The use of microbial gene abundance in the development of fuel remediation guidelines in polar soils

Abstract

Terrestrial fuel spills in Antarctica commonly occur on ice-free land around research stations as the result of human activities. Successful spill clean-ups require appropriate targets that confirm contaminated sites are no longer likely to pose environmental risk following remediation. These targets are based on knowledge of the impacts of contaminants on the soil ecosystem and on the response of native biota to contamination. Our work examined the response of soil microbial communities to fuel contamination by measuring the abundance of genes involved in critical soil processes, and assessed the use of this approach as an indicator of soil health in the presence of weathered and fresh fuels. Uncontaminated and contaminated soils were collected from the site of remediation treatment of an aged diesel spill at Casey Station, East Antarctica in December 2012. Uncontaminated soil was spiked with fresh Special Antarctic Blend (SAB) diesel to determine the response of the genes to fresh fuel. Partly remediated soil containing weathered SAB diesel was diluted with uncontaminated soil to simulate a range of concentrations of weathered fuel and used to determine the response of the genes to aged fuel. Quantitative PCR (qPCR) was used to measure the abundance of rpoB, alkB, cat23, and nosZ in soils containing SAB diesel. Differences were observed between the abundance of genes in control soils versus soils containing weathered and fresh fuels. Typical dose-response curves were generated for genes in response to the presence of fresh fuel. In contrast, the response of these genes to the range of weathered fuel appeared to be due to dilution, rather than to the effect of the fuel on the microbial community. Changes in microbial genes in response to fresh contamination have potential as a sensitive measure of soil health and for assessments of the effect of fuel spills in polar soils. This will contribute to the development of remediation guidelines to assist in management decisions on when the impact of a fuel spill warrants remediation.

Digital PCR as an Emerging Tool for Monitoring of Microbial Biodegradation

“…Besides, during the PAHs biodegradation in the soil, quantification of different ITS regions was used for determining the abundance of each degrading microbe [75]. In addition, Richardson et al [76] used the B subunit of ribosomal polymerase (rpoB) gene as a marker gene to determine the total microbial population in the fuel-contaminated soil as it is present in almost all cells.…”

Endophytic root bacteria associated with the natural vegetation growing at the hydrocarbon-contaminated Bitumount Provincial Historic site

“…Similar results have been documented in studies that focused of the bacterial gene abundance of hydrocarbon degraders. For example, Richardson et al (2015) observed that the level of hydrocarbon genes in soil bacteria was higher than that of the total bacterial population (calculated by rpoB) in both contaminated and uncontaminated soils at a remediation site of an aged diesel spill in east Antarctica. Additionally, Yergeau et al (2012) observed high abundances of hydrocarbon-degrading genes within the soil at a bioremediation site in the Canadian Arctic.…”

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

“…Similarly, through dose-response modelling of the bacterial amoA gene, Van Dorst et al (2014) determined an average effective concentration responsible for a 20% change in phylogenetic diversity of 155 mg/kg as an indicator of soil health at Macquarie Island. In addition, microbial gene abundance has also been recently investigated for the development of remediation guidelines in polar soils (Richardson et al 2014). Results from petroleum hydrocarbon contaminated soils at Casey Station, Antarctica, suggest that changes in microbial genes in response to fresh contamination may act as a suitable indicator of soil health (Richardson et al 2014).…”

“…Results from petroleum hydrocarbon contaminated soils at Casey Station, Antarctica, suggest that changes in microbial genes in response to fresh contamination may act as a suitable indicator of soil health (Richardson et al 2014). However the response of genes to weathered hydrocarbons requires further investigation (Richardson et al 2014).…”