Antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) are widespread in urban wastewater treatment plants (UWTPs). In this research, a horizontal transfer model of recipient ( Pseudomonas . HLS-6) and donor ( Escherichia coli DH5α carries RP4 plasmid) was constructed to explore the effect of sulfidated nanoscale zerovalent iron (S-nZVI) on the efficiency of plasmid-mediated horizontal transfer. When the S/Fe was 0.1, the inactivation efficiency of 1120 mg/L S-nZVI on the donor and recipient bacteria were 2.36 ± 0.03 log and 3.50 ± 0.17 log after 30 min, respectively (initial ARB concentration ≈ 5 ×10 7 CFU/mL). Effects of treatment time, S/Fe molar ratio, S-nZVI dosage and initial bacterial concentration were systemically studied. S-nZVI treatment could increase the extracellular alkaline phosphatase and malondialdehyde content of the ARB, cause oxidative stress in the bacteria, destroy the cell structure and damage the intracellular DNA. This study provided evidence and insights into possible underlying mechanisms for reducing conjugative transfer, such as hindering cell membrane repair, inducing the overproduction of reactive oxygen species , inhibiting the SOS response, reducing the expression of ARGs and related transfer genes. S-nZVI could inhibit the gene conjugative transfer while inactivating the ARB. The findings provided an alternative method for controlling antibiotic resistance.
Environmental antibiotics raise serious health concerns due to their contribution to the obesity prevalence. Moreover, antibiotics promote antibiotic-resistance bacteria (ARB) which represent another emerging pollutant. However, the interaction between antibiotic and ARB in the obesogenic effects remained unexplored. In the present study, the obesogenic effects of tetracycline antibiotic (TCH) and ARB containing tetA were studied on C . elegans , and E . coli OP50 (OP50) was referred as a normal bacterial food. Results showed that TCH stimulated nematode triglyceride contents, while ARB alone had no significant influences. The combination of TCH and ARB showed less obesogenic effects than TCH alone, showing antagonism. Biochemical assays showed that the combination of TCH and ARB showed similar effects to ARB alone, and had less increases in lipid metabolism enzymes or metabolites than those of TCH or ARB alone, supporting the antagonism. In the nontargeted metabolomic analysis, TCH with ARB showed less significantly changed metabolites (SCMs) in the nematodes than TCH or ARB alone, partially explaining the antagonism. The metabolomic results also pointed out the significant involvement of amino acids, the carboxylic acids and derivatives, and also the benzene and substituted derivatives in the obesogenic effects of TCH and ARB. The findings of the present study provided a direct support for interaction between antibiotics and ARB underlying their health risks.
Boru Gao,Mengmeng Dou,Jin Wang,Shuming Li,Dongying Wang,Lin Ci,Yao Fu
Contaminants such as antibiotics and the resulting antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) have become a hot topic in the field of wastewater purification. In this study, a method was proposed to simultaneously remove antibiotics and reduce ARB and ARGs with C–(N) 3 defect carbon nitride-coupled persulfates (CN-C V2 /PS). The location of the C–(N) 3 defects was determined by a combination of spectroscopic techniques and electron spin resonance tests. Based on photoluminescence and electrochemical tests, and deformation charge density calculations, electron traps were generated at defect sites resulting in enhanced electron–hole separation. The mineralization rates of CN-C V2 /PS for six typical antibiotics were 11–17% and 21–28% higher than those of CN-C V2 and conventional CN , respectively. Over the same reaction time, the inactivation rates of CN-C V2 /PS for E. coli and E. faecalis screened from wastewater treatment plants were 3.6 and 2.7 log higher than that of CN-C V2 . In addition, CN-C V2 /PS showed a reduction rate of more than 2.5 log for tet A and intI 1. DFT calculation showed that due to the formation of defects, the adsorption energy between the PS and catalysts increased from –8.924 eV (CN) to –18.340 eV (CN-C V2 ). At the same time, the effective stretch of peroxide bond of PS changed from 1.505 Å to 1.519 Å. Both results indicated that the activation of PS was significantly enhanced in the presence of the modified CN-C V2 . The synergetic effect of CN-C V2 /PS is expected to remove the antibiotics, resistant bacteria and genes efficiently in future wastewater advanced treatment.
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