Identification of benzene-degrading Proteobacteria in a constructed wetland by employing in situ microcosms and RNA-stable isotope probing

• Published in: Applied microbiology and biotechnology Vol. 104; no. 4; pp. 1809 - 1820
• Main Authors: Nitz, Henrike, Duarte, Márcia, Jauregui, Ruy, Pieper, Dietmar H., Müller, Jochen A., Kästner, Matthias
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-02-2020; Springer; Springer Nature B.V
• Subjects: Activated carbon; Arcobacter; Artificial wetlands; Benzene; Betaproteobacteria; Biodegradation; Biomedical and Life Sciences; Biotechnology; Carbon 13; Constructed wetlands; Contamination; Dechloromonas; Degradation; DNA sequencing; Ecological effects; Environmental Biotechnology; Epsilonproteobacteria; Ethylenediaminetetraacetic acid; Granulation; Groundwater; Groundwater pollution; Hydrocarbons; Hydrogenophaga; Incorporation; Investigations; Life Sciences; Microbial Genetics and Genomics; Microbiology; Microcosms; Nucleotide sequencing; Organic compounds; Plants; Pore water; Remediation; RNA; rRNA 16S; Stable isotopes; Technology application; Water pollution; Wetlands; Zoogloea; Germany; RNA-SIP; Constructed wetlands; Benzene degradation; BACTRAPs; Betaproteobacteria
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-019-10323-1

Constructed wetlands (CWs) are effective ecological remediation technologies for various contaminated water bodies. Here, we queried for benzene-degrading microbes in a horizontal subsurface flow CW with reducing conditions in the pore water and fed with benzene-contaminated groundwater. For identification of relevant microbes, we employed in situ microcosms (BACTRAPs, which are made from granulated activated carbon) coupled with
13
C-stable isotope probing and Illumina sequencing of 16S rRNA amplicons. A significant incorporation of
13
C was detected in RNA isolated from BACTRAPs loaded with
13
C-benzene and exposed in the CW for 28 days. A shorter incubation time did not result in detectable
13
C incorporation. After 28 days, members from four genera, namely
Dechloromonas
,
Hydrogenophaga
, and
Zoogloea
from the
Betaproteobacteria
and
Arcobacter
from the
Epsilonproteobacteria
were significantly labeled with
13
C and were abundant in the bacterial community on the BACTRAPs. Sequences affiliated to
Geobacter
were also numerous on the BACTRAPs but apparently those microbes did not metabolize benzene as no
13
C label incorporation was detected. Instead, they may have metabolized plant-derived organic compounds while using the BACTRAPs as electron sink. In representative wetland samples, sequences affiliated with
Dechloromonas
,
Zoogloea
, and
Hydrogenophaga
were present at relative proportions of up to a few percent. Sequences affiliated with
Arcobacter
were present at < 0.01% in wetland samples. In conclusion, we identified microbes of likely significance for benzene degradation in a CW used for remediation of contaminated water.