HR: 1330h
AN: NB33I-15    [Abstracts]
TI: Changes in Microbial Extracellular Enzyme Activity Associated with Decreasing Organic Matter Particle Size in a Louisiana Cypress Swamp
AU: * Vallaire, S
EM: scarlett.vallaire@selu.edu
AF: Southeastern Louisiana University, Dept. of Biological Sciences, SLU 10736, Hammond, La 70402 United States
AU: Jackson, C R
EM: cjackson@selu.edu
AF: Southeastern Louisiana University, Dept. of Biological Sciences, SLU 10736, Hammond, La 70402 United States
AB: Microbial extracellular enzymes are vital to the decomposition of fine particulate organic matter (FPOM) in aquatic systems. However, little is known about variations in the activity of these enzymes with decreasing FPOM size, and even less is known about the importance of these enzymes in the decomposition of FPOM in wetland sediments. Three sediment samples were collected from a Louisiana cypress swamp and sieved into five size ranges, consisting of course particulate organic matter (>1 mm), and four different sizes of FPOM: 0.5-1mm, 0.25-0.5mm, 0.125-0.25mm, and 0.063-0.125mm. For each size range, we assayed the activities of six enzymes involved in lignocellulose decomposition. Activities of beta-glucosidase, beta-xylosidase, cellobiohydrolase, and beta-N-acetylglucosaminidase were strongly correlated with each other, and the activities of all four hydrolytic enzymes began to decrease in activity on FPOM less than 0.5mm. Peroxidase activity was generally low, but peaked on 0.125-0.25mm particles. Phenol oxidase activity was not detected in any samples, regardless of particle size. These results show that changes in microbial enzyme activity occur as FPOM decreases in size, particularly on particles below a 0.25-0.5mm threshold. These changes may reflect differences in both the microbial community and the nature of the FPOM.
DE: 0400 Biogeosciences
DE: 1890 Wetlands
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly