Pyrosequence analyses of bacterial communities during simulated in situ bioremediation of polycyclic aromatic hydrocarbo
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ENVIRONMENTAL BIOTECHNOLOGY
Pyrosequence analyses of bacterial communities during simulated in situ bioremediation of polycyclic aromatic hydrocarbon-contaminated soil David R. Singleton & Maiysha D. Jones & Stephen D. Richardson & Michael D. Aitken
Received: 28 August 2012 / Revised: 15 October 2012 / Accepted: 18 October 2012 # Springer-Verlag Berlin Heidelberg 2012
Abstract Barcoded amplicon pyrosequencing was used to generate libraries of partial 16S rRNA genes from two columns designed to simulate in situ bioremediation of polycyclic aromatic hydrocarbons (PAHs) in weathered, contaminated soil. Both columns received a continuous flow of artificial groundwater but one of the columns additionally tested the impact of biostimulation with oxygen and inorganic nutrients on indigenous soil bacterial communities. The penetration of oxygen to previously anoxic regions of the columns resulted in the most significant community changes. PAH-degrading bacteria previously determined by stable-isotope probing (SIP) of the untreated soil generally responded negatively to the treatment conditions, with only members of the Acidovorax and a group of uncharacterized PAH-degrading Gammaproteobacteria maintaining a significant presence in the columns. Additional groups of sequences associated with the Betaproteobacterial family Rhodocyclaceae (including those associated with PAH degradation in other soils), and the Thiobacillus, Thermomonas, and Bradyrhizobium genera were also present in high abundance in the biostimulated column. Similar community D. R. Singleton (*) : M. D. Jones : S. D. Richardson : M. D. Aitken Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Room 1108, Michael Hooker Research Center, CB#7431, Chapel Hill, NC 27599-7431, USA e-mail: [email protected] Present Address: M. D. Jones Procter and Gamble Mason Business Center, Mason, OH 45040, USA Present Address: S. D. Richardson Solutions-IES, Inc., Raleigh, NC 27607, USA
responses were previously observed during biostimulated ex situ treatment of the same soil in aerobic, slurry-phase bioreactors. While the low relative abundance of many SIPdetermined groups in the column libraries may be a reflection of the slow removal of PAHs in that system, the similar response of known PAH degraders in a higher-rate bioreactor system suggests that alternative PAH-degrading bacteria, unidentified by SIP of the untreated soil, may also be enriched in engineered systems. Keywords Pyrosequencing . Polycyclic aromatic hydrocarbons . Bioremediation
Introduction Physical and chemical methods are often used for the cleanup of polycyclic aromatic hydrocarbon (PAH)-contaminated sites (Gan et al. 2009; U. S. Environmental Protection Agency 2004, 2007), but engineered systems that rely on bioremediation are a potentially more cost-effective method for the treatment of soils (Gan et al. 2009). However, a wide variety of variables can impact the success of a biological treatment process. For example, in a
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