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Stimulating soil microorganisms for mineralizing the herbicide isoproturon by means of microbial electroremediating cells.

Rodrigo Quejigo J, Dörfler U, Schroll R, Esteve-Núñez A - Microb Biotechnol (2016)

Bottom Line: Microbial electroremediating cells (MERCs) consist in a variety of bioelectrochemical devices that aim to overcome electron acceptor limitation and maximize metabolic oxidation with the purpose of enhancing the biodegradation of a pollutant in the environment.The objective of this work was to use MERCs principles for stimulating soil bacteria to achieve the complete biodegradation of the herbicide (14) C-isoproturon (IPU) to (14) CO(2) in soils.The remarkable impact of electrodes on the microbial activity of natural communities suggests a promising future for this emerging environmental technology that we propose to name bioelectroventing.

View Article: PubMed Central - PubMed

Affiliation: University of Alcalá, Alcalá de Henares, Madrid, Spain.

No MeSH data available.


Related in: MedlinePlus

A. Distribution and mass balance of different soil treatments regarding initial radioactivity of 14C‐IPU. B. Extractable and non‐extractable 14C residues in carbon felt electrodes used under different treatments. Bars represent standard deviation.
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mbt212351-fig-0003: A. Distribution and mass balance of different soil treatments regarding initial radioactivity of 14C‐IPU. B. Extractable and non‐extractable 14C residues in carbon felt electrodes used under different treatments. Bars represent standard deviation.

Mentions: In addition to the cumulative 14CO2 mineralization, the soil‐ and electrode‐associated radioactivity should be measured in order to conform the 14C mass balance established in our experimental system. So thus, methanol extractable residue (ER) and non‐extractable residues (NER) of 14C‐IPU that remained in the soil and electrodes during the course of the assays were shown in Fig. 3A. Interestingly, these mass balances ranged between 91.2% and 98.4% of the initially supplied 14C‐IPU under pol‐MERCs and electrode‐free control respectively. This parameter was therefore an indicator of the effectiveness of our experimental design and underlines the presence of potential losses of 14CO2, especially under conditions of high mineralization rates (pol‐MERCs treatment). The extractable 14C‐residues in the soil samples varied considerably between the different experimental conditions after 25 days of incubation. The ER did reach 53.9% of the applied radioactivity for the electrode‐free control but it did just 15% in soil under the pol‐MERCs treatment. On the contrary, a similar distribution was observed for NER regardless the treatment: 43.6% for electrode‐free control and 40.4% for pol‐MERCs. Examining the 14C mass balance of the long‐term assay (110 days), we observed an increase in the NER in comparison with the standard pol‐MERCs. The formation of NER are often explained by binding of a xenobiotic to the soil matrix, specially to the soil organic matter and has been reported that IPU metabolites are mostly adsorbed onto organic matter in soils (Ertli et al., 2004). Another possible pathway for the formation of NER is the 14C‐IPU‐degradation by microorganisms that can use it as an energy source and for microbial growth; as a result, 14C‐residues are incorporated into biomolecules and e.g. subsequently bound to soil (‘apparent NER’) when microbes die (Grundmann et al., 2011). Positive correlations between NER formation and IPU aerobic mineralization have been previously reported (Alletto et al., 2006), which could explain the similar NER fraction under electrode‐free control and pol‐MERCs despite the broad 14C‐IPU cumulative mineralization.


Stimulating soil microorganisms for mineralizing the herbicide isoproturon by means of microbial electroremediating cells.

Rodrigo Quejigo J, Dörfler U, Schroll R, Esteve-Núñez A - Microb Biotechnol (2016)

A. Distribution and mass balance of different soil treatments regarding initial radioactivity of 14C‐IPU. B. Extractable and non‐extractable 14C residues in carbon felt electrodes used under different treatments. Bars represent standard deviation.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835573&req=5

mbt212351-fig-0003: A. Distribution and mass balance of different soil treatments regarding initial radioactivity of 14C‐IPU. B. Extractable and non‐extractable 14C residues in carbon felt electrodes used under different treatments. Bars represent standard deviation.
Mentions: In addition to the cumulative 14CO2 mineralization, the soil‐ and electrode‐associated radioactivity should be measured in order to conform the 14C mass balance established in our experimental system. So thus, methanol extractable residue (ER) and non‐extractable residues (NER) of 14C‐IPU that remained in the soil and electrodes during the course of the assays were shown in Fig. 3A. Interestingly, these mass balances ranged between 91.2% and 98.4% of the initially supplied 14C‐IPU under pol‐MERCs and electrode‐free control respectively. This parameter was therefore an indicator of the effectiveness of our experimental design and underlines the presence of potential losses of 14CO2, especially under conditions of high mineralization rates (pol‐MERCs treatment). The extractable 14C‐residues in the soil samples varied considerably between the different experimental conditions after 25 days of incubation. The ER did reach 53.9% of the applied radioactivity for the electrode‐free control but it did just 15% in soil under the pol‐MERCs treatment. On the contrary, a similar distribution was observed for NER regardless the treatment: 43.6% for electrode‐free control and 40.4% for pol‐MERCs. Examining the 14C mass balance of the long‐term assay (110 days), we observed an increase in the NER in comparison with the standard pol‐MERCs. The formation of NER are often explained by binding of a xenobiotic to the soil matrix, specially to the soil organic matter and has been reported that IPU metabolites are mostly adsorbed onto organic matter in soils (Ertli et al., 2004). Another possible pathway for the formation of NER is the 14C‐IPU‐degradation by microorganisms that can use it as an energy source and for microbial growth; as a result, 14C‐residues are incorporated into biomolecules and e.g. subsequently bound to soil (‘apparent NER’) when microbes die (Grundmann et al., 2011). Positive correlations between NER formation and IPU aerobic mineralization have been previously reported (Alletto et al., 2006), which could explain the similar NER fraction under electrode‐free control and pol‐MERCs despite the broad 14C‐IPU cumulative mineralization.

Bottom Line: Microbial electroremediating cells (MERCs) consist in a variety of bioelectrochemical devices that aim to overcome electron acceptor limitation and maximize metabolic oxidation with the purpose of enhancing the biodegradation of a pollutant in the environment.The objective of this work was to use MERCs principles for stimulating soil bacteria to achieve the complete biodegradation of the herbicide (14) C-isoproturon (IPU) to (14) CO(2) in soils.The remarkable impact of electrodes on the microbial activity of natural communities suggests a promising future for this emerging environmental technology that we propose to name bioelectroventing.

View Article: PubMed Central - PubMed

Affiliation: University of Alcalá, Alcalá de Henares, Madrid, Spain.

No MeSH data available.


Related in: MedlinePlus