Biodiversity of organisms inhabiting the water supply network of Wroclaw. Detection of pathogenic organisms constituting a threat for drinking water recipients

Assessing Antibiotic-Resistant Genes in University Dormitory Washing Machines

University dormitories represent densely populated environments, and washing machines are potential sites for the spread of bacteria and microbes. However, the extent of antibiotic resistance gene (ARG) variation in washing machines within university dormitories and their potential health risks are largely unknown. To disclose the occurrence of ARGs and antibiotic-resistant bacteria from university dormitories, we collected samples from washing machines in 10 dormitories and used metagenomic sequencing technology to determine microbial and ARG abundance. Our results showed abundant microbial diversity, with Proteobacteria being the dominant microorganism that harbors many ARGs. The majority of the existing ARGs were associated with antibiotic target alteration and efflux, conferring multidrug resistance. We identified tnpA and IS91 as the most abundant mobile genetic elements (MGEs) in washing machines and found that Micavibrio aeruginosavorus, Aquincola tertiaricarbonis, and Mycolicibacterium iranicum had high levels of ARGs. Our study highlights the potential transmission of pathogens from washing machines to humans and the surrounding environment. Pollution in washing machines poses a severe threat to public health and demands attention. Therefore, it is crucial to explore effective methods for reducing the reproduction of multidrug resistance.

MXene@Au based electrochemical biosensor with pretreatment by magnetic nanoparticles for determination of MRSA from clinical samples

Pathogenic bacteria are associated with high morbidity rates and present significant diagnostic challenges in terms of rapid detection. This study introduces a magnetic separation-based electrochemical biosensor for the detection of Methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin (Van) was used to modify on the surface of polyethyleneimine (PEI) mediated MBs (MBs-PEI-Van) for separation and enrichment of MRSA. The MBs-PEI-Van shown a satisfactory stability and applicability with capture effective (CE) > 85% in both PBS and cerebrospinal fluid (CSF) samples. MXene@Au with controllable size of AuNPs was synthesized by a self-reduction method and employed to modify the glassy carbon electrode (GCE). Immunoglobulin G (IgG) was loaded onto the modified electrode to immobilize MRSA, and ferroceneboronic acid (Fc-BA) was used as a probe for quantitative determination. The differential pulse voltammetry (DPV) current was plotted against the concentration of MRSA from 3.8 × 101 to 3.8 × 107 CFU/mL with a limit of detection (LOD) of 3.8 × 101 CFU/mL. In addition, MRSA was successfully detected in spiked CSF samples with satisfactory recoveries (94.35-107.81 %) and validation results (RSD < 11 %). Overall, this study presents a promising method for the detection of MRSA, with the potential to be further developed into a universal pathogen detection method.

Community Composition and Antibiotic Resistance of Tap Water Bacteria Retained on Filtration Membranes

Community composition and antibiotic resistance of tap water bacteria are still not known well enough. This study fills the gaps in knowledge regarding this matter. To provide representativeness of collected samples, tap water bacteria were concentrated from huge amounts of water, using filtration membranes monthly during the continuous, semi-annual study, covering winter and spring seasons. Biomass was investigated both using a culture-based method (for total and antibiotic-resistant culturable bacteria counts) and metagenomic DNA sequencing (for taxonomic identification of bacteria). The results showed that bacteria resistant to ceftazidime were the most prevalent among the studied resistance phenotypes, whereas bacteria resistant to amoxicillin, ciprofloxacin, and tetracycline were scarce. On average, 20,059 and 26,200 CFU/mL per month was counted in the winter and spring season, respectively, whereas in terms of antibiotic-resistant bacteria, average counts were 14,270 and 9435 CFU/mL per month in the winter and spring season, respectively. In terms of bacterial community composition, Cyanobacteria, Proteobacteria and Actinobacteria were the most abundant phyla, reaching up to 77.71%, 74.40% and 21.85%, respectively, which is supported by previous studies conducted on the same water supply network and other drinking water distribution systems across the world. No season-dependent variations were observed for culturable antibiotic-resistant bacteria or bacterial community composition. The prevalence of culturable antibiotic-resistant bacteria was not correlated with any of the identified taxa.

Analyzing the Relationship between Hotel Brand Image, Service Quality, Experience Marketing, and Customer Satisfaction under the Environment of Social Network

Based on the development background of the social network environment, higher requirements are put forward for the development and transformation of hotels in the new era. As a representative industry in the service industry, the service quality and experience provided by the hotel can meet the feelings and needs of customers. According to the data of the hotel industry in previous years, it can be found that from 2015 to 2018, the average revenue of hotel rooms available for rent (RevPAR) decreased by 7.7%, 5.3%, and 7.7%, respectively; The occupancy rate dropped to the lowest point at the end of 2018 and then began to rise gradually. In addition, while the economy recovers, the tourism industry has driven the hotel industry. RevPAR has increased by—1.4% and 3.5% year-on-year, and the occupancy rate has increased by 3.6% and 2.0% year-on-year. In 2018, China's star hotels generally showed an upward trend. This also shows the attraction of hotel brand logo to customers. By studying the factors such as brand image and service quality, we can establish the viscosity with customers. This paper explores the relationship between various elements and customers and puts forward effective suggestions in order to further improve the service level of the hotel.

