Prevalence of Antibiotic Resistance Genes, Heavy Metal Resistance Genes and the Class 1 Integron Gene in Well Water and Tap Water Samples from Four Cities in Henan Province, China

Deciphering the natural and anthropogenic drivers on the fate and risk of antibiotics and antibiotic resistance genes (ARGs) in a typical river-estuary system, China

This study conducts an in-depth assessment of the spatial distribution, ecological risks, and correlations among 12 antibiotics, antibiotic resistance genes (ARGs), and dominant microorganisms in a representative river-estuary system, classified by land use and hydrodynamic conditions. Sulfonamides and quinolones were identified as the major contaminants in surface waters, with aquaculture and healthcare wastewater responsible for over 80 % of the antibiotic load. Contrasting seasonal patterns were observed between freshwater (wet season: 215 ng/L, dry season: 99.9 ng/L) and tidal estuaries (wet season: 45.9 ng/L, dry season: 121 ng/L), attributed to antibiotic transport from terrestrial sources or coastal aquaculture areas. The estimated annual antibiotic influx into Jiaozhou Bay was 70.4 kg/year, posing a considerable threat to aquatic algae and disrupting the stability of aquatic food chain. BugBase predictions suggested that antibiotics in the environment suppressed bacteria characterized by biofilm formation (FB) and the presence of mobile elements (CME). However, ARG transmission was likely to drive the spread of CME, FB, and stress-tolerant (OST) bacteria within microbial communities. The significant positive correlations observed between sulfamethoxazole and 63 microbial genera indicate a broad distribution of microbial resistance, which exacerbates the potential for ARG accumulation and dissemination across both the bay and the Yellow Sea.

The High Risk of Bivalve Farming in Coastal Areas With Heavy Metal Pollution and Antibiotic-Resistant Bacteria: A Chilean Perspective

Anthropogenic pollution has a huge impact on the water quality of marine ecosystems. Heavy metals and antibiotics are anthropogenic stressors that have a major effect on the health of the marine organisms. Although heavy metals are also associate with volcanic eruptions, wind erosion or evaporation, most of them come from industrial and urban waste. Such contamination, coupled to the use and subsequent misuse of antimicrobials in aquatic environments, is an important stress factor capable of affecting the marine communities in the ecosystem. Bivalves are important ecological components of the oceanic environments and can bioaccumulate pollutants during their feeding through water filtration, acting as environmental sentinels. However, heavy metals and antibiotics pollution can affect several of their physiologic and immunological processes, including their microbiome. In fact, heavy metals and antibiotics have the potential to select resistance genes in bacteria, including those that are part of the microbiota of bivalves, such as Vibrio spp. Worryingly, antibiotic-resistant phenotypes have been shown to be more tolerant to heavy metals, and vice versa, which probably occurs through co- and cross-resistance pathways. In this regard, a crucial role of heavy metal resistance genes in the spread of mobile element-mediated antibiotic resistance has been suggested. Thus, it might be expected that antibiotic resistance of Vibrio spp. associated with bivalves would be higher in contaminated environments. In this review, we focused on co-occurrence of heavy metal and antibiotic resistance in Vibrio spp. In addition, we explore the Chilean situation with respect to the contaminants described above, focusing on the main bivalves-producing region for human consumption, considering bivalves as potential vehicles of antibiotic resistance genes to humans through the ingestion of contaminated seafood.

Insights into the associations of copper and zinc with nitrogen metabolism during manure composting with shrimp shell powder

The application of shrimp shell powder (SSP) in manure composting can promote the maturation of compost and reduce the associated environmental risk. This study investigated the response of adding SSP at different levels (CK: 0, L: 5%, M: 10%, and H: 15%) on heavy metal resistance genes (MRGs), nitrogen functional genes, enzymes, and microorganisms. SSP inhibited nitrification and denitrification via decreasing the abundances of functional genes and key enzymes related to Cu, Zn, and MRGs. The nitrate reductase and nitrous-oxide reductase in the denitrification pathway were lower under H. Phylogenetic trees indicated that Burkholderiales sp. had strong relationships with OTU396 and OTU333, with important roles in the nitrogen cycle and plant growth. Redundancy analysis and structural equation modeling showed the complex response between heavy metal and nitrogen that bio-Cu and bio-Zn had positive significantly relationships with nirK-type and amoA-type bacteria, and amoA-type bacteria might be hotspot of cueO.

Spatial behavior and source tracking of extracellular antibiotic resistance genes in a chlorinated drinking water distribution system

Antibiotic resistance genes (ARGs) are receiving increasing concerns due to the antibiotic resistance crisis. Nevertheless, little is known about the spatial behavior and sources of extracellular ARGs (eARGs) in the chlorinated drinking water distribution systems (DWDSs). Here, tap water was continuously collected to reveal the occurrence of both eARGs and intracellular ARGs (iARGs) along a chlorinated DWDS. Afterward, the correlation between eARGs, eDNA-releasing communities, and communities of planktonic bacteria was further analyzed. The eARG concentration decreased significantly, whereas the proportion of vanA and bla_NDM-1 increased. Further, the diversity of the eDNA-releasing community increased markedly with increasing distance from the drinking water treatment plant (DWTP). Moreover, the dominant eDNA-releasing bacteria shifted from Acinetobacter, Pseudomonas, and Methylobacterium-Methylorubrum in finished water from the DWTP to Bacteroides, Faecalibacterium, Staphylococcus, and Parabacteroides in the DWDS. In terms of eARG source, thirty genera were significantly correlated with seven types of eARGs that resulted from the lysis of dead planktonic bacteria and detached biofilms. Conversely, the iARGs concentration increased, whereas the biodiversity of the planktonic bacteria community decreased in the sampling points along the DWDSs. Our findings provide critical insights into the spatial behavior and sources of eARGs, highlighting the health risks associated with ARGs in DWDSs.