Abstract:
We examine particle size after sunlight irradiation in three natural seawaters, eight marine microbial exopolymeric substance solutions, and five standard biopolymer solutions. We find that protein-containing dissolved organic matter (DOM) polymers and reactive oxygen species play important roles in aggregate formation during irradiation. The photo-flocculation of DOM provides new insights into polymer assembly, bioavailability of DOM in the global carbon and nitrogen cycles.
Suggested Citation:
Luni Sun, Meng-Hsuen Chiu, Wei-Chun Chin, Peter H. Santschi. 2018. Light induced aggregation of protein-containing compounds. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7DJ5D49
Data Parameters and Units:
This dataset contains laboratory measurements of carbohydrate, protein, uronic acid, total organic carbon (TOC), total organic nitrogen (TN), particulate carbon, particulate nitrogen. Data Parameters and Units: EPS= exopolymeric substance TOC= total organic carbon; TN= total nitrogen; DI= ultrapure water; ASW= artificial seawater; GOM= gulf of Mexico; SF= San Francisco; ss1= S. stellate 1; ss2= S. stellate 2; amp= Amphora sp.; tp1= Thalassiosira pseudonana 1; tp2= Thalassiosira pseudonana 2; pg= Phaeocystis globosa; pt= P. tricornutum; GOMEPS= EPS obtained from GOM seawater; URA= uronic acid; Initial= original sample; Dark= no exposure; Light= under irradiation; Protein concentration: mg/L Neutral sugar concentration: mg/L URA concentration: mg/L TOC, TN: ppm absorbance: No unit The number 1,2,3.. means replicate number Particle size: nm carbon: mg nitrogen: mg DLS= dynamic light scattering
Methods:
Files carbohydrate concentration.csv, protein concentration.csv, and URA concentration.csv report the concentrations of carbohydrates, proteins and uronic acid from EPS obtained from bacteria that were then used in experiments. EPS fro mpg, GOMEPS, SF and biopolymers were not analyzed for carbohydrates, proteins or uronic acid. Bovine serum albumin (BSA) was used as protein standard, glucose was used as carbohydrate standard, and glucuronic acid was used as uronic standard. The file CHN.csv was measured only for Gulf of Mexico Seawater in both light and dark conditions. In the file toc and tn.csv the sample labelled "ss" should be "ss1" and the sample labelled "tp" should be "tp1". The data in the file toc and tn.csv are from the ASW treatment only. The GOM seawater was collected from NOAA National Marine Fisheries Laboratory (Galveston, TX) and the SF seawater was collected at Torpedo Wharf of San Francisco Bay (San Francisco, CA). EPS were obtained from bacteria S. stellata and GOM, and four phytoplankton Amphora sp., Thalassiosira Pseudonana, Phaeocystis Globose, and P. tricornutum followed the procedures described in previous studies. The natural EPS and standard polymers Rubsico, fetuin, dextran, alginic acid, and lipopolysaccharide were dissolved in DI water or ASW to a final concentration of 2 mg/L. The seawaters, EPS, and standard polymers were filtered through a 0.2 μm polycarbonate filter (Millipore) to remove any particles before irradiation. All samples were irradiated in 250 mL quartz flasks in a water bath by circulating water of temperature 22±1 ºC around the flasks. One set of flasks were wrapped with foil to be used as dark control. After 1 h, all samples were harvested for further analysis. Neutral sugars were determined by the anthrone method, URA were determined by the phenyl phenol method, and proteins were determined by the Lowry Protein Assay Kit (Pierce, 23240, USA). Samples were measured absorbance in the well plate, the data was collected every 1 nm wavelength. TOC and TN of the filtrate were measured on a Shimadzu TOC-L analyzer. The sample was acidified to pH <3. The filtrate was measured on the instrument. Particulate organic carbon and particulate nitrogen in the GOM seawater were measured by filtering the samples through GF/F filter. The materials collected on the filter were measured using a Perkin Elmer CHNS/O 2400 analyzer. Selected samples were measured by dynamics laser scattering (DLS) (Brookhaven Instruments, NY, USA).
Instruments:
absorbance: Biotech-Epoch UV-vis spectrometer fluorescence: Shimadzu RF-5301PC epifluorescence microscope: Leica DM 2000 LED epifluorescence microscope equipped with an A4 filter cube TOC, TN: Shimadzu TOC-L analyzer Particulate organic carbon and particulate nitrogen: Perkin Elmer CHNS/O 2400 analyzer. DLS: Brookhaven BI 9000AT auto correlator (Brookhaven Instruments, NY, USA)
Error Analysis:
TOC, TN: automatic by instrument, coefficient of variation set to 3% or less. Absorbance for protein and carbohydrate concentration: errors were calculated from triplicates
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