The goal of this project is to further characterize the biogeochemical processes utilizing dissolved free amino acids in anoxic marine sediments. This work is a renewal of a previous grant and series of experiments utilizing 14C- labelled amino acids and inhibitors of specific microbial processes, focussing on the relationship between sulfate reduction and fermentation reactions in consuming amino acids. A major emphasis of this work will be to quantify the specific intermediates produced from the metabolism of amino acids in anoxic marine sediments (e.g., acetate vs. propionate as opposed to simply total volatile fatty acids). For comparative purposes experiments will be carried out using sediment collected from several locations. Previous studies of glutamic acid and alanine utilization in these sediments will be expanded to include analogous studies involving glycine and lysine. These amino acids have been chosen for study because they are the dominant amino acids. The results of this study have the potential of increasing our knowledge of the controls on amino acid digenesis in anoxic marine sediments.
