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

PLoS One. 2016 Oct 11;11(10):e0160991. doi: 10.1371/journal.pone.0160991. eCollection 2016.

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.

MeSH terms

  • Acidobacteria / drug effects
  • Acidobacteria / genetics
  • Acidobacteria / growth & development
  • Animals
  • Anthracenes / metabolism*
  • Anthracenes / pharmacology
  • Bacteria / drug effects*
  • Bacteria / genetics
  • Bacteria / growth & development
  • Bacteroidetes / drug effects
  • Bacteroidetes / genetics
  • Bacteroidetes / growth & development
  • Chloroflexi / drug effects
  • Chloroflexi / genetics
  • Chloroflexi / growth & development
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / isolation & purification
  • DNA, Bacterial / metabolism
  • Oligochaeta / metabolism
  • Principal Component Analysis
  • Proteobacteria / drug effects
  • Proteobacteria / genetics
  • Proteobacteria / growth & development
  • RNA, Ribosomal, 16S / chemistry
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Soil Microbiology*
  • Soil Pollutants / chemistry
  • Soil Pollutants / metabolism
  • Soil Pollutants / toxicity
  • Surface-Active Agents / toxicity

Substances

  • Anthracenes
  • DNA, Bacterial
  • RNA, Ribosomal, 16S
  • Soil Pollutants
  • Surface-Active Agents

Grants and funding

The research was funded by ‘Cinvestav’, ‘Instituto de Ciencia y Tecnología del Distrito Federal' (ICTyDF, México), project ‘Infraestructura 205945’ and ‘Apoyo Especial para Fortalecimiento de Doctorado PNPC 2013’ from ‘Consejo Nacional de Ciencia y Tecnología’ (CONACyT, Mexico). LD-B and JMB-L received grant-aided support from ‘Consejo Nacional de Ciencia y Tecnología’ (CONACyT, México), while AR-V from ‘Sistema Nacional de Investigadores' (SNI). The authors thank ABACUS (CONACyT) for providing time on their computer for denoising the DNA sequences.