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The development of alternative techniques to efficiently inactivate bacterial suspensions is crucial to prevent transmission of waterborne illness, particularly when commonly used techniques such as heating, filtration, chlorination, or ultraviolet treatment are not practical or feasible. We examine the effect of MHz-order acoustic wave irradiation in the form of surface acoustic waves (SAWs) on Gram-positive (Escherichia coli) and Gram-negative (Brevibacillus borstelensis and Staphylococcus aureus) bacteria suspended in water droplets. A significant increase in the relative bacterial load reduction of colony-forming units (up to 74%) can be achieved by either increasing (1) the excitation power, or, (2) the acoustic treatment duration, which we attributed to the effect of the acoustic radiation force exerted on the bacteria. Consequently, by increasing the maximum pressure amplitude via a hybrid modulation scheme involving a combination of amplitude and pulse-width modulation, we observe that the bacterial inactivation efficiency can be further increased by approximately 14%. By combining this scalable acoustic-based bacterial inactivation platform with plasma-activated water, a 100% reduction in E. coli is observed in less than 10 mins, therefore demonstrating the potential of the synergistic effects of MHz-order acoustic irradiation and plasma-activated water as an efficient strategy for water decontamination., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Fecal samples collected for microbiome analyses are typically frozen to avoid postcollection changes in microbial composition. eNAT is a guanidine thiocyanate-based medium that stabilizes microbial DNA and allows safe specimen handling and shipping by inactivating microorganisms. We collected fecal samples (n = 50) from children undergoing hematopoietic stem cell transplantation. We divided samples into three aliquots: (a) stored in RNAlater and immediately transferred to -80°C; (b) stored in eNAT medium and immediately transferred to -80°C; and (c) stored in eNAT medium at ambient temperature (~20°C) for 30 days prior to transfer to -80°C. Mean (standard deviation) Shannon diversity and Chao1 indices in sample aliquots were 2.05 (0.62) and 23.8 (16.6), respectively. Comparing samples frozen immediately in RNAlater to samples frozen immediately in eNAT, there were no differences in Shannon diversity (p = .51), Chao1 richness (p = .66), and overall microbiome composition (p = .99). Comparing eNAT samples frozen immediately to samples stored at ambient temperature, we identified no differences in Shannon diversity (p = .65), Chao1 richness (p = .87), and overall microbiome composition (p = .99). Storage of fecal samples in eNAT at ambient temperature for 30 days did not alter microbiome richness, diversity, or composition. eNAT may be a useful medium for fecal microbiome studies, particularly when cold chain storage is unavailable., (© 2020 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.)

Bacterial sensing and inactivating is one of the key steps to prevent bacterial propagation and transfer. Here, using Ag nanoparticle-grafted tungsten oxide films (WO 3 /Ag), we developed a multifunctional platform that may act as a surface-enhanced Raman spectroscopy substrate for sensitively capturing and counting bacteria. Moreover, we demonstrated that the use of photon-triggered surface plasmon resonance of Ag on the WO 3 surface resulted in a significantly improved photocatalytic activity under visible light (638 nm). The photogenerated reactive oxygen species have been shown to be efficient in the inactivation of bacteria, and the bacteria inactivation process could be monitored in situ by Raman spectroscopy. On the basis of the obtained Raman results and fluorescence measurements of green fluorescence protein expressing bacteria, the active species triggered by hot spots was demonstrated to account for broken cell walls. The bacterial cell contents subsequently leaked out, leading to cell degradation. Potentially, our work may provide a promising strategy for capturing and monitoring the bactericidal process at low concentration and, specifically, may help in the investigation of related inactivation approaches and mechanisms.

In this study, the relationship between plasma gas temperature and the bactericidal effects on five of bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus (spore)) in liquid was investigated using a temperature-controllable plasma source. We determined that the bactericidal ability improved as the plasma gas temperature increased. Specifically, the bactericidal ability on E. coli of 80-℃ plasma was enhanced by as much as 6.3 times compared to that of 10-℃ plasma. The relationship between plasma gas temperature and the amount of hydroxyl radical, singlet oxygen, hydrogen peroxide, and ozone introduced into the solution was investigated. Our results also showed that each reactive species production increased by 2.1, 9.0, 1.6, and 17 times, respectively, with 80-℃ compared to 10-℃ plasma. The relationship between the bactericidal ability and amount of reactive species indicated that singlet oxygen and ozone introduced to the solution mostly influenced the bactericidal ability as the plasma gas temperature increased. We conclude that the plasma gas temperature is the crucial parameter for plasma sterilization.

