Will the removal of carbon, nitrogen and mixed disinfectants occur simultaneously: The key role of heterotrophic nitrification-aerobic denitrification strain

Article

作者: Xie, Tian ; Zhang, Yi ; Gao, Jingfeng ; Guo, Yi ; Wang, Qian ; An, Jiawen

The capacity and mechanism of heterotrophic nitrification-aerobic denitrification (HNAD) strain (H1) to remove carbon, nitrogen, disinfectants chloroxylenol (PCMX) and benzethonium chloride (BEC) were investigated in this study. PCMX was removed via metabolism and chemical oxygen demand co-metabolism process. BEC was eliminated through bacterial adsorption, which greatly inhibited the removal of other pollutants. Carbon source optimization tests revealed that glucose was the optimal carbon source for co-removal of pollutants under mixed disinfectants circumstances (PCMX + BEC). Comparing the groups without (G1) and with disinfectants (G2), the content of extracellular polymeric substances was higher, and hydrophobicity was enhanced under the hazardous conditions of G2. All the nitrogen metabolism functional genes in G2 were up-regulated, and the electron transport system activity was also improved. At the same time, G2 had lower reactive oxygen species content, which reduced the probability of resistance genes dissemination, but the abundance of most quantified resistance genes was elevated in G2. Toxicity assessment assays found a dramatic reduction in the virulence of G2's effluent compared with the mixed disinfectants. The results confirmed that H1 strain could be used to treat the disinfectant-containing wastewater, which may aid in the application of HNAD process.

2024-12-01·Journal of Hazardous Materials

Evolution of microbial community and resistance genes in denitrification system under single and combined exposure to benzethonium chloride and methylparaben

Article

作者: Lu, Tianyi ; Wang, Yuxuan ; Gao, Jingfeng ; Xu, Hongxin ; Zhang, Ke ; An, Jiawen ; Zhang, Jinming

Benzethonium chloride (BZC) and methylparaben (MeP) are commonly added into cosmetics as preservatives, which are frequently detected in wastewater treatment plants. Different response patterns of denitrification system were proposed under single and combined exposure to BZC and MeP (0, 0.5, 5 mg/L) by evaluating system performance, functional genes, extracellular polymeric substance (EPS), cytotoxicity, microbial community structure and resistance genes (RGs). The inhibition effect of BZC on denitrification system was stronger than MeP, and the co-exposure of BZC and MeP showed synergistic effect, enhancing the inhibition effect of BZC single exposure. BZC and/or MeP could promote the diffusion of RGs in sludge, including intracellular RGs (si-RGs) and extracellular RGs (se-RGs). Moreover, the single exposure of BZC and co-exposure of BZC and MeP increased the dissemination risks of RGs in water (w-RGs). IntI1 and tnpA-04, mobile genetic elements (MGEs), correlated positively with diverse RGs from different fractions. Notably, the spread of RGs through horizontal gene transfer mediated by MGEs and the flow of si-RGs into extracellular and water were observed in this study.

2024-10-16·Cureus

Oral Bacteria Counter Using Dielectrophoretic Impedance Measurement: Usefulness and Usage Considerations

Article

作者: Umeda, Masahiro ; Kawashita, Yumiko ; Soutome, Sakiko ; Imakiire, Akira ; Nakamatsu, Moeko ; Nakamura, Yuichi

BACKGROUNDThe oral cavity hosts numerous bacteria that are associated with various systemic diseases. The Oral Bacteria Counter (PHC Corporation, Tokyo, Japan), a microorganism quantitative analyzer that utilizes dielectrophoretic impedance measurements, enables rapid bacterial counting and is widely used in dental practice in Japan. However, it may also detect nonviable bacteria. This study aimed to assess the impact of disinfectants, electrolytes, and viscosity on the accuracy of the Oral Bacteria Counter and to determine whether it measures non-viable bacteria similarly to viable bacteria.METHODSTo evaluate the effect of the disinfectants, samples of 7% povidone-iodine (PV-I), 0.2% benzethonium chloride, 5% chlorhexidine (CHX), 0.2% CHX, 0.05% CHX, sterile water, and saline were measured using the Oral Bacteria Counter. The effect of viscosity was assessed by mixing sterile water with glycerol in various ratios and measuring the dielectrophoretic impedance of the bacterial counts at different viscosities. For the electrolyte effects, samples of Staphylococcus aureus diluted in sterile water or saline were measured using the Oral Bacteria Counter. Additionally, samples of 7% PV-I or 5% CHX diluted in sterile water or saline were measured. Bacterial counts were then measured and compared using the Oral Bacteria Counter, our developed delayed real-time polymerase chain reaction (DR-PCR) method (which quantifies only viable bacteria), and culture methods.RESULTSDisinfectants such as 5% CHX and 7% PV-I produced high readings on the Oral Bacteria Counter, even when no viable bacteria were present. Higher glycerol concentrations, which increased the viscosity, resulted in lower bacterial counts. The presence of electrolytes, particularly saline, led to higher readings on the Oral Bacteria Counter, which detected both viable and non-viable bacteria, whereas DR-PCR and culture methods did not detect non-viable bacteria.CONCLUSIONThe Oral Bacteria Counter may be influenced by disinfectants, viscosity, and electrolytes, leading to potential inaccuracies in bacterial quantification. For accurate bacterial measurements, it is essential to consider these factors and ideally combine the results from the Oral Bacteria Counter with methods such as DR-PCR for more reliable assessment.

100 项与 Benzethonium Chloride 相关的药物交易

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