Isolation and comparison of exopolymeric substances (EPS) from five dominant phytoplankton species in the Gulf of Mexico

Abstract

Interest in EPS has recently been increasing as they have a great impact on many of geochemical processes, including prediction of POC flux, trace element, nanoparticle, and radionuclide scavenging, and tracing different water masses. EPS, released from marine micro-organisms are composed of polysaccharides and proteins, . Thus, there is a great need for these compounds to be characterized. Five phytoplankton species were chosen because of their dominance in the Gulf of Mexico. These species are Dunaliella tertiolecta, Thalassiosira pseudonana, 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.