HR: 1330h
AN: NB33P-13    [Abstracts]
TI: The Effects of Photosynthesis on Extracellular Enzyme Activity in Periphyton Communities
AU: * Schaecher, M P
EM: mschaech@emich.edu
AF: Department of Biology, Eastern Michigan University, 316 Mark Jefferson, Ypsilanti, MI 48197 United States
AU: Kuehn, K A
EM: kkuehn@emich.edu
AF: Department of Biology, Eastern Michigan University, 316 Mark Jefferson, Ypsilanti, MI 48197 United States
AU: Francoeur, S N
EM: steve.francoeur@emich.edu
AF: Department of Biology, Eastern Michigan University, 316 Mark Jefferson, Ypsilanti, MI 48197 United States
AB: In freshwater wetlands, a diverse assemblage of microorganisms (algae, bacteria, and fungi) grow on and within submerged dead plant material. Litter-associated bacteria and fungi produce a wide array of degradative enzymes that are important in decomposition of detritus. We investigated the potential for photosynthetically-mediated stimulation of heterotrophic extracellular enzyme activity. Microbial communities were grown on natural Typha litter in a local wetland. Samples were collected after 10 and 29 days of microbial colonization. In the laboratory, periphytic algal photosynthesis was manipulated by controlling light (0 or 400 μmol m^-2 s^-1 PAR), while simultaneously quantifying the activities (Vmax) of litter associated β-xylosidase, β-glucosidase, leucine-aminopeptidase, and phosphotase using artificial fluorescent substrates. Activities of β-glucosidase (p=0.006) and phosphotase (p<0.001) were significantly greater in light-exposed communities, suggesting that attached algal photosynthesis stimulated enzyme activities. Thus, algal activity may potentially stimulate the litter decay activities of heterotrophic microbial assemblages in wetland ecosystems.
DE: 4239 Limnology
DE: 4840 Microbiology
DE: 9810 New fields (not classifiable under other headings)
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly