In constructed wetlands, microorganisms associated with plants are assumed to play a major role. A one-year survey was conducted in five vertical flow constructed wetland systems that had been operating from 2 months to 8 years in small French villages (100–500 People Equivalent) to provide a better understanding of microbiological activity. The objective of our study was to highlight the most important factor generating variability between microorganisms communities compared to treatment performances. Results of community level physiological profiling using Biolog Ecoplates were analyzed using principal component analysis. The greatest microbial activity was observed in the oldest wetland during summer. Profiles of fed and rest bed were differentiated by the nature of the main carbon source metabolized. Whereas carbohydrates and carboxylic acids appeared to be better assimilated with fed beds, it seemed that phosphate compounds as well as amines allowed better growth in the plates inoculated with samples of rest beds. In all fed beds, the most important parameters affecting the diversity were the season and the age of the wetlands. There were only slight profile differences between surface and subsurface samples and between the first and second stage samples. 1. Introduction In constructed wetlands (CWs), it is widely recognized that microorganisms associated with macrophytes play a major role in pollutant removal. Over the last ten years a greater focus has been put on understanding microorganisms diversity and spatial distribution, on characterizing bacterial communities, or on monitoring microbial biomass. A large number of biochemical tools were successfully adapted to monitor microorganisms in CWs, such as epifluorescence, enzymatic activities, protein concentration, flow cytometry, fish probes, PCR, and DGGE [1–6]. In vertical flow constructed wetlands (VFCWs), pollutant removal efficiency (especially TKN removal) can be affected by several factors including season, CW age, and feeding mode (batch loads, periods of rest, etc.) Our study aimed at verifying whether treatment performance was linked or not to microbial diversity by applying the community-level physiological profiles (CLPPs) method using Biolog EcoPlate for constructed wetlands microorganism communities. The CLPP method using microtiterplates with multiple sole-carbon sources has become a popular tool for the comparison of microbial communities with respect to their functional potential. CLPP was successfully adapted to the study of complex communities [7]. This method was shown to
References
[1]
S. R. Ragusa, D. McNevin, S. Qasem, and C. Mitchell, “Indicators of biofilm development and activity in constructed wetlands microcosms,” Water Research, vol. 38, no. 12, pp. 2865–2873, 2004.
[2]
J. D. C. Baptista, T. Donnelly, D. Rayne, and R. J. Davenport, “Microbial mechanisms of carbon removal in subsurface flow wetlands,” Water Science and Technology, vol. 48, no. 5, pp. 127–134, 2003.
[3]
J. McHenry and A. Werker, “In-situ monitoring of microbial biomass in wetland mesocosms,” Water Science and Technology, vol. 51, no. 9, pp. 233–241, 2005.
[4]
F. Chazarenc and G. Merlin, “Influence of surface layer on hydrology and biology of gravel bed vertical flow constructed wetlands,” Water Science and Technology, vol. 51, no. 9, pp. 91–97, 2005.
[5]
Ch. Münch, P. Kuschk, and I. R？ske, “Root stimulated nitrogen removal: only a local effect or important for water treatment?” Water Science and Technology, vol. 51, no. 9, pp. 185–192, 2005.
[6]
C. Criado and E. Bécares, “Characterization of bacterial communities of a constructed wetland in cold conditions,” Journal of General and Applied Microbiology, vol. 51, no. 3, pp. 197–201, 2005.
[7]
J. L. Garland and A. L. Mills, “Classification and characterization of heterotrophic microbial communities on the basis of patterns of community-level sole-carbon-source utilization,” Applied and Environmental Microbiology, vol. 57, no. 8, pp. 2351–2359, 1991.
[8]
C. A. Schneider, K. Mo, and S. N. Liss, “Applying phenotypic fingerprinting in the management of wastewater treatment systems,” Water Science and Technology, vol. 37, no. 4-5, pp. 461–464, 1998.
[9]
S. K. Kaiser, J. B. Guckert, and D. W. Gledhill, “Comparison of activated sludge microbial communities using microplates,” Water Science and Technology, vol. 37, no. 4-5, pp. 57–63, 1998.
[10]
D. M. Moll and R. S. Summers, “Assessment of drinking water filter microbial communities using taxonomic and metabolic profiles,” Water Science and Technology, vol. 39, no. 7, pp. 83–89, 1999.
[11]
J. A. Grove, H. Kautola, S. Javadpour, M. Moo-Young, and W. A. Anderson, “Assessment of changes in the microorganism community in a biofilter,” Biochemical Engineering Journal, vol. 18, no. 2, pp. 111–114, 2004.
[12]
C.-P. Yu and Y.-H. Yu, “Evaluation of biodegradability by the reduction of Tetrazolium Violet in microplates,” Biotechnology Letters, vol. 22, no. 11, pp. 909–913, 2000.
[13]
Biolog, June 2006, http://www.biolog.com/pdf/eco_microplate_sell_sheet.pdf.
[14]
J. B. Guckert, G. J. Carr, T. D. Johnson, B. G. Hamm, D. H. Davidson, and Y. Kumagai, “Community analysis by Biolog: curve integration for statistical analysis of activated sludge microbial habitats,” Journal of Microbiological Methods, vol. 27, no. 2-3, pp. 183–197, 1996.
[15]
P. Molle, A. Lienard, C. Boutin, G. Merlin, and A. Iwema, “How to treat raw sewage with constructed wetlands: an overview of the French systems,” Water Science and Technology, vol. 51, no. 9, pp. 11–21, 2005.
[16]
F. Chazarenc, Optimisation des systèmes de traitement des eaux usées domestiques par filtres plantés de macrophytes, Ph.D. thesis, Université de Savoie, France, 2003.
[17]
K. R. Hench, A. J. Sexstone, and G. K. Bissonnette, “Heterotrophic community-level physiological profiles of domestic wastewater following treatment by small constructed subsurface flow wetlands,” Water Environment Research, vol. 76, no. 5, pp. 468–473, 2004.