Microbiomes in drinking water treatment and distribution: A meta-analysis from source to tap

A meta-analysis of existing and available Illumina 16S rRNA datasets from drinking water source, treatment and drinking water distribution systems (DWDS) were collated to compare changes in abundance and diversity throughout. Samples from bulk water and biofilm were used to assess principles governing microbial community assembly and the value of amplicon sequencing to water utilities. Individual phyla relationships were explored to identify competitive or synergistic factors governing DWDS microbiomes. The relative importance of stochasticity in the assembly of the DWDS microbiome was considered to identify the significance of source and treatment in determining communities in DWDS. Treatment of water significantly reduces overall species abundance and richness, with chlorination of water providing the most impact to individual taxa relationships. The assembly of microbial communities in the bulk water of the source, primary treatment process and DWDS is governed by more stochastic processes, as is the DWDS biofilm. DWDS biofilm is significantly different from bulk water in terms of local contribution to beta diversity, type and abundance of taxa present. Water immediately post chlorination has a more deterministic microbial assembly, highlighting the significance of this process in changing the microbiome, although elevated levels of stochasticity in DWDS samples suggest that this may not be the case at customer taps. 16S rRNA sequencing is becoming more routine, and may have several uses for water utilities, including: detection and risk assessment of potential pathogens such as those within the genera of Legionella and Mycobacterium; assessing the risk of nitrification in DWDS; providing improved indicators of process performance and monitoring for significant changes in the microbial community to detect contamination. Combining this with quantitative methods like flow cytometry will allow a greater depth of understanding of the DWDS microbiome.

Microbial communities of biofilms developed in a chlorinated drinking water distribution system: A field study of antibiotic resistance and biodiversity

Antibiotic resistance and biodiversity were investigated in microbial communities attached to inner surfaces of water supply fittings in a chlorinated drinking water distribution system (DWDS) supplied by two independent water treatment plants (WTPs) drawing the same source water. The investigation of the effect of the season, the applied water treatment technology, and type, material, and age of water supply fittings on both antibiotic resistance and biodiversity in biofilms involved collection of tubercles during summer and winter seasons throughout the DWDS. A total of 16 samples were collected (8 per season) from areas supplied by two independent WTPs. Culturable aerobic antibiotic resistant bacteria (ARB) proved more prevalent in summer. Various antibiotic resistance genes (ARGs) were detected, confirming the role of biofilms as ARGs reservoirs, but the abundances of quantified genes (sulI, ermB, qacEΔ1, intI1) were low (a range of <LOQ to 2313 gene copies/mg dry mass of tubercles) throughout the DWDS. In terms of microbial community composition, Proteobacteria were dominant in each sample (51.51-97.13%), and the most abundant genus was Desulfovibrio (0.01-66.69%) belonging to sulphate-reducing bacteria. Biodiversity of microbial communities was shaped by many coexisting factors, including season, water supply fitting material, and sampling site location. Spatial distribution analysis revealed that although only samples collected at the same sampling sites were similar to each other in terms of antibiotic resistance, some samples collected in the close proximity were similar in terms of biodiversity. This suggests that antibiotic resistance spreads only locally over small distances in drinking water biofilms. Although actual drinking water biofilms have been previously investigated in terms of microbial biodiversity, this is the first study that characterised both antibiotic resistance and biodiversity of microbial communities attached to inner surfaces of a real DWDS functioning for decades.

Fate of antibiotics and antibiotic resistance genes in home water purification systems

Home water purification systems (HWPSs) are utilized worldwide to obtain clean drinking water. However, the reliability of HWPSs in providing safe water is unknown or not well-proven. In this study, the occurrences of antibiotics and antibiotic resistance genes (ARGs) in tap water, effluents, and filters of HWPSs were investigated in twenty-six houses and one laboratory. The levels of antibiotics and ARGs were between less than the limit of detection (LOD) and 7.9 ng/L and between less than LOD and 3.45 × 10⁵ copies/L, respectively, in tap water. HWPSs with fresh filters had a high efficiency in removing antibiotics and ARGs, with removal rates of 91-92% and 0.46-2.43 log, respectively. However, after long-term operation (e.g., more than three months), some HWPSs had low removal rates of antibiotics and ARGs (3-79% and 0.03-0.15 log, respectively) and some HWPSs released antibiotics and ARGs into the effluents leading to higher levels of antibiotics and ARGs in the effluents than those in the influents. Biofilms were observed on many filters of the investigated HWPSs. ARGs were detected on the filters with relative abundances (the ratio of the abundance of ARGs to the abundance of 16S rRNA) of 2.56 × 10^-8-2.89 × 10^-2. High-throughput sequencing analysis showed that Proteobacteria, Acidobacteria, Chloroflexi, and Bacteroidetes were the dominant phyla, and Alphaproteobacteria and Gammaproteobacteria were the dominant classes. The abundances of Cyanobacteria, Patescibacteria, Bacteroidetes, and Proteobacteria were significantly positively correlated with the abundances of ARGs. Microbial growth and enrichment commonly observed in HWPSs can accelerate the exposure risk posed by antibiotics and ARGs to the consumers of water from these appliances.

