annotate substrates of organic compound transporter systems, using mutant growth and compound drawdown analyses to link transporters to their cognate substrates. Mutant experiments verified substrates for thirteen R. pomeroyi transporters. Four were previously hypothesized based on gene expression data (taurine, glucose/xylose, isethionate, and cadaverine/putrescine/spermidine); five were previously hypothesized based on homology to experimentally annotated transporters in other bacteria (citrate, glycerol, N-acetylglucosamine, fumarate/malate/succinate, and dimethylsulfoniopropionate); and four had no previous annotations (thymidine, carnitine, cysteate, and 3-hydroxybutyrate). These bring the total number of experimentally-verified organic carbon influx transporters to 18 of 126 in the R. pomeroyi genome. In a longitudinal study of a coastal phytoplankton bloom, expression patterns of the experimentally annotated transporters linked them to different stages of the bloom, and also led to the hypothesis that citrate and 3-hydroxybutyrate were among the most highly available bacterial substrates. Improved functional annotation of the gatekeepers of organic carbon uptake is critical for deciphering carbon flux and fate in microbial ecosystems.
The Ocean's labile DOC supply chain Moran, Mary Ann; Ferrer‐González, Frank X.; Fu, He ...
Limnology and oceanography,
20/May , Letnik:
67, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Microbes of the surface ocean release, consume, and exchange labile metabolites at time scales of minutes to days. The details of this important step in the global carbon cycle remain poorly ...resolved, largely due to the methodological challenges of studying a diverse pool of metabolites that are produced and consumed nearly simultaneously. In this perspective, a new compilation of published data builds on previous studies to obtain an updated estimate of the fraction of marine net primary production that passes through the labile dissolved organic carbon (DOC) pool. In agreement with previous studies, our data mining and modeling approaches hypothesize that about half of ocean net primary production is processed through the labile DOC pool. The fractional contributions from three major sources are estimated at 0.4 for living phytoplankton, 0.4 for dead and dying phytoplankton, and 0.2 for heterotrophic microbes and mesoplankton.
We demonstrate and evaluate an on-demand source of single itinerant microwave photons. Photons are generated using a highly coherent, fixed-frequency qubit-cavity system, and a protocol where the ...microwave control field is far detuned from the photon emission frequency. By using a Josephson parametric amplifier (JPA), we perform efficient single-quadrature detection of the state emerging from the cavity. We characterize the imperfections of the photon generation and detection, including detection inefficiency and state infidelity caused by measurement backaction over a range of JPA gains from 17 to 33 dB. We observe that both detection efficiency and undesirable backaction increase with JPA gain. We find that the density matrix has its maximum single photon component \(\rho_{11} = 0.36 \pm 0.01\) at 29 dB JPA gain. At this gain, backaction of the JPA creates cavity photon number fluctuations that we model as a thermal distribution with an average photon number \(\bar{n} = 0.041 \pm 0.003\).
Abstract The effect of increased total knee arthroplasty (TKA) surgical volume on the incidence of knee complications within a single surgeon's practice was determined. Data were collected ...prospectively on 600 primary TKAs. Major complications required knee reoperation. Minor complications were wound concerns requiring increased surveillance or oral antibiotics. Twelve major (2.0%) and 40 minor (6.7%) complications occurred at minimum 2-year follow-up. Surgical volume increased from 57 to 150 procedures per 6 months through the course of the study. Multivariate analysis determined that increased surgical volume was associated with lower rates of both major and minor complications, adjusted odds ratio 0.62 (95% confidence interval CI, 0.40-0.96) and 0.56 (95% CI, 0.43-0.73), respectively. For each additional 50 procedures performed within a 6-month interval, major complications were reduced by 38% ( P = .03), and minor complications were reduced by 44% ( P < .0001). All complications were significantly decreased when the surgeon was performing 112 ± 44 TKAs compared with 85 ± 49 TKAs per 6-month interval.
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