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Household water purifiers are increasingly used to treat drinking water at the household level, but their influence on the microbiological safety of drinking water has rarely been assessed. In this study, representative purifiers, based on different filtering processes, were analyzed for their impact on effluent water quality. The results showed that purifiers reduced chemical qualities such as turbidity and free chlorine. However, a high level of bacteria (102–106 CFU/g) was detected at each stage of filtration using a traditional culture-dependent method, whereas quantitative PCR with propidium monoazide (PMA) treatment showed 106–108 copies/L of total viable bacteria in effluent water, indicating elevated microbial contaminants after purifiers. In addition, high-throughput sequencing revealed a diverse microbial community in effluents and membranes. Proteobacteria (22.06–97.42%) was the dominant phylum found in all samples, except for purifier B, in which Melainabacteria was most abundant (65.79%). For waterborne pathogens, Escherichia coli (100–106 copies/g) and Pseudomonas aeruginosa (100–105 copies/g) were frequently detected by qPCR. Sequencing also demonstrated the presence of E. coli (0–6.26%), Mycobacterium mucogenicum (0.01–3.46%), and P. aeruginosa (0–0.16%) in purifiers. These finding suggest that water from commonly used household purifiers still impose microbial risks to human health. [ABSTRACT FROM AUTHOR]

Microbial contamination during fuel storage can cause fuel system fouling and corrosion. Characterizing microbial contamination is critical for preventing and solving these problems. In this study, culture-based combing with the culture-independent methods, were used to profile the microbial contamination in aviation fuel. High-throughput sequencing (HTS) modified by propidium monoazide (PMA) revealed a higher diversity of contaminating microorganisms in samples than the culture method. Proteobacteria (47%), Actinobacteria (21%) and Ascomycota (>99%, fungi) were the most abundant phyla, and the neglected archaea was also detected. Additionally, qPCR-based methods revealed all samples contained a heavy level of microbial contamination, which was more accurate than its culturable counterparts, and fungal contamination was still a problem in aviation fuel. The application of a PCR-based method gives deeper insight into microbial contamination in aviation fuel than the conventional culture method, thus using it for regular detection and accurate description of fuel contamination is strongly recommended in the case of explosive microbial growth. [ABSTRACT FROM AUTHOR]

Viable but non-culturable (VBNC) bacteria have attracted widespread attention since they are inherently undetected by traditional culture-dependent methods. Importantly, VBNC bacteria could resuscitate under favorable conditions leading to significant public health concerns. Although the total number of viable bacteria has been theorized to be far greater than those that can be cultured, there have been no reports quantifying VBNC pathogenic bacteria in full-scale drinking water treatment plants (DWTPs). In this work, we used both culture-dependent and quantitative PCR combination with propidium monoazide (PMA) dye approaches to characterize cellular viability. Further, we established a method to quantify viable pathogens by relating specific gene copies to viable cell numbers. Ratios of culturable bacteria to viable 16S rRNA gene copies in water and biological activated carbon (BAC) biofilms were 0–4.75% and 0.04–56.24%, respectively. The VBNC E. coli , E. faecalis , P. aeruginosa , Salmonella sp., and Shigella sp. were detected at levels of 0–103 cells/100 mL in source water, 0–102 cells/100 mL in chlorinated water, and 0–103 cells/g in BAC biofilms. In addition, differences between the total and viable community structures after ozonation and chlorination were investigated. The relative abundance of opportunistic pathogens such as Mycobacterium , Sphingomonas , etc. increased in final water, likely due to their chlorine resistance. In summary, we detected significant quantities of viable/VBNC opportunistic pathogens in full-scale DWTPs, confirming that traditional, culture-dependent methods are inadequate for detecting VBNC bacteria. These findings suggest a need to develop and implement rapid, accurate methods for the detection of VBNC pathogenic bacteria in DWTPs to ensure the safety of drinking water. ga1 • Distributions of VBNC pathogenic bacteria was quantified for the first time in full-scale DWTPs. • Residual amount of VBNC pathogenic bacteria were 0-102 cells/100 mL in chlorinated water. • Total and viable community structures were significantly different in some stages in DWTPs. • The relative abundance of potential pathogens increased after chlorination. [ABSTRACT FROM AUTHOR]