Sun, M. University of Georgia, mysun@arches.uga.edu
Aller, R. Marine Sciences Research Center, State University of New York at Stony Brook, raller@ccmail.sunysb.edu
Lee, C. Marine Sciences Research Center, State University of New York at Stony Brook, cindylee@ccmail.sunysb.edu
Wakeham, S. G. Skidaway Institute of Oceanography, stuart@skio.peachnet.edu

 
EFFECTS OF OXYGEN CONTENT AND REDOX OSCILLATION ON DEGRADATION OF CELL-ASSOCIATED LIPIDS AT A SIMULATED SEDIMENT-WATER INTERFACE
 
Degradation of algal lipids were tracked with time under variable redox conditions (oxic, anoxic, and oscillatted oxic/anoxic). Uniformly 13C-labeled algae (13C > 98%) were mixed with Long Island Sound surface sediments to simulate a sediment-water interface (1.5-mm thick sediment exposed to a water reservoir). Variations in concentration of several 13C-labeled algal lipids (fatty acids, phytol and 17:1 alkene) were followed during the incubations. Results showed a large difference (~10X) in degradation rate constant of cell-associated lipids between oxic and anoxic conditions. Frequent exposure to oxic conditions promoted the degradation of cell-associated lipids. Changes in concentrations of two newly-produced 13C-labeled compounds (iso-15:0 fatty acid and C16 alcohol) further indicated that redox conditions and oxic/anoxic oscillation strongly affect microbial degradation of algal lipids. Bacteria biomass is turned over faster under continuously or occasionally oxic conditions than under anoxic conditions. Under anoxic conditions, bacteria convert phytol to C16 alcohol, leading to an accumulation of this compound. In contrast, bacteria efficiently remineralize phytol under oxic conditions without any accumulation of C16 alcohol. The frequency of oxic/anoxic oscillation significantly affected the production and destruction of C16 alcohol, implying that remineralization efficiency of algal lipids by bacteria likely depends on changes in redox conditions.
 
Day: Friday, Feb. 5
Time: 08:45 - 09:00am
Location: Sweeney Center
 
Code: CS63FR0845S