1. Algae cultured w/ f/2 medium and growth curve monitored Cultures were centrifuged & filtered through a 0.45 um pc filter Diafiltered through 1kDa ultrafiltration membrane Desalted Freeze Dried Chemical characterization Isolation and Comparison of Exopolymeric Substances (EPS) From Dominant Phytoplankton Species In The Gulf of Mexico Benjamin J. Kennady, Chia-Ying Chuang, Yi-Fang Ho, Kathleen A. Schwehr, and Peter H. Santschi Laboratory for Oceanographic and Environmental Research (LOER), Undergraduate-Departments of Oceanography and Marine Sciences, Texas A&M University APPROACHES RESULTS & DISCUSSION REFERENCES This work was funded by grant from the National Science Foundation (OCE-0961057). ACKNOWLEDGEMENT Figure 2. Conceptional flow diagram detailing the EPS extraction and presented work. Figure 2. ATR-FTIR spectra of EPS. Interest in EPS has recently been increasing as they have a great impact on many geochemical processes, including prediction of POC flux, trace element, nanoparticle, and radionuclide scavenging, as well as tracing different water masses. Amide I Amide II Polysaccharide Amide II Amide IPolysaccharide Table 2. ATR-FTIR content values of identified Amides and Polysaccharides Table 1. Data of growth rate and chemical analysis of EPS. Growth Curve ATR-FTIR CONCLUSION Xu, C., Santschi, P. H., Schwehr, K. A., Hung, C.-C., 2009. Optimized isolation procedure for obtaining strongly actinide binding exopolymeric substances (EPS) from two bacteria (Sagittula stellata and Pseudomonas flurorescens Biovar II). Bioresource Technology. 100, 6010-6021. Zhang, S. J.; Santschi, P. H., Application of cross-flow ultrafiltration for isolating exopolymeric substances from a marine diatom (Amphora sp.). Limnology and Oceanography-Methods 2009, 7, 419-429. OBJECTIVES Four phytoplankton species were chosen because of their dominance in the Gulf of Mexico. These species are Dunaliella tertiolecta, Synechococcus elongates, Emiliania huxleyi, and Phaeodactylum tricornutum. The growth curves of these algae were monitored using a Spectrophotometer at 750 nm. By monitoring the growth curve, the transitional phase for each algae culture was estimated so that the EPS could be collected under similar conditions. EPS was harvested through a series of filtration processes between the sizes of 0.45 μm and 1 Kda. These non-attached EPS were tested using ATR-FTIR, Spectrophotometry, and CHN/S elemental analyzer. Results will be used to determine and compare the total polysaccharides, proteins, and elemental contents of each phytoplankton species, thus allowing for a better understanding of the total EPS composition in the Gulf of Mexico. Figure 5. Comparison of composition using two different methods Emiliania huxleyiDunaliella tertiolecta Synechococcus elongates Phaeodactylum tricornutum Phaedactylum tricornutum w/o silica Figure 1. These images show the morphology of chosen phytoplankton species. 1.The growth rates determined by monitoring growth curve of different species of algae showed significant differences. EPS of each species of algae was harvested at its transitional phase (Fig. 2 & Table 1). Cyanobacterica, Synechococcus elongates, and diatom, Phaeodactylum tricornutum, showed almost twice of its growth rate than coccolithophores, Emiliania huxleyi, and green algae, Dunaliella tertiolecta. 2.Different relative amounts of functional groups, such as amides, and carbohydrates were observed on the ATR-FTIR spectra of those EPS (Fig. 4). 3.Chemical composition analysis data showed some differences compared with ATR-FTIR results (Fig. 5), suggesting that FTIR analysis is not a fully quantitative method. To better quantify chemical composition of EPS, spectrophotometric method is still necessary. 4.EPS harvested from algae cultures all showed higher polysaccharides content than its protein content, which is common as seen in dissolved EPS from previous studies. Figure 4. ATR-FTIR spetra of EPS INTRODUCTION Protein TCHO URA Spectrophotometry TOC TON Elemental analysisATR-FTIR Figure 3. Growth curves of cultured phytoplankton. These growth curves helped to predict the growth rate and can be used to determine the ideal time for EPS harvesting.