Changes in the Bacterial Community Structure of Remediated Anthracene-Contaminated Soils

Abstract

Mixing soil or adding earthworms (Eisenia fetida (Savigny, 1826)) accelerated the removal of anthracene, a polycyclic aromatic hydrocarbon, from a pasture and an arable soil, while a non-ionic surfactant (Surfynol® 485) inhibited the removal of the contaminant compared to the untreated soil. It was unclear if the treatments affected the soil bacterial community and consequently the removal of anthracene. Therefore, the bacterial community structure was monitored by means of 454 pyrosequencing of the 16S rRNA gene in the pasture and arable soil mixed weekly, amended with Surfynol® 485, E. fetida or organic material that served as food for the earthworms for 56 days. In both soils, the removal of anthracene was in the order: mixing soil weekly (100%) > earthworms applied (92%) > organic material applied (77%) > untreated soil (57%) > surfactant applied (34%) after 56 days. There was no clear link between removal of anthracene from soil and changes in the bacterial community structure. On the one hand, application of earthworms removed most of the contaminant from the arable soil and had a strong effect on the bacterial community structure, i.e. a decrease in the relative abundance of the Acidobacteria, Chloroflexi and Gemmatimonadetes, and an increase in that of the Proteobacteria compared to the unamended soil. Mixing the soil weekly removed all anthracene from the arable soil, but had little or no effect on the bacterial community structure. On the other hand, application of the surfactant inhibited the removal of anthracene from the arable soil compared to the untreated soil, but had a strong effect on the bacterial community structure, i.e. a decrease in the relative abundance of Cytophagia (Bacteroidetes), Chloroflexi, Gemmatimonadetes and Planctomycetes and an increase in that of the Flavobacteria (Bacteroidetes) and Proteobacteria. Additionally, the removal of anthracene was similar in the different treatments of both the arable and pasture soil, but the effect of application of carrot residue, earthworms or the surfactant on the bacterial community structure was more accentuated in the arable soil than in the pasture soil. It was found that removal of anthracene was not linked to changes in the bacterial community structure.

Response of microbial community structure and metabolic profile to shifts of inlet VOCs in a gas-phase biofilter

“…Hence, we can conclude that Actinobacteria and Proteobacteria played crucial roles in aromatic hydrocarbon purification in this study. Increasing abundance of the phylum Planctomycetes when some aromatic chemicals were being removed have also been confirmed in previous study (Delgado-Balbuena et al 2016 ).…”

Opportunistic Bacteria Dominate the Soil Microbiome Response to Phenanthrene in a Microcosm-Based Study

“…For example, Thomas and Cébron ( 2016 ) found that phenanthrene amendment in the presence of plants did not lead to greater removal of phenanthrene from bulk soil, despite increases in the abundance of PAH-ring hydroxylating genes. Similarly, Delgado-Balbuena et al ( 2016 ) did not find strong relationships between soil microbial community structure and anthracene removal from contaminated soil when applying different remediation strategies. Although these studies offer valuable insights into the microbial molecular ecology of PAH degradation in soils, they vary substantially in their objectives, target habitat, PAH type, and experimental design.…”

Earthworm-induced shifts in microbial diversity in soils with rare versus established invasive earthworm populations

“…The existing studies detailing the effects of earthworms on soil microbial community composition using culture-independent methods are often not directly comparable owing to the differences in experimental design, earthworm functional type, and treatments applied (Bernard et al, 2012, Koubova et al, 2012, Dempsey et al, 2013, Frisli et al, 2013, Koubova et al, 2015, Braga et al, 2016, Delgado-Balbuena et al, 2016. The available information suggests that earthworms boost the growth of fast growing bacteria owing to the production of labile carbon substrates (Braga et al, 2016).…”