Abstract:
Both phytoplankton and bacteria secrete extracellular enzymes actively that help them degrade the complex molecules to provide them simple carbon (sugars) and nitrogen (amino acids) molecules that can be easily assimilated. This process supports bacterial growth on exopolymeric substances (EPS) and helps support their cell division. However, this process does not lead to depletion of EPS, as only a fraction is consumed by bacteria. Due to the sticky nature of the EPS, the newly formed bacteria will tend to adhere to the EPS, and this will lead to the eventual formation and increase in the size of aggregates. To test this, we added DCB (2,6-dichlorobenzonitrile; an inhibitor of polysaccharide production in diatoms) to Thalassiosira pseudonana in the presence and absence of oil. This dataset contains algal and bacterial growth in terms of enzyme assays, microbial cell counts, monosaccharide concentrations, and photosynthesis data at different WAF concentrations in terms of estimated oil equivalent (EOE), polycyclic aromatic hydrocarbons (PAHs), and alkanes. Other related microcosm datasets are available under GRIIDC UDIs R6.x807.000:0027 and R6.x807.000:0028.
Data Parameters and Units:
Folder “enzymes” contains the enzyme activity data for Lipase, Leucine amino-peptidase, Beta-glucosidase and Alkaline phosphatase. All the files contain the day and enzyme activity (units = nMol.hr-1) for the control, WAF, Control + DCB, WAF + DCB assays.
Folder “microbial cell counts” contains the cell counts (units = cells.mL-1) of algae (Thalassiosira pseudonana) and bacteria per day for the control, WAF, Control + DCB, WAF + DCB assays.
Folder “monosaccharides” contains the monosaccharides per cell (units = ng.cell-1) in time (final time point) data for the control, WAF, Control + DCB, WAF + DCB assays.
Folder ‘Oil data” contains the estimated oil equivalent (EOE; units=mg.L-1) per day for the control, WAF, Control + DCB, WAF + DCB assays; alkanes and PAHs (ng.mL-1) for the initial and final time point for the control, WAF, Control + DCB, WAF + DCB experiments.
Folder “photosynthesis data” contains absorption cross sectional area of PSII (units = Angstrom. quanta-1), maximum quantum yield of photosystem II (relative units), connectivity factor of photosystem II (relative units), chlorophyll-a (units = microg.mL), chlorophyll-a per cell (units = microg.cell-1), relative electron transport rates (units: micromol.electrons m2.s-1), rate of QA turnover (units = microseconds), light harvesting ability (units = micromol photons. m-2. sec-1) per day for all experiments (Control, WAF, Control + DCB and WAF + DCB).
Methods:
Thalassiosira pseudonana (CCMP 1335) was obtained from the National Center for Marine Algae and Microbiota (NCMA). The WAF was prepared by adding oil (400 µL.L-1) into sterile f/2 growth media and stirred overnight in the dark. T. pseudonana cultures were inoculated in control f/2 medium (6 × 1000 mL) and WAF medium (6 × 1000 mL) with approximately 2.6 × 104 cells mL−1. DCB solution prepared in Dimethyl sulfoxide (DMSO) was added to half of the both Control and WAF treatments (3 out of 6 × 1000 mL) to obtain a final concentration of 150 µM. T. pseudonana were incubated for 24-h prior to the addition of DCB to allow growth. Growth was monitored by daily cell counts measured by microscopy using an improved Neubauer hemocytometer. The PHYTOPAM was used to measure relative electron transport rates and light harvesting efficiency. The FIRe fluorometer system was used to measure maximum PSII quantum yield, functional absorption cross-section of PSII, connectivity factor defining the excitation energy transfer between individual photosynthetic units. Bacteria cell counts were measured using the fluorescent dye 4′,6-diamidino-2-phenylindole (DAPI) by the methods described by Sun et al. (2018). Activities of extracellular enzymes such as α- and β-glucosidase, alkaline phosphatase, leucine amino-peptidase, and lipase were measured on days 3, 5, 7 and 11 with the help of MUF and AMC tagged substrates using the methods described by Kamalanathan et al. (2018). Monosaccharides were determined for both intracellular and extracellular samples using the TPTZ method (Myklestad et al., 1997 with minor modification from Hung et al., 2001) with glucose as standard. Oil analysis was carried out on the very first and last days of the experiment using methods described in Bacosa et al. (2015) and Liu et al. (2016).
Provenance and Historical References:
Bacosa, H. P., Liu, Z., & Erdner, D. L. (2015). Natural sunlight shapes crude oil-degrading bacterial communities in Northern Gulf of Mexico surface waters. Frontiers in microbiology, 6, 1325.
Sun, L., Chiu, M.H., Xu, C., Lin, P., Schwehr, K.A., Bacosa, H., Kamalanathan, M., Quigg, A., Chin, W.C. and Santschi, P.H. (2018). The effects of sunlight on the composition of exopolymeric substances and subsequent aggregate formation during oil spills. Marine Chemistry.
Kamalanathan, M., Xu, C., Schwehr, K., Bretherton, L., Beaver, M., Doyle, S., Genzer, J., Hillhouse, J., Santschi, P.H. and Quigg, A. (2018). Extracellular enzyme activity profile in a chemically enhanced water accommodated fraction of surrogate oil: towards understanding microbial activities after the Deepwater Horizon oil spill. Frontiers in microbiology, 9, 798.
Myklestad, S. M., Skånøy, E., & Hestmann, S. (1997). A sensitive and rapid method for analysis of dissolved mono-and polysaccharides in seawater. Marine Chemistry, 56(3-4), 279-286.
Hung, C. C., & Santschi, P. H. (2001). Spectrophotometric determination of total uronic acids in seawater using cation-exchange separation and pre-concentration by lyophilization. Analytica Chimica Acta, 427(1), 111-117.
Liu, J., Bacosa, H. P., & Liu, Z. (2017). Potential environmental factors affecting oil-degrading bacterial populations in deep and surface waters of the northern Gulf of Mexico. Frontiers in microbiology, 7, 2131.
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