Metabolic and molecular approaches to the study of bacterial communities in wetlands of the Alberta Athabasca oil sands region.

摘要

Bacterial communities in wetlands from the Athabasca region (Alberta, Canada) were surveyed and their utility as bio-indicators for wetland reclamation was assessed. Sediment samples were collected from wetlands categorized as: (1) natural (off mining leases), (2) reference (on mining sites but not directly impacted by oil sands processed material (OSPM)), and (3) OSPM (directly affected by OSPM). Wetlands of the latter two groups ranged in age from 11 to 24 years. Analysis involved community level physiological profiling (CLPP) with BIOLOG(TM) EcoPlates, and denaturing gradient gel electrophoresis (DGGE). Multivariate analysis applied to data from both techniques revealed differences in the bacterial communities based on site type; although overlap between groups occurred. Principal component analysis (PCA) and cluster analysis applied to CLPP data revealed a trend in which communities in OSPM sites were most similar to each other, followed by those in natural sites, and communities in reference wetlands were variable. The vegetated areas of a wetland displayed increased functional richness and diversity (as measured by CLPP) compared to non-vegetated areas. DGGE analysis applied to the total bacterial community revealed the highest number of operational taxonomic units (OTUs) in OSPM samples; the 2008 and 2009 OSPM samples contained an average of 22+/-4.5 and 22.4+/-5.1 OTUs, respectively, while reference sites contained 17.7+/-4.9 (2008) and 16.4+/-1.8 (2009) and natural sites contained 17.1+/-4.4 (2008) and 20.5+/-0.7 (2009). When DGGE was applied to the bacterial subgroups, gamma-Proteobacteria and Actinomycetes, clustering effects based on site-type were more evident through PCA than when a total bacterial approach was taken. Within OSPM wetlands, gamma-Proteobacteria populations were varied while Actinomycetes were similar across sites. Overall, there are clear functional (CLPP) and genetic (DGGE) differences between bacterial communities in OSPM and less impacted sites, although communities are not distinct, potentially reflecting the age of the wetlands studied and adaptation of the communities to oil sands materials. Given that CLPP and DGGE could distinguish between communities based on site type, both may be useful for monitoring microbial communities in Athabasca wetlands throughout reclamation. In particular, CLPP and group-specific DGGE are recommended as tools for community monitoring.