ABSTRACT
Innovative and efficient strategies are urgently needed for wastewater treatment and environmental remediation. The photocatalytic degradation properties of photo-responsive nanomaterials (NMs) have become a prime candidate due to their low negative impact and photo-adjustability. Photocatalytic NMs vary in their degradation of different pollutants depending on the type of synthetic material, excitation light source, and physicochemical properties. Essentially, photocatalytic NMs excited by light produce reactive oxygen species (ROS) or metal ions that can degrade complex structure pollutants. Therefore, this review summarises the recent advances of photocatalytic NMs in the environmental application within the last 3 years, focusing on the development schemes, structural analyses, photocatalytic mechanisms, and the degradation effects of dyes, antibiotics, pesticides, phenolic compounds, metals, hormones, and other contaminants. The limitations and future directions are also explained. This review hopes to provide a possible pathway for the subsequent development of novel and efficient photocatalytic NMs to cope with complex and variable polluted environments.
ABSTRACT
Fresh vegetables are closely associated with foodborne disease outbreaks; however, systematic analysis of the microbiological quality of fresh vegetables and molecular information on foodborne pathogens in fresh produce are poorly reported in China. Here, we evaluated the epidemiological prevalence of coliforms via the most probable number method and characterized Salmonella and ciprofloxacin-resistant (CIPR) Escherichia coli isolates recovered from retail fresh vegetables in Shaanxi Province, China. Antimicrobial susceptibility testing, serotype determination, multilocus sequence typing (MLST), core genome multilocus sequence typing (cgMLST), antibiotic resistance encoding gene (ARG) annotation, virulence factor prediction, and functional classification were performed. Between October 2020 and September 2021, 576 samples (i.e., tomatoes, lettuces, spinaches, and cabbages) were found to be positive for coliforms, and the prevalence of coliforms showed a seasonal trend. Coliform counts of vegetables in supermarkets in Xi'an were significantly lower (P < 0.01) than that in other cities. The detection rates of Salmonella and CIPRE. coli-positive vegetables were 1 % (6/576) and 0.7 % (4/576), respectively. All isolates exhibited resistance to ≥1 antibiotics, and 92.9 % (13/14) were multidrug-resistant. One extended spectrum ß-lactamase (ESBL)-producing CIPRE. coli isolate in spinach was resistant to not only three third-generation cephalosporins but also to two polymyxins. Among nine Salmonella isolates, five different serovars (S. Enteritidis, S. Indiana, monophasic variant of S. Typhimurium, S. Agona, and S. Gallinarum), four sequence types (STs; ST11, ST13, ST17, and ST34), and seven core genome STs (cgSTs) were identified. Five CIPRE. coli strains were assigned to three serovars (O101:H4, O8:H18, and O11:H25), three STs (ST44, ST48, and ST457), and four cgSTs. Coexisting amino acid mutations of Thr57Ser/Ser80Arg in ParC and Ser83Phe/Asp87Gly in GyrA in quinolone resistance-determining regions (QRDRs) might be causes for nalidixic acid resistance. Eight definite virulence profiles in eight serovars were identified. Notably, cdtB and pltA only encoded typhoid toxins and were just detected from S. Typhoid isolates were also detected from S. Indiana and monophasic S. Typhimurium, which are closely associated with swine food chain were first detected in fresh vegetables. In conclusion, our findings suggest that coliform contamination on fresh vegetables is prevalent in this province. Most Salmonella and CIPRE. coli isolates were phenotypically and genetically diverse and could resist multiple antibiotics by carrying multiple ARGs and virulence genes.