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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 erm(B), intI1, sul1, tet(A), tet(W), and tet(X) in residual solids undergoing batch treatment. Values are the arithmetic mean of triplicate samples; error bars represent one standard deviation.
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Figure 5: The quantities of erm(B), intI1, sul1, tet(A), tet(W), and tet(X) in residual solids undergoing batch treatment. Values are the arithmetic mean of triplicate samples; error bars represent one standard deviation.

Mentions: In contrast to operation in semi-continuous flow mode, the quantities of all of the antibiotic resistance determinants, including intI1 and tet(X), declined in the batch experimental phase (Figure 5). The quantities of erm(B) and tet(W) declined by approximately two orders of magnitude during the 20-day experiment, whereas the quantities of intI1, sul1, tet(A), and tet(X) each declined by one order of magnitude during the same time period. Correspondingly, the first-order decay rates varied considerably among individual gene targets. The intI1 and tet(X) genes decayed the most slowly, each with a half-life of approximately 6 days (Table 3). These rates of decay were statistically similar to each other as well as to the rate of decay for the 16S rRNA gene (Table 4). In contrast, the first-order decay rates were significantly (P < 0.05) more rapid for the remaining gene targets, with half-lives ranging from 2.8 to 4.6 days (Table 3). These rates of decay were significantly faster than the decay rate for 16S rRNA genes (Table 4).


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 erm(B), intI1, sul1, tet(A), tet(W), and tet(X) in residual solids undergoing batch treatment. 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 5: The quantities of erm(B), intI1, sul1, tet(A), tet(W), and tet(X) in residual solids undergoing batch treatment. Values are the arithmetic mean of triplicate samples; error bars represent one standard deviation.
Mentions: In contrast to operation in semi-continuous flow mode, the quantities of all of the antibiotic resistance determinants, including intI1 and tet(X), declined in the batch experimental phase (Figure 5). The quantities of erm(B) and tet(W) declined by approximately two orders of magnitude during the 20-day experiment, whereas the quantities of intI1, sul1, tet(A), and tet(X) each declined by one order of magnitude during the same time period. Correspondingly, the first-order decay rates varied considerably among individual gene targets. The intI1 and tet(X) genes decayed the most slowly, each with a half-life of approximately 6 days (Table 3). These rates of decay were statistically similar to each other as well as to the rate of decay for the 16S rRNA gene (Table 4). In contrast, the first-order decay rates were significantly (P < 0.05) more rapid for the remaining gene targets, with half-lives ranging from 2.8 to 4.6 days (Table 3). These rates of decay were significantly faster than the decay rate for 16S rRNA genes (Table 4).

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