Per-and polyfluoroalkyl substances (PFAS) are widely used industrial chemicals that are of a great concern because of their pervasive presence in water resources and association with negative health effects. Crosslinked β-cyclodextrin-containing (β-CD) polymer adsorbents have shown promising performances for sequestering PFAS. Recently, installing amino groups into the crosslinkers of a β-CD polymer network improved the binding of many anionic PFAS, including short-chain and branched derivatives. However, the relative importance of the electrostatic interactions from the amino groups and the host-guest interactions within the cavity of the β-CD for PFAS binding are unclear. Herein, β-CD-based adsorbents crosslinked with tripodal crosslinkers containing three amino or amido groups are prepared with comparable physicochemical properties to investigate the respective roles of the crosslinker and β-CD in binding affinity and capacity for anionic PFAS. β-CD polymers containing amines showed superior removal for ten anionic PFAS compared to polymers containing amido groups. Both β-CD polymers have superior performance for perfluorooctanoic acid (PFOA) removal compared to activated carbons (ACs), consistent with β-CD:PFOA inclusion complexes playing an important role. Adsorbents containing amido groups showed low binding affinity and capacity for GenX, whereas the amine-functionalized polymer had outstanding affinity and capacity for GenX (K L = 8.8 × 10 4 M −1 , Q M = 222 mg g −1 ), underscoring the essential role of electrostatic interactions for removing short-chain and branched PFAS. The amine-containing β-CD polymer exhibited 100-fold higher affinity and twice the capacity (K L = 1.8 × 10 6 M −1 , Q M = 457 mg g −1 ) for PFOA compared to GenX, which are the highest reported values for β-CD polymers. These results highlight the synergistic effects of electrostatic interactions and host-guest interactions in β-CD polymers as important design criteria for efficient removal of anionic PFAS from water. This study further demonstrates broad tunability of crosslinked β-CD polymers and their promise as adsorbents for PFAS remediation.
Infections resistant to broad spectrum antibiotics due to the emergence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae is of global concern. This study characterizes the resistome (i.e., entire ecology of resistance determinants) of 11 ESBL-producing Escherichia coli isolates collected from eight wastewater treatment utilities across Oregon. Whole genome sequencing was performed to identify the most abundant antibiotic resistance genes including ESBL-associated genes, virulence factors, as well as their sequence types. Moreover, the phenotypes of antibiotic resistance were characterized. ESBL-associated genes (i.e., blaCMY, blaCTX, blaSHV, blaTEM) were found in all but one of the isolates with five isolates carrying two of these genes (four with blaCTX and blaTEM; one with blaCMY and blaTEM). The ampC gene and virulence factors were present in all the E. coli isolates. Across all the isolates, 31 different antibiotic resistance genes were identified. Additionally, all E. coli isolates harbored phenotypic resistance to beta-lactams (penicillins and cephalosporins), while 8 of the 11 isolates carried multidrug resistance phenotypes (resistance to three or more classes of antibiotics). Findings highlight the risks associated with the presence of ESBL-producing E. coli isolates in wastewater systems that have the potential to enter the environment and may pose direct or indirect risks to human health.
Infections resistant to broad spectrum antibiotics due to the emergence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae is of global concern. This study characterizes the resistome (i.e., entire ecology of resistance determinants) of 11 ESBL-producing Escherichia coli isolates collected from eight wastewater treatment utilities across Oregon. Whole genome sequencing was performed to identify the most abundant antibiotic resistance genes including ESBL-associated genes, virulence factors, as well as their sequence types. Moreover, the phenotypes of antibiotic resistance were characterized. ESBL-associated genes (i.e., blaCMY, blaCTX, blaSHV, blaTEM) were found in all but one of the isolates with five isolates carrying two of these genes (4 with blaCTX and blaTEM; 1 with blaCMY and blaTEM). The ampC gene and virulence factors were present in all the E. coli isolates. Across all the isolates, 31 different antibiotic resistance genes were identified. Additionally, all E. coli isolates harbored phenotypic resistance to beta-lactams (penicillins and cephalosporins), while eight of the 11 isolates carried multi-drug resistance phenotypes (resistance to three or more classes of antibiotics). Findings highlight the risks associated with the presence of ESBL-producing E. coli isolates in wastewater systems that have the potential to enter the environment and may pose direct or indirect risks to human health.
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