The potential functional diversity of the bacterial community in biofilters

Jason Grove, The Delphi Group, Toronto, Sustainability Faculty Candidate

27 April 2010 at 11:00

Location: JHE 342

Air-phase biofiltration is a technology for the removal of biodegradable pollutants from waste air. Humidified air flows through a packed bed; contaminants partition between the air and a biofilm on the surface of the packing and are degraded by a mixed microbial community. Despite the fundamental importance of the microbial community to this process, it remains relatively little studied and details about the community and its dynamics are unclear. We used community-level physiological profiling on the basis of sole-carbon substrate utilisation profiles to investigate the spatial and dynamic variation in the bacterial community. Changes in the profile obtained are indicative of underlying structural or physiological changes. The results show that this method is suitable to characterize the community in laboratory-scale biofilters, with samples taken simultaneously showing good reproducibility and indicating some local homogeneity in the microbial community function. Over time, the community shows periods of stability separated by relatively rapid changes, sometimes developing stratification across the bed; biofilter operation (removal of the contaminant) is maintained during these transitions. There is evidence from the literature that mixed communities may respond chaotically to perturbations and our results are consistent with this hypothesis. Significant challenges remain in interpreting and applying information about the ecology of mixed microbial systems. Further work is necessary to develop an understanding of the dynamic response of communities in response to perturbations. This may lead to practical future applications, for example in distinguishing characteristics of robust communities able to thrive and withstand changes in operating conditions from those of fragile communities prone to failure, or in evaluating the effectiveness of operating conditions, nutrient application, etc.

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