PERIPHYTIC EXTRACELLULAR ENZYMATIC ACTIVITY RESPONSES TO MANIPULATION OF OXYGEN, PH, AND LABILE ORGANIC CARBON
Periphyton is an aquatic community comprised of autotrophic and heterotrophic microorganisms bound together in an extracellular matrix. Extracellular enzymatic activity of periphytic microbes contributes to decomposition. Previous studies have documented increased rates of periphytic extracellular enzymatic activity in the presence of active algal photosynthesis. Environmental factors including pH, O2, and labile organic carbon concentration are altered by algal photosynthesis. We experimentally manipulated these environmental factors and observed the responses of four enzymes (leucine-aminopeptidase, beta-xylosidase, phosphatase, and beta-glucosidase), to test the hypothesis that one or more of these environmental factors increases periphytic enzyme activity. Typha (cattail) leaf litter was placed into floating wire-mesh litter baskets and submerged in a wetland pool in southeast Michigan. Enzyme assays were conducted on litter-associated periphyton after 10, 31, and 49 days following litter basket deployment. We observed little change in enzyme activities in response to experimental manipulations, except for a significant increase in phosphatase activity in response to increased pH following the 49-day deployment. These data suggest that photosynthetically-mediated pH shifts could be stimulatory to enzyme activity, and that factors other than those included in our experiments may be more influential.
Jennifer Harper (Primary Presenter/Author), Biology Department, Eastern Michigan University, firstname.lastname@example.org;
Kevin Kuehn (Co-Presenter/Co-Author), The University of Southern Mississippi, email@example.com;
Robert Findlay (Co-Presenter/Co-Author), University of Alabama, firstname.lastname@example.org;
Steve Francoeur (Co-Presenter/Co-Author), Biology Department, Eastern Michigan University, email@example.com;