The mixture toxicity of environmental contaminants containing sulfonamides and other antibiotics in Escherichia coli: Differences in both the special target proteins of individual chemicals and their effective combined concentration
“…While the chronic test takes 24 h, during which the bacteria grow from extremely low density to high density (stationary phase), as shown in Figure S1 in the supporting information. During this period, the antibiotics could on the one hand bind with their target proteins 26 (DHPS, DHFR and 16S rRNA, respectively), killing or inhibiting the bacterial growth, on the other hand affect the bacterial QS communications (see Figure S2 for detailed information on QS of V . fischeri ).Figure 3Mechanisms for the acute and chronic toxicity of individual chemicals.…”
Section: Resultsmentioning
confidence: 99%
“…As noted in the study of Long et al . 26 , TCs can inhibit the protein synthesis and decrease the amount of intracellular DHPS or DHFR accordingly, which led to the decrease of the acting sites of SAs or SAPs and thus weakened their toxicity.…”
Section: Resultsmentioning
confidence: 99%
“…In this equation, and represented the acute EC 50 s of component A and B, while and denoted the chronic EC 50 s. The parameter indicated the apparent concentration proportion of component i in the mixtures, which was proposed by Zou et al . 19 and have been introduced for the QSTR model constructions for mixtures 26, 31 . This parameter was involved in this model to reflect the varying contribution of drug i in different mixtures.…”
The determination of the chronic toxicity is time-consumed and costly, so it’s of great interest to predict the chronic toxicity based on acute data. Current methods include the acute to chronic ratios (ACRs) and the QSTR models, both of which have some usage limitations. In this paper, the acute and chronic mixture toxicity of three types of antibiotics, namely sulfonamides, sulfonamide potentiators and tetracyclines, were determined by a bioluminescence inhibition test. A novel QSTR model was developed for predicting the chronic mixture toxicity using the acute data and docking-based descriptors. This model revealed a complex relationship between the acute and chronic toxicity, i.e. a linear correlation between the acute and chronic lg(−lgEC50)s, rather than the simple EC50s or −lgEC50s. In particular, the interaction energies (Ebind) of the chemicals with luciferase and LitR in the bacterial quorum sensing systems were introduced to represent their acute and chronic actions, respectively, regardless of their defined toxic mechanisms. Therefore, the present QSTR model can apply to the chemicals with distinct toxic mechanisms, as well as those with undefined mechanism. This study provides a novel idea for the acute to chronic toxicity extrapolation, which may benefit the environmental risk assessment on the pollutants.
“…While the chronic test takes 24 h, during which the bacteria grow from extremely low density to high density (stationary phase), as shown in Figure S1 in the supporting information. During this period, the antibiotics could on the one hand bind with their target proteins 26 (DHPS, DHFR and 16S rRNA, respectively), killing or inhibiting the bacterial growth, on the other hand affect the bacterial QS communications (see Figure S2 for detailed information on QS of V . fischeri ).Figure 3Mechanisms for the acute and chronic toxicity of individual chemicals.…”
Section: Resultsmentioning
confidence: 99%
“…As noted in the study of Long et al . 26 , TCs can inhibit the protein synthesis and decrease the amount of intracellular DHPS or DHFR accordingly, which led to the decrease of the acting sites of SAs or SAPs and thus weakened their toxicity.…”
Section: Resultsmentioning
confidence: 99%
“…In this equation, and represented the acute EC 50 s of component A and B, while and denoted the chronic EC 50 s. The parameter indicated the apparent concentration proportion of component i in the mixtures, which was proposed by Zou et al . 19 and have been introduced for the QSTR model constructions for mixtures 26, 31 . This parameter was involved in this model to reflect the varying contribution of drug i in different mixtures.…”
The determination of the chronic toxicity is time-consumed and costly, so it’s of great interest to predict the chronic toxicity based on acute data. Current methods include the acute to chronic ratios (ACRs) and the QSTR models, both of which have some usage limitations. In this paper, the acute and chronic mixture toxicity of three types of antibiotics, namely sulfonamides, sulfonamide potentiators and tetracyclines, were determined by a bioluminescence inhibition test. A novel QSTR model was developed for predicting the chronic mixture toxicity using the acute data and docking-based descriptors. This model revealed a complex relationship between the acute and chronic toxicity, i.e. a linear correlation between the acute and chronic lg(−lgEC50)s, rather than the simple EC50s or −lgEC50s. In particular, the interaction energies (Ebind) of the chemicals with luciferase and LitR in the bacterial quorum sensing systems were introduced to represent their acute and chronic actions, respectively, regardless of their defined toxic mechanisms. Therefore, the present QSTR model can apply to the chemicals with distinct toxic mechanisms, as well as those with undefined mechanism. This study provides a novel idea for the acute to chronic toxicity extrapolation, which may benefit the environmental risk assessment on the pollutants.
“…Step 2: In TU method, the joint toxic action of antibacterial agents could be judged to be antagonism, addition, or synergism via comparing TU value with 0.8 and 1.2 [ 21 , 22 ]. Similarly, the joint resistance action of antibacterial agents could be judged as follows: when MU ( CTU ) < 0.8, the joint action of components on the promotion of mutation frequency (conjugative transfer frequency) was synergism; when 0.8 ≤ MU ( CTU ) ≤ 1.2, the joint action of components on the promotion of mutation frequency (conjugative transfer frequency) was addition; and when MU ( CTU ) > 1.2, the joint action of components on the promotion of mutation frequency (conjugative transfer frequency) was antagonism.…”
“…This situation can lead to the deposition of large quantities of antibiotic residue in water and soil sediments, and this deposition causes serious harm to microorganisms or other non‐target creatures . Antibiotics are recognized as a class of potential environment‐threatening pollutants because antibiotic residues cause significant ecological damage …”
Wastewater treatment cannot effectively remove tetracycline contained in wastewater, and environmental residues accumulate as a result of this condition. Existing methods use to address the high cost of wastewater treatment and other economic and effective means have been explored. Aerobic granular sludge technology is a newly developed potential biological wastewater treatment method, but the removal of tetracycline through this process is limited. Therefore, the collection of tetracycline‐degrading bacteria as a biological fortifier is vital. In this experiment, 20 and 24 tetracycline‐degrading bacteria are isolated from granular and activated sludge samples, respectively. Highly efficient tetracycline‐degrading strains are selected. The effect of these strains on the degradation rate is investigated under the influence of different factors, namely, time, pH, extra carbon source, inoculum concentration of extra nitrogen source, and substrate concentration. Determination of the nucleotide sequence of the gene encoding for 16S rRNA and physiological and biochemical identification shows that two strains belonged to Achromobacter species.
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