HR: 0800h
AN: B51B-0372    [Abstracts]
TI: Wetlands for Wastewater: a Visual Approach to Microbial Dynamics
AU: * Joubert, L
EM: lydiaj@stanford.edu
AF: Cell Sciences Imaging Facility, Stanford University, Stanford, CA 94305, United States
AU: Wolfaardt, G
EM: gwolfaar@ryerson.ca
AF: Dept Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
AU: Du Plessis, K
EM: DPlessisK@arc.agric.za
AF: ARC Infruitec-Nietvoorbij, Private Bag x5026, Stellenbosch, 7599, South Africa
AB: The complex character of distillery wastewater comprises high concentrations of sugars, lignins, hemicelluloses, dextrans, resins, polyphenols and organic acids which are recalcitrant to biodegradation. Microorganisms play a key role in the production and degradation of organic matter, environmental pollutants, and cycling of nutrients and metals. Due to their short life cycles microbes respond rapidly to external nutrient loading, with major consequences for the stability of biological systems. We evaluated the feasibility of wetlands to treat winery and distillery effluents in experimental systems based on constructed wetlands, including down-scaled on-site distillery wetlands, small-scale controlled greenhouse systems, and bench-scale mesocosms. Chemical, visual and molecular fingerprinting (t-RFLP) techniques were applied to study the dynamics of planktonic and attached (biofilm) communities at various points in wetlands of different size, retention time and geological substrate, and under influence of shock nutrient loadings. Variable- Pressure Scanning Electron Microscopy (VP-SEM) was applied to visualize microbial colonization, morphotype diversity and distribution, and 3D biofilm architecture. Cross-taxon and predator-prey interactions were markedly influenced by organic loading, while the presence of algae affected microbial community composition and biofilm structure. COD removal varied with geological substrate, and was positively correlated with retention time in gravel wetlands. Planktonic and biofilm communities varied markedly in different regions of the wetland and over time, as indicated by whole-community t-RFLP and VP-SEM. An integrative visual approach to community dynamics enhanced data retrieval not afforded by molecular techniques alone. The high microbial diversity along spatial and temporal gradients, and responsiveness to the physico-chemical environment, suggest that microbial communities maintain metabolic function by modifying species composition in response to fluctuations in their environment. It seems apparent that microbial community plasticity may indeed be the distinguishing characteristic of a successful wetland system.
DE: 0497 Wetlands (1890)
DE: 1890 Wetlands (0497)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting