Abstract:
This dataset was collected from two laboratory flask experiments (short term and long term) using natural seawater collected from Galveston Bay, Texas (29.31305°N; 94.81666°W) for triplicate treatments for control and oil (4ppm). Each experiment was run in parallel with radioactive control and radioactive oil (4ppm) triplicate treatments. Included are measurements of the interactions of bacteria (3H-Leucine) and phytoplankton (sodium bicarbonate, NaH14CO3) by tracking the exchange of radio-labeled metabolites between different size fractions (3 um for phytoplankton and associated phycosphere; 0.2 um for free-living bacteria; 3 kDa for extracellular polymeric substances (EPS) colloidal material).
Associated datasets: UDI:R6.x807.000:0023 (DOI 10.7266/n7-n5p6-p566); UDI: R6.x807.000:0024 (DOI 10.7266/n7-321d-vj38); UDI:R6.x807.000:0029 (DOI 10.7266/n7-sj41-vw18); and UDI: R6.x807.000:0030.
Suggested Citation:
Kamalanathan, Manoj, Kathy Schwehr, Christian Taylor, Charles Bergen, Nicole Patterson, Noah Claflin, Peter Sanstchi and Antonietta Quigg. 2020. Microcosm: Flask experiment of phytoplankton-bacteria interaction in a natural community using control and WAF treatments; radiolabeling experiment; activities of bacteria, phytoplankton, oil. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-321d-vj38
Purpose:
To track the characterization changes of extracellular polymeric substances (EPS), this experiment was run in parallel without radio-labelled tracers and compliments the measurements made in a parallel experiment conducted using radio-tracers.
Methods:
Seawater, salinity 28, was collected from the Galveston Bay, Texas (29.31305°N; 94.81666°W) and aliquoted into 2 non-radioactive treatments in triplicate where 1) seawater with no additions and 2) seawater with 4 ppm Macondo surrogate oil. The concentration of oil (in Oil A, Oil B, and Oil C) at t = 0 was 400 microliters of oil/liter of seawater. The experiment was run with a 12:12 light dark cycle in a phytoplankton culture room with controlled temperature at 22°C for 4 days (January 22, 2019 through January 25, 2019). From these 2 treatments, daily time series samples were taken on July 18, 2019. These were used to determine the phytoplankton and bacteria assemblages using 18s and 16S rRNA genes sequencing, particulate C/N, DOC, DTN, and the protein and polysaccharide (neutral sugar and uronic acid) content of the extracellular polymeric substances (EPS), exoenzyme activity, cell counts, and for fluorescent microscope work.
Phytoplankton physiological indicators were tracked, including chlorophyll a, Fv/Fm (photosynthesis efficiency), relative electron transfer rates (rate of photosynthesis), sigma (size of the phytoplankton antennae that harvest light). The seawater was also aliquoted to run radiolabeled incubations in parallel to the non-radioactive treatments. These treatments, also in triplicate, were all inoculated with sodium bicarbonate (NaH14CO3) and an amino acid (3H-Leucine). The treatments were seawater with 1) NaH14CO3 and 3H-Leucine, 2) NaH14CO3 and 3H-Leucine with 4 ppm Macondo surrogate oil. The experimental design is shown in Figure 2. Radiolabeled chemicals were obtained from American Radiolabeled Chemicals, ARC. The NaH14CO3 (100 uCi/0.1 mL, 57.5 mCi/mM) was inoculated into the samples at an activity of 20 uCi/L. The 3H-Leucine (1 mCi/1 mL, 54.1 Ci/mM) activity was 50 uCi/L. The activities were counted on a Beckman-Coulter LS-6500 liquid scintillation counter using a dual channel program. Sample activities were corrected for isotope dilution and reagent quenching by adding a known activity spike to the same reagent matrix as the samples. The radiolabeled samples were taken daily from the 2 treatments and filtered in a series. A 10 mL aliquot was passed through a 3 µm filter (cellulose acetate, Sterlitech) to capture primarily phytoplankton, then the filtrate was passed through a 0.2 µm filter (cellulose acetate, Sterlitech) to capture primarily free living bacteria. The remaining 0.2 µm filtrate was then ultrafiltered through a 3 kDa membrane (ThermoFisher EMD Amicon-15 centrifugal device) for the colloidal EPS fraction, and diafiltered against ultrapure 18.2 MΩ–cm water to remove salts. The activities for 14C and 3H for each time sample for each fraction (3 µm filter, 0.2 µm filter, colloidal EPS <0.2 µm and >3kDa, and the 3kDa permeate) were counted for each day of the 4 day experiment for the long term experiment, and for selected hour intervals for the short term experiment.
The long term experiment was sampled daily for 4 days from January 22, 2019 through January 25, 2019.
The short term experiment was sampled for selected hourly intervals (0, 1, 2, 3, 4, 8) on July 18, 2019.
View Metadata