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Article

Enhanced Adsorptive Bioremediation of Heavy Metals (Cd2+, Cr6+, Pb2+) by Methane-Oxidizing Epipelon

1
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
2
University of Chinese Academy of Sciences, Beijing 100049, China
3
College of Environment, Hohai University, Nanjing 210098, China
4
School of Biomedical Science, Charles Sturt University, Wagga Wagga, NSW 2678, Australia
*
Author to whom correspondence should be addressed.
Microorganisms 2020, 8(4), 505; https://doi.org/10.3390/microorganisms8040505
Received: 22 February 2020 / Revised: 28 March 2020 / Accepted: 30 March 2020 / Published: 1 April 2020
(This article belongs to the Special Issue Mono- and Multi-Species Biofilms in Bioprocesses)
Cadmium (Cd), chromium (Cr) and lead (Pb) are heavy metals that have been classified as priority pollutants in aqueous environment while methane-oxidizing bacteria as a biofilter arguably consume up to 90% of the produced methane in the same aqueous environment before it escapes into the atmosphere. However, the underlying kinetics and active methane oxidizers are poorly understood for the hotspot of epipelon that provides a unique micro-ecosystem containing diversified guild of microorganisms including methane oxidizers for potential bioremediation of heavy metals. In the present study, the Pb2+, Cd2+and Cr6+ bioremediation potential of epipelon biofilm was assessed under both high (120,000 ppm) and near-atmospheric (6 ppm) methane concentrations. Epipelon biofilm demonstrated a high methane oxidation activity following microcosm incubation amended with a high concentration of methane, accompanied by the complete removal of 50 mg L−1 Pb2+ and 50 mg L−1 Cd2+ (14 days) and partial (20%) removal of 50 mg L−1 Cr6+ after 20 days. High methane dose stimulated a faster (144 h earlier) heavy metal removal rate compared to near-atmospheric methane concentrations. DNA-based stable isotope probing (DNA-SIP) following 13CH4 microcosm incubation revealed the growth and activity of different phylotypes of methanotrophs during the methane oxidation and heavy metal removal process. High throughput sequencing of 13C-labelled particulate methane monooxygenase gene pmoA and 16S rRNA genes revealed that the prevalent active methane oxidizers were type I affiliated methanotrophs, i.e., Methylobacter. Type II methanotrophs including Methylosinus and Methylocystis were also labeled only under high methane concentrations. These results suggest that epipelon biofilm can serve as an important micro-environment to alleviate both methane emission and the heavy metal contamination in aqueous ecosystems with constant high methane fluxes. View Full-Text
Keywords: epipelon; heavy metals; bioremediation; methane oxidation; DNA-SIP epipelon; heavy metals; bioremediation; methane oxidation; DNA-SIP
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MDPI and ACS Style

Faheem, M.; Shabbir, S.; Zhao, J.; Kerr, P.G.; Sultana, N.; Jia, Z. Enhanced Adsorptive Bioremediation of Heavy Metals (Cd2+, Cr6+, Pb2+) by Methane-Oxidizing Epipelon. Microorganisms 2020, 8, 505. https://doi.org/10.3390/microorganisms8040505

AMA Style

Faheem M, Shabbir S, Zhao J, Kerr PG, Sultana N, Jia Z. Enhanced Adsorptive Bioremediation of Heavy Metals (Cd2+, Cr6+, Pb2+) by Methane-Oxidizing Epipelon. Microorganisms. 2020; 8(4):505. https://doi.org/10.3390/microorganisms8040505

Chicago/Turabian Style

Faheem, Muhammad, Sadaf Shabbir, Jun Zhao, Philip G. Kerr, Nasrin Sultana, and Zhongjun Jia. 2020. "Enhanced Adsorptive Bioremediation of Heavy Metals (Cd2+, Cr6+, Pb2+) by Methane-Oxidizing Epipelon" Microorganisms 8, no. 4: 505. https://doi.org/10.3390/microorganisms8040505

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