The microbial ecology of a Mediterranean chlorinated drinking water distribution systems in the city of Valencia (Spain)

Drinking water distribution systems host extensive microbiomes with diverse biofilm communities regardless of treatment, disinfection, or operational practices. In Mediterranean countries higher temperatures can accelerate reactions and microbial growth that may increase aesthetic water quality issues, particularly where material deposits can develop as a result of net zero flows within looped urban networks. This study investigated the use of flow and turbidity monitoring to hydraulically manage mobilisation of pipe wall biofilms and associated material from the Mediterranean city of Valencia (Spain). Pipe sections of different properties were subjected to controlled incremental flushing with monitoring and sample collection for physico-chemical and DNA analysis with Illumina sequencing of bacterial and fungal communities. A core microbial community was detected throughout the network with microorganisms like Pseudomonas, Aspergillus or Alternaria increasing during flushing, indicating greater abundance in underlying and more consolidated material layers. Bacterial and fungal communities were found to be highly correlated, with bacteria more diverse and dynamic during flushing whilst fungi were more dominant and less variable between sampling sites. Results highlight that water quality management can be achieved through hydraulic strategies yet understanding community dynamics, including the fungal component, will be key to maintaining safe and ultimately beneficial microbiomes in drinking water distribution systems.

Spatiotemporal Changes of Antibiotic Resistance and Bacterial Communities in Drinking Water Distribution System in Wrocław, Poland

Antibiotic resistance of bacteria is an emerging problem in drinking water treatment. This paper presents the comparison of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) prevalence during the summer and winter season in a full-scale drinking water distribution system (DWDS) supplied by two water treatment plants (WTPs). The effect of distance from WTP and physical–chemical water parameters on its microbial properties was also tested. Bacterial consortia dwelling in bulk tap water were additionally compared by means of denaturating gradient gel electrophoresis (DGGE). The results showed that among ARB, bacteria resistant to ceftazidime (CAZ) were the most abundant, followed by bacteria resistant to amoxicillin (AML), ciprofloxacin (CIP), and tetracycline (TE). Numerous ARGs were detected in tested tap water samples. Only CAZ resistant bacteria were more prevalent in the season of increased antibiotic consumption, and only AML resistant bacteria relative abundances increase was statistically significant with the distance from a WTP. The investigated tap water meets all legal requirements. It is therefore safe to drink according to the law. Nevertheless, because antibiotic resistance could pose a threat to consumer health, it should be further monitored in DWDSs.

Seasonal variability of chemical composition and mutagenic effect of organic PM2.5 pollutants collected in the urban area of Wrocław (Poland)

The objective of the study was the assessment of the mutagenicity of chemical pollutants adsorbed on suspended particulate matter with aerodynamic diameter < 2.5 μm (PM2.5) in the four seasons. Samples were collected from the urban agglomeration of Wroclaw, Poland and evaluated for mutagenicity using two Salmonella typhimurium strains TA98 and TA100 with and without metabolic activation with microsomal fraction S9. The work covered sampling of suspended dusts in four seasons: summer, spring, autumn and winter. The dust samples were collected on glass filters using air aspirator and the organic matter of PM2.5 was extracted using Soxhlet extractor. The levels of polycyclic aromatic hydrocarbon compounds (PAH), nitro-PAH and dinitro-PAH were determined in the extract. Variable degree of air pollution with mutagenic substances was determined at the selected study site. A greater, negative effect of chemical compounds on DNA was determined in dust samples collected in the autumn-winter season in comparison to samples collected in the spring-summer season. In the majority of tests, higher mutagenicity was obtained in analyses conducted on total extracts in comparison to tests conducted in the presence of PAH pollutant fractions. The obtained mutagenic ratio values pointed to the presence of chemical compounds with a character of both promutagens and direct mutagens. Samples collected in the autumn-winter season were observed to have a higher diversity of organic substances absorbed on PM2.5 dusts. Particular samples differed in the total content and percent contribution of particular PAHs, nitro-PAHs, and other organic compounds. In addition, the identified substances included compounds belonging to different chemical classes: aliphatic compounds, cycloalkanes, mono- and bicycling arenes, polycyclic arenes, compounds containing oxygen, nitrogen, and sulphur.