Halomonas

Pseudomonas

Biostimulation

Ecology

Bacteria

Biology

Bioremediation

Arthrobacter

Environmental remediation

Mesocosm

16S ribosomal RNA

Genetics

Bioaugmentation

Microbacterium

Environmental chemistry

Soil contamination

Contamination

Rhodococcus

Environmental science

Microbial population biology

Chemistry

Nutrient

Journal of Environmental Management

Polycyclic aromatic hydrocarbons (PAHs) represent a group of hazardous compounds that are ubiquitous and persistent. The main aim of this study was to investigate the degradation of PAHs in chronically contaminated, aged and weathered soils obtained from a former gas plant of Australia. Biostimulation and bioaugmentation using individual isolates (Rhodococcus sp. (NH2), Achromobacter sp. (NH13), Oerskovia paurometabola (NH11), Pantoea sp. (NH15), Sejongia sp. (NH20), Microbacterium maritypicum (NH30) and Arthrobacter equi (NH21)) and a consortium of these isolates were tested during mesocosm studies. A significant reduction (99%) in PAH concentration was observed in all the treatments. In terms of the abundance of PAH-degrading genes and microbial community structure during PAH degradation, qPCR results revealed that Gram-positive bacteria were dominant over other bacterial communities in all the treatments. 16S sequencing results revealed that the inoculated organisms did not establish themselves during the treatment. However, substantial bacterial community changes during the treatments were observed, suggesting that the natural community exhibited sufficient resilience and diversity to enable an active, but changing degrading community at all stages of the degradation process. Consequently, biostimulation is proposed as the best strategy to remediate PAHs in aged, weathered and chronically contaminated soils.

Influence of bioaugmentation and biostimulation on PAH degradation in aged contaminated soils: Response and dynamics of the bacterial community