Distribution of antibiotic resistance genes in soils and crops. A field study in legume plants (Vicia faba L.) grown under different watering regimes

Abstract

Social concern has raised during the last years due to the development of antibiotic resistance hotspots in different environmental compartments, including the edible parts of crops. To assess the influence of the water quality used for watering, we collected samples from soil, roots, leaves and beans from the legume plant Vicia faba (broad beans) in three agricultural peri-urban plots (Barcelona, NE Spain), irrigated with either groundwater, river water, or reclaimed water. Antibiotic resistance genes (ARGs) sul1, tetM, qnrS1, mecA, and blaTEM were quantified by real-time PCR, along with 16S rDNA and intl1 sequences, as proxies for bacterial abundance and integron prevalence, respectively. Microbiome composition of all samples were analyzed by high-throughput DNA sequencing. Results show a gradient of bacterial species diversity and of ARG prevalence from highly diverse soil samples to microbially-poor beans and leaves, in which Rhizobiales essentially displaced all other groups, and that presented very small loads of ARGs and integron sequences. The data suggest that the microbiome and the associated resistome were likely influenced by agricultural practices and water quality, and that future irrigation water legal standards should consider the specific Physiology of the different crop plants. 2

Towards the Implementation of Circular Economy in the Wastewater Sector: Challenges and Opportunities

“…Wastewater discharges, even after treatment, contains a large number of pollutants potentially dangerous to human health and ecosystems. Some of these pollutants, which are being increasingly analysed and found in reclaimed wastewater [51,52], are pathogens [53], micropollutants [54], antibiotic resistant genes [55], nanomaterials, by-products of disinfection, personal care products, and pharmaceuticals.…”

Tracking antibiotic resistance genes and class 1 integrons in Escherichia coli isolates from wastewater and agricultural fields

“…The presence of intl1 imposes a higher potential for the dissemination of ARGs in the environment. Therefore, the consumption of crops contaminated with bacteria harboring intl1 may trigger a human health risk in terms of exposure to ARGs (Cerqueira et al 2019a).…”

“…Therefore, wastewater reuse for agricultural activities is considered worldwide (Farhadkhani et al 2018). Considering high concentrations of ARB and ARGs in the effluent of WWTPs, agricultural reuse of secondary treated wastewater (STWW) could considerably spread antibiotics, ARB and ARGs into the environment (Cerqueira et al 2019a;Kumar et al 2020). This may lead to an elevated resistance level in microbiome of soil and crops (Cerqueiraet al 2019a(Cerqueiraet al , 2019b, thus threatening human and animal health.…”

“…The increase in AR is facilitated by the association of ARGs with a variety of MGEs (Osinśka et al 2017). Integrons, as one of the genetic elements involved in the environmental spread of AR are found in MGEs such as plasmids and transposons, which promote their spread within bacterial communities (Cerqueira et al 2019a). The common types of integrons which confer resistance to antibiotics including β-lactam antibiotics, chloramphenicol, sulfonamides, aminoglycoside, spectinomycin and others (Su et al 2012) are class 1 integrons.…”

“…In this context, the presence of gram negative bacteria including Enterobacteriaceae members such as Escherichia coli in the environment as important vectors of ARGs, may pose a threat to human health (Cerqueira et al 2019a). E. coli is a commensal bacterium which lives in the gut of humans and warm-blooded animals and could widely spread in different natural environments via feces or treated wastewater (Osinśka et al 2017).…”