Selection for Cu-Tolerant Bacterial Communities with Altered Composition, but Unaltered Richness, via Long-Term Cu Exposure

Abstract

Toxic metal pollution affects the composition and metal tolerance of soil bacterial communities. However, there is virtually no knowledge concerning the responses of members of specific bacterial taxa (e.g., phyla or classes) to metal toxicity, and contradictory results have been obtained regarding the impact of metals on operational taxonomic unit (OTU) richness. We used tagcoded pyrosequencing of the 16S rRNA gene to elucidate the impacts of copper (Cu) on bacterial community composition and diversity within a well-described Cu gradient (20 to 3,537 g g ؊1 ) stemming from industrial contamination with CuSO 4 more than 85 years ago. DNA sequence information was linked to analysis of pollution-induced community tolerance (PICT) to Cu, as determined by the [ 3 H]leucine incorporation technique, and to chemical characterization of the soil. PICT was significantly correlated to bioavailable Cu, as determined by the results seen with a Cu-specific bioluminescent biosensor strain, demonstrating a specific community response to Cu. The relative abundances of members of several phyla or candidate phyla, including the Proteobacteria, Bacteroidetes, Verrumicrobia, Chloroflexi, WS3, and Planctomycetes, decreased with increasing bioavailable Cu, while members of the dominant phylum, the Actinobacteria, showed no response and members of the Acidobacteria showed a marked increase in abundance. Interestingly, changes in the relative abundances of classes frequently deviated from the responses of the phyla to which they belong. Despite the apparent Cu impacts on Cu resistance and community structure, bioavailable Cu levels did not show any correlation to bacterial OTU richness (97% similarity level). Our report highlights several bacterial taxa responding to Cu and thereby provides new guidelines for future studies aiming to explore the bacterial domain for members of metal-responding taxa.

Profile of bacterial communities in South African mine-water samples using Illumina next-generation sequencing platform

“…Compared with highly diverse Proteobacteria communities, the other communities in both the mine-water samples were less complex and only Bacteroidetes accounted for more than 10 % of the reads in vanadium mine water (Table S1). It has been stated that most of the bacteria inhabiting the metal-contaminated water systems are able to develop various types of resistance mechanisms to adapt to and resist metal toxicity; as a result, microbial diversity remains high (Gough and Stahl 2011;Berg et al 2012). In the vanadium mine water, the occurrence of Marinobacter sp.…”

Illumina MiSeq sequencing investigation on the contrasting soil bacterial community structures in different iron mining areas

“…Recent developments in molecular fingerprinting techniques, such as denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism, and real-time PCR quantification, have allowed researchers to investigate the microbial diversity variations in soils contaminated with heavy metals (Berg et al 2012;Cáliz et al 2013;Giloteaux et al 2011;Petrić et al 2011;Zhao et al 2014). Molecular fingerprint techniques have high resolution; however, the fingerprint complexity caused by the high richness of indigenous microbial communities in soil may mask the changes induced by heavy metals (Gomes et al 2010).…”

“…Berg observed that the relative abundance of bacterial groups changed within a Cu gradient (20 to 3537 mg/kg), which originated from CuSO 4 contamination over 85 years ago (Berg et al 2012). Margarita discussed the diversity of taxonomic groups after a 60-day incubation period with Cd concentrations reaching 12.5 mg/kg (Ros et al 2009).…”

Bacterial communities in trace metal contaminated lake sediments are dominated by endospore-forming bacteria

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