Contributors | Affiliation | Role |
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Arnosti, Carol | University of North Carolina at Chapel Hill (UNC-Chapel Hill) | Principal Investigator |
Copley, Nancy | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
This dataset includes peptidase hydrolysis rates from sediments to measure microbial enzyme activities. Links to archived CTD data are also provided. Five substrates linked to a 7-amido-4-methyl coumarin (MCA) fluorophore, one amino acid – leucine – and four oligopeptides – the chymotrypsin substrates alanine-alanine-phenylalanine (AAF) and alanine-alanine-proline-phenylalanine (AAPF), and the trypsin substrates glutamine-alanine-arginine (QAR) and glutamic acid-gylcine-arginine (EGR) – were used to measure exo- and endo-acting peptidase activities, respectively.
Surficial sediments were collected using a multi-corer.
Five substrates linked to a 7-amido-4-methyl coumarin (MCA) fluorophore, one amino acid – leucine – and four oligopeptides – the chymotrypsin substrates alanine-alanine-phenylalanine (AAF) and alanine-alanine-proline-phenylalanine (AAPF), and the trypsin substrates glutamine-alanine-arginine (QAR) and glutamic acid-gylcine-arginine (EGR) – were used to measure exo- and endo-acting peptidase activities, respectively. Hydrolysis rates of the substrates were measured as an increase in fluorescence as the fluorophore was hydrolyzed from the substrate over time [as in Hoppe, 1993; Obayashi and Suzuki, 2005]. For sediment measurements, peptidase activities were measured in a 1:2 (vol: vol) sediment: autoclaved seawater slurry. 100 micromolar concentrations of substrate were added to triplicate live and single autoclaved killed control incubations. 2 ml of slurry was centrifuged at each timepoint (0, 1h ,2h, and 4 h), filtered, and diluted with 1 ml borate buffer; fluorescence was measured in a 4 ml cuvette. Hydrolysis rates were calculated from the rate of increase of fluorescence in the incubation over time relative to a set of standards of known concentration of fluorophore.
All incubations were conducted at 0 C in the dark.
BCO-DMO Processing Notes:
- added conventional header with dataset name, PI name, version date
- reduced decimal precision of rate columns from 9 to 6 places
File |
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ARK27-3_sed_MCA_joined.csv (Comma Separated Values (.csv), 10.87 KB) MD5:50e56c1aba72e92bc773d3c6e0f5c724 Primary data file for dataset ID 743018 |
Parameter | Description | Units |
station_no | refers to station number for cruise | unitless |
depth_no | sequence of depths sampled (1 is surface; higher numbers at greater depths) | unitless |
depth_m | actual depth at which water collected | meters |
cast_no | cast number (refers to cast of CTD/Niskin bottles on cruise) | unitless |
ISO_DateTime_UTC | date and time in ISO format (yyyy-mm-ddTHH:MM:SS | unitless |
Latitude | latitude; north is positive | decimal degreed |
Longitude | longitude; east is postivie | decimal degreed |
substrate | substrates for measurement of enzymatic activities. ara:arabinogalactan; chn:chondroitin sulfate; fuc:fucoidan; lam:laminarin ; pul:pullulan; xyl:xylan | unitless |
timepoint | sampling point post-incubation | unitless |
time_elapsed_hr | incubation time | hours |
rep1_rate | replicate 1 hydrolysis rate | nanomoles/liter/hour (nmol L-1 h-1) |
rep2_rate | replicate 2 hydrolysis rate | nanomoles/liter/hour (nmol L-1 h-1) |
rep3_rate | replicate 3 hydrolysis rate | nanomoles/liter/hour (nmol L-1 h-1) |
average | average of hydrolysis rates | nanomoles/liter/hour (nmol L-1 h-1) |
std_dev | std deviation of hydrolysis rates | nanomoles/liter/hour (nmol L-1 h-1) |
comments | url of CTD data in Pangaea database | unitless |
Dataset-specific Instrument Name | |
Generic Instrument Name | Centrifuge |
Generic Instrument Description | A machine with a rapidly rotating container that applies centrifugal force to its contents, typically to separate fluids of different densities (e.g., cream from milk) or liquids from solids. |
Dataset-specific Instrument Name | |
Generic Instrument Name | CTD - profiler |
Generic Instrument Description | The Conductivity, Temperature, Depth (CTD) unit is an integrated instrument package designed to measure the conductivity, temperature, and pressure (depth) of the water column. The instrument is lowered via cable through the water column. It permits scientists to observe the physical properties in real-time via a conducting cable, which is typically connected to a CTD to a deck unit and computer on a ship. The CTD is often configured with additional optional sensors including fluorometers, transmissometers and/or radiometers. It is often combined with a Rosette of water sampling bottles (e.g. Niskin, GO-FLO) for collecting discrete water samples during the cast.
This term applies to profiling CTDs. For fixed CTDs, see https://www.bco-dmo.org/instrument/869934. |
Dataset-specific Instrument Name | mini fluorometer |
Generic Instrument Name | Fluorometer |
Generic Instrument Description | A fluorometer or fluorimeter is a device used to measure parameters of fluorescence: its intensity and wavelength distribution of emission spectrum after excitation by a certain spectrum of light. The instrument is designed to measure the amount of stimulated electromagnetic radiation produced by pulses of electromagnetic radiation emitted into a water sample or in situ. |
Dataset-specific Instrument Name | |
Generic Instrument Name | Multi Corer |
Generic Instrument Description | The Multi Corer is a benthic coring device used to collect multiple, simultaneous, undisturbed sediment/water samples from the seafloor. Multiple coring tubes with varying sampling capacity depending on tube dimensions are mounted in a frame designed to sample the deep ocean seafloor. For more information, see Barnett et al. (1984) in Oceanologica Acta, 7, pp. 399-408. |
Website | |
Platform | R/V Polarstern |
Start Date | 2012-08-02 |
End Date | 2012-10-08 |
Description | Project: Latitudinal and depth-related contrasts in enzymatic capabilities of pelagic microbial communities: Predictable patterns in the ocean?
For other files related to this cruise, see https://www.pangaea.de/?q=ARK+XXVII%2F3. |
NSF Award Abstract:
Heterotrophic microbial communities are key players in the marine carbon cycle, transforming and respiring organic carbon, regenerating nutrients, and acting as the final filter in sediments through which organic matter passes before long-term burial. Microbially-driven carbon cycling in the ocean profoundly affects the global carbon cycle, but key factors determining rates and locations of organic matter remineralization are unclear. In this study, researchers from the University of North Carolina at Chapel Hill will investigate the ability of pelagic microbial communities to initiate the remineralization of polysaccharides and proteins, which together constitute a major pool of organic matter in the ocean. Results from this study will be predictive on a large scale regarding the nature of the microbial response to organic matter input, and will provide a mechanistic framework for interpreting organic matter reactivity in the ocean.
Broader Impacts: This study will provide scientific training for undergraduate and graduate students from underrepresented groups. The project will also involve German colleagues, thus strengthening international scientific collaboration.
Funding Source | Award |
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NSF Division of Ocean Sciences (NSF OCE) |