Impact of Long-Term Diesel Contamination on Soil Microbial Community Structure

Abstract

e Microbial community composition and diversity at a diesel-contaminated railway site were investigated by pyrosequencing of bacterial and archaeal 16S rRNA gene fragments to understand the interrelationships among microbial community composition, pollution level, and soil geochemical and physical properties. To this end, 26 soil samples from four matrix types with various geochemical characteristics and contaminant concentrations were investigated. The presence of diesel contamination significantly impacted microbial community composition and diversity, regardless of the soil matrix type. Clean samples showed higher diversity than contaminated samples (P < 0.001). Bacterial phyla with high relative abundances in all samples included Proteobacteria, Firmicutes, Actinobacteria, Acidobacteria, and Chloroflexi. High relative abundances of Archaea, specifically of the phylum Euryarchaeota, were observed in contaminated samples. Redundancy analysis indicated that increased relative abundances of the phyla Chloroflexi, Firmicutes, and Euryarchaeota correlated with the presence of contamination. Shifts in the chemical composition of diesel constituents across the site and the abundance of specific operational taxonomic units (OTUs; defined using a 97% sequence identity threshold) in contaminated samples together suggest that natural attenuation of contamination has occurred. OTUs with sequence similarity to strictly anaerobic Anaerolineae within the Chloroflexi, as well as to Methanosaeta of the phylum Euryarchaeota, were detected. Anaerolineae and Methanosaeta are known to be associated with anaerobic degradation of oil-related compounds; therefore, their presence suggests that natural attenuation has occurred under anoxic conditions. This research underscores the usefulness of next-generation sequencing techniques both to understand the ecological impact of contamination and to identify potential molecular proxies for detection of natural attenuation.

High concentrations of bioavailable heavy metals impact freshwater sediment microbial communities

“…These taxa have also been connected to bulk terrestrial soils contaminated with Ni, Co, and Zn (Harichova et al 2012) and hydrocarbons (Sutton et al 2013). Actinobacteria have been isolated and observed to possess mechanisms promoting resistance to heavy metal disturbance (Schmidt et al 2005), and have also been isolated from contaminated subsurface sediments (Bollmann et al 2010).…”

On-site and in situ remediation technologies applicable to petroleum hydrocarbon contaminated sites in the Antarctic and Arctic

“…Bioaugmentation can encompass the addition of a pre-adapted bacterial strain, addition of a pre-adapted consortium or introduction of genetically engineered bacteria to target specific contaminants at a site (Tyagi et al 2011). Characterization of hydrocarbondegrading microorganisms in Antarctic soils demonstrates that isolation of psychrotolerant bacteria capable of metabolizing petroleum hydrocarbons in pure cultures can assist in the development of tailored bacterial formulae for bioaugmentation (Sutton et al 2013;Vá zquez et al 2013). Stallwood et al (2005) isolated Pseudomonas borealis from clean and petroleum hydrocarbon contaminated soils of the South Orkney Islands, Antarctica.…”

Culture-Independent Molecular Tools for Soil and Rhizosphere Microbiology

“…Due to reasonably longer sequences compared to the other high-throughput sequencing platforms (see below sections) and higher output compared to conventional cloning sequencing approaches, pyrosequencing allows the detection of rare bacterial and archaea genera. Recently, this method has been extensively used to characterize composition and diversity of soil microbial communities [20,107,[160][161][162][163] and has also been applied to understand the effect of heavy metals and disturbances on soil microbial communities [162,164,165]. The particularity of this method is that it provides reads that are long enough (average 500 bp but up to 1000 bp) to assign probable taxonomic identity up to genus level and rare groups can be detected as thousands of reads can be obtained per sample.…”