Pyrosequence analysis of bacterial communities in aerobic bioreactors treating polycyclic aromatic hydrocarbon-contaminated soil |
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Authors: | David R Singleton Stephen D Richardson Michael D Aitken |
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Institution: | (1) Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599-7431, USA;(2) Present address: Solutions-IES, Inc., Raleigh, NC 27607, USA |
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Abstract: | Two aerobic, lab-scale, slurry-phase bioreactors were used to examine the biodegradation of polycyclic aromatic hydrocarbons
(PAHs) in contaminated soil and the associated bacterial communities. The two bioreactors were operated under semi-continuous
(draw-and-fill) conditions at a residence time of 35 days, but one was fed weekly and the other monthly. Most of the quantified
PAHs, including high-molecular-weight compounds, were removed to a greater extent in the weekly-fed bioreactor, which achieved
total PAH removal of 76%. Molecular analyses, including pyrosequencing of 16S rRNA genes, revealed significant shifts in the
soil bacterial communities after introduction to the bioreactors and differences in the abundance and types of bacteria in
each of the bioreactors. The weekly-fed bioreactor displayed a more stable bacterial community with gradual changes over time,
whereas the monthly-fed bioreactor community was less consistent and may have been more strongly influenced by the influx
of untreated soil during feeding. Phylogenetic groups containing known PAH-degrading bacteria previously identified through
stable-isotope probing of the untreated soil were differentially affected by bioreactor conditions. Sequences from members
of the Acidovorax and Sphingomonas genera, as well as the uncultivated “Pyrene Group 2” were abundant in the bioreactors. However, the relative abundances of
sequences from the Pseudomonas, Sphingobium, and Pseudoxanthomonas genera, as well as from a group of unclassified anthracene degraders, were much lower in the bioreactors compared to the
untreated soil. |
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Keywords: | |
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