Temporal bacterial diversity associated with metal-contaminated river sediments

Abstract

The temporal activity, abundance and diversity of microbial communities were evaluated across a metal-contamination gradient around a Superfund site in Montana. In order to analyze short-term variability, samples were collected from six sites on four occasions over 12 months. Measurements of community activity, diversity and richness, quantified by dehydrogenase activity and through denaturant gradient gel electrophoresis (DGGE), respectively, were higher at contaminated sites adjacent to the smelter, relative to reference sites. 16S rRNA gene copy numbers, measured by quantitative PCR, showed seasonal variability, yet were generally higher within polluted sediments. Jaccard similarity coefficients of DGGE profiles, found sites to cluster based primarily on geographical proximity rather than geochemical similarities. Intra-site clustering of the most polluted sites also suggests a stable metal-tolerant community. Sequences from DGGE-extracted bands were predominantly Beta and Gammaproteobacteria, although the communities at all sites generally maintained a diverse phylogeny changing in composition throughout the sampling period. Spearman's rank correlations analysis found statistically significant relationships between community composition and organic carbon (r-value = 0.786) and metals (r-values As = 0.65; Cu = 0.63; Zn = 0.62). A diverse and abundant community at the most polluted site indicates that historical contamination selects for a metal-resistant microbial community, a finding that must be accounted for when using the microbial community within ecosystem monitoring studies. This study highlights the importance of using multiple time-points to draw conclusions on the affect of metal contamination.

Characteristics of Sediment Bacterial Community in Response to Environmental Impacts in a Sewage Polluted River

“…In the present study, bacterial community abundance and structure among four sites sampled during different seasons of the same year were explored by molecular and statistical analyses. The bacterial abundance was concurrent with that observed for other freshwater sediments ( Dorador et al, 2010;Jiang et al, 2007) , but lower than the typical range reported for sediment environments ( Bouskill et al, 2010;Eiler and Bertilsson, 2007) . The DGGE patterns suggested large numbers of bacterial species and high levels of bacterial diversity in river sediments, which was also confirmed by the Shannon-Weaver diversity index ( Bushaw-Newton et al, 2012;Cetecioǧlu et al, 2009 ) .…”

Bacterial community responses to a gradient of alkaline mountaintop mine drainage in Central Appalachian streams

“…Earlier work shows that salinity and trace metals generate significant changes in microbial community composition (Baker and Banfield, 2003;Feris et al, 2003;Giller et al, 2009;Auguet et al, 2010;Lami et al, 2013). A number of studies have found that Cd and Zn in particular alter microbial community composition (Ganguly and Jana, 2002;Sverdrup et al, 2006;Bouskill et al, 2010;Xie et al, 2011).…”

Effect of Pollution on Aquatic Microbial Diversity

“…Beta-, Gamma-, and Epsilonproteobacteria were dominant in nitrate-treated sediments, while Firmicutes, Chloroflexi, and Deltaproteobacteria were dominant in the untreated sediments. Estimation of temporal bacterial diversity in the sediments of Clark Fork River, Montana, USA, a river exposed to complex mixtures of metals, by Bouskill and co-workers revealed a relatively stable, metal-tolerant community (Bouskill et al 2010). Predominant community members belonged to Beta-and Gammaproteobacteria, and statistically significant relationship between community composition and metals was established, indicating natural selection towards a metal-resistant microbial population.…”