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Aerobic digestion reduces the quantity of antibiotic resistance genes in residual municipal wastewater solids.

Burch TR, Sadowsky MJ, Lapara TM - Front Microbiol (2013)

Bottom Line: Numerous initiatives have been undertaken to circumvent the problem of antibiotic resistance, including the development of new antibiotics, the use of narrow spectrum antibiotics, and the reduction of inappropriate antibiotic use.During this time, the quantities of tet(A), tet(W), and erm(B) decreased by more than 90%.In contrast, intI1 did not decrease, and tet(X) increased in quantity by 5-fold.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil Engineering, University of Minnesota Minneapolis, MN, USA.

ABSTRACT
Numerous initiatives have been undertaken to circumvent the problem of antibiotic resistance, including the development of new antibiotics, the use of narrow spectrum antibiotics, and the reduction of inappropriate antibiotic use. We propose an alternative but complimentary approach to reduce antibiotic resistant bacteria (ARB) by implementing more stringent technologies for treating municipal wastewater, which is known to contain large quantities of ARB and antibiotic resistance genes (ARGs). In this study, we investigated the ability of conventional aerobic digestion to reduce the quantity of ARGs in untreated wastewater solids. A bench-scale aerobic digester was fed untreated wastewater solids collected from a full-scale municipal wastewater treatment facility. The reactor was operated under semi-continuous flow conditions for more than 200 days at a residence time of approximately 40 days. During this time, the quantities of tet(A), tet(W), and erm(B) decreased by more than 90%. In contrast, intI1 did not decrease, and tet(X) increased in quantity by 5-fold. Following operation in semi-continuous flow mode, the aerobic digester was converted to batch mode to determine the first-order decay coefficients, with half-lives ranging from as short as 2.8 days for tet(W) to as long as 6.3 days for intI1. These results demonstrated that aerobic digestion can be used to reduce the quantity of ARGs in untreated wastewater solids, but that rates can vary substantially depending on the reactor design (i.e., batch vs. continuous-flow) and the specific ARG.

No MeSH data available.


Related in: MedlinePlus

The quantities of intI1 and tet(X) in untreated (closed circles) and treated (open circles) residual solids. Values are the arithmetic mean of triplicate samples; error bars represent one standard deviation.
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Figure 3: The quantities of intI1 and tet(X) in untreated (closed circles) and treated (open circles) residual solids. Values are the arithmetic mean of triplicate samples; error bars represent one standard deviation.

Mentions: The bench-scale aerobic digester removed between 85 and 98% of erm(B), sul1, tet(A), and tet(W) during the semi-continuous flow experimental period (Figure 2), which was substantially greater than that for bacterial biomass (i.e., 16S rRNA genes). In contrast, the quantity of intI1 was not statistically different (P = 0.17) in the untreated and treated solids, suggesting that aerobic digestion operated in semi-continuous flow mode does not eliminate intI1 (Figure 3). Furthermore, the ratio of intI1 to 16S rRNA genes increased in the treatment process from 0.8 to 3%, indicating that aerobic digestion likely selects for bacterial cells possessing a class 1 integron. Interestingly, the aerobic digestion process also appeared to select for bacterial cells containing tet(X), as the quantity of this gene was 5-fold greater in the treated solids than in the untreated solids.


Aerobic digestion reduces the quantity of antibiotic resistance genes in residual municipal wastewater solids.

Burch TR, Sadowsky MJ, Lapara TM - Front Microbiol (2013)

The quantities of intI1 and tet(X) in untreated (closed circles) and treated (open circles) residual solids. Values are the arithmetic mean of triplicate samples; error bars represent one standard deviation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3569665&req=5

Figure 3: The quantities of intI1 and tet(X) in untreated (closed circles) and treated (open circles) residual solids. Values are the arithmetic mean of triplicate samples; error bars represent one standard deviation.
Mentions: The bench-scale aerobic digester removed between 85 and 98% of erm(B), sul1, tet(A), and tet(W) during the semi-continuous flow experimental period (Figure 2), which was substantially greater than that for bacterial biomass (i.e., 16S rRNA genes). In contrast, the quantity of intI1 was not statistically different (P = 0.17) in the untreated and treated solids, suggesting that aerobic digestion operated in semi-continuous flow mode does not eliminate intI1 (Figure 3). Furthermore, the ratio of intI1 to 16S rRNA genes increased in the treatment process from 0.8 to 3%, indicating that aerobic digestion likely selects for bacterial cells possessing a class 1 integron. Interestingly, the aerobic digestion process also appeared to select for bacterial cells containing tet(X), as the quantity of this gene was 5-fold greater in the treated solids than in the untreated solids.

Bottom Line: Numerous initiatives have been undertaken to circumvent the problem of antibiotic resistance, including the development of new antibiotics, the use of narrow spectrum antibiotics, and the reduction of inappropriate antibiotic use.During this time, the quantities of tet(A), tet(W), and erm(B) decreased by more than 90%.In contrast, intI1 did not decrease, and tet(X) increased in quantity by 5-fold.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil Engineering, University of Minnesota Minneapolis, MN, USA.

ABSTRACT
Numerous initiatives have been undertaken to circumvent the problem of antibiotic resistance, including the development of new antibiotics, the use of narrow spectrum antibiotics, and the reduction of inappropriate antibiotic use. We propose an alternative but complimentary approach to reduce antibiotic resistant bacteria (ARB) by implementing more stringent technologies for treating municipal wastewater, which is known to contain large quantities of ARB and antibiotic resistance genes (ARGs). In this study, we investigated the ability of conventional aerobic digestion to reduce the quantity of ARGs in untreated wastewater solids. A bench-scale aerobic digester was fed untreated wastewater solids collected from a full-scale municipal wastewater treatment facility. The reactor was operated under semi-continuous flow conditions for more than 200 days at a residence time of approximately 40 days. During this time, the quantities of tet(A), tet(W), and erm(B) decreased by more than 90%. In contrast, intI1 did not decrease, and tet(X) increased in quantity by 5-fold. Following operation in semi-continuous flow mode, the aerobic digester was converted to batch mode to determine the first-order decay coefficients, with half-lives ranging from as short as 2.8 days for tet(W) to as long as 6.3 days for intI1. These results demonstrated that aerobic digestion can be used to reduce the quantity of ARGs in untreated wastewater solids, but that rates can vary substantially depending on the reactor design (i.e., batch vs. continuous-flow) and the specific ARG.

No MeSH data available.


Related in: MedlinePlus