PCR is effective in detecting bacterial DNA in samples, but it is unable to differentiate viable bacteria from inactivated cells or free DNA fragments. New PCR-based analytical strategies have been developed to address this limitation. Molecular viability testing (MVT) correlates bacterial viability with the ability to rapidly synthesize species-specific rRNA precursors (pre-rRNA) in response to brief nutritional stimulation. Previous studies demonstrated that MVT can assess bacterial inactivation by chlorine, serum, and low-temperature pasteurization. Here, we demonstrate that MVT can detect inactivation of Escherichia coli , Aeromonas hydrophila , and Enterococcus faecalis cells by UV irradiation. Some UV-inactivated E. coli cells transiently retained the ability to synthesize pre-rRNA postirradiation (generating false-positive MVT results), but this activity ceased within 1 h following UV exposure. Viable but transiently undetectable (by culture) E. coli cells were consistently detected by MVT. An alternative viability testing method, viability PCR (vPCR), correlates viability with cell envelope integrity. This method did not distinguish viable bacteria from UV-inactivated bacteria under some conditions, indicating that the inactivated cells retained intact cell envelopes. MVT holds promise as a means to rapidly assess microbial inactivation by UV treatment. IMPORTANCE UV irradiation is increasingly being used to disinfect water, food, and other materials for human use. Confirming the effectiveness of UV disinfection remains a challenging task. In particular, microbiological methods that rely on rapid detection of microbial DNA can yield misleading results, due to the detection of remnant DNA associated with dead microbial cells. This report describes a novel method that rapidly distinguishes living microbial cells from dead microbial cells after UV disinfection., (Copyright © 2017 American Society for Microbiology.)

Although, the High Hydrostatic Pressure (HHP) technology has been gaining gradual popularity in food industry since last two decades, intensive research is needed to explore the missing information. Bacterial inactivation in food by using HHP applications can be enhanced by getting deeper insights of the process. Some of these aspects have been already studied in detail (like pressure, time, and temperature, etc.), while some others still need to be investigated in more details (like pH, rates of compression, and decompression, etc.). Selection of process parameters is mainly dependent on type of matrix and target bacteria. This intensive review provides comprehensive information about the variety of aspects that can determine the bacterial inactivation potential of HHP process indicating the fields of future research on this subject including pH shifts of the pressure treated samples and critical limits of compression and decompression rates to accelerate the process efficacy.

Clinical solid waste (CSW) poses a challenge to health care facilities because of the presence of pathogenic microorganisms, leading to concerns in the effective sterilization of the CSW for safe handling and elimination of infectious disease transmission. In the present study, supercritical carbon dioxide (SC-CO2) was applied to inactivate gram-positive Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and gram-negative Escherichia coli in CSW. The effects of SC-CO2 sterilization parameters such as pressure, temperature, and time were investigated and optimized by response surface methodology (RSM). Results showed that the data were adequately fitted into the second-order polynomial model. The linear quadratic terms and interaction between pressure and temperature had significant effects on the inactivation of S. aureus, E. coli, E. faecalis, and B. subtilis in CSW. Optimum conditions for the complete inactivation of bacteria within the experimental range of the studied variables were 20 MPa, 60 °C, and 60 min. The SC-CO2-treated bacterial cells, observed under a scanning electron microscope, showed morphological changes, including cell breakage and dislodged cell walls, which could have caused the inactivation. This espouses the inference that SC-CO2 exerts strong inactivating effects on the bacteria present in CSW, and has the potential to be used in CSW management for the safe handling and recycling-reuse of CSW materials., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Antimicrobial photodynamic inactivation (aPDI) offers a promising alternative to combat drug-resistant bacteria. This study explores the potential of lapachol, a natural naphthoquinone derived from Tabebuia avellanedae, as a photosensitizer (PS) for aPDI. Lapachol's photosensitizing properties were evaluated using Staphylococcus aureus and Escherichia coli strains under blue LED light (450 nm). UV-vis spectroscopy confirmed lapachol's absorption peak at 482 nm, aligning with effective excitation wavelengths for phototherapy. Photoinactivation assays demonstrated significant bacterial growth inhibition, achieving complete eradication of S. aureus at 25 µg·mL−1 under light exposure. Scanning electron microscopy (SEM) revealed morphological damage in irradiated bacterial cells, confirming lapachol's bactericidal effect. This research underscores lapachol's potential as a novel photosensitizer in antimicrobial photodynamic therapy, addressing a critical need in combating antibiotic resistance. [ABSTRACT FROM AUTHOR]

Effective disinfection processes have been investigated to provide pathogen-free drinking water. Due to growing concern about the potential negative effects of cyanobacteria in portable water, their treatment has gained more attention recently. This study aims to compare the inhibition efficiencies of Gram-negative bacteria (Escherichia coli; E. coli), Gram-positive bacteria (Bacillus subtilis; B. subtilis), and cyanobacteria (Microcystis aeruginosa; M. aeruginosa) using UV-C and solar irradiation, and their combination process with H2O2. Over 6 log removal value (LRV) of E. coli and B. subtilis was achieved within 1 min of UV-C irradiation (0.76 ± 0.02 mW/cm2). The solar and solar/H2O2 (50 mg/L) processes effectively reduced (>99%) both bacteria after 20 min. E. coli was more sensitive to hydroxyl radicals (•OH) compared to the B. subtilis due to a different cell wall structure, resulting in a 0.18–0.62 higher LRV than B. subtilis. However, solar-based processes did not effectively inhibit M. aeruginosa (>52.23%). The UV-C/H2O2 (50 mg/L) process showed the highest inhibition rate for M. aeruginosa (77.83%) due to the generation of •OH, leading to oxidative damage to cells. Additionally, chlorophyll-a (Chl-a) was measured to indicate cell lysis of M. aeruginosa. The removal rate of Chl-a extracted by viable M. aeruginosa was higher using the UV-C process (93.03%) rather than the UV-C/H2O2 process (80.95%), because UV-C irradiation could be most effective in damaging Chl-a. [ABSTRACT FROM AUTHOR]

A facile carbon‐doping process is proposed to enhance the photocatalytic activity of anatase/rutile‐mixed phase TiO2 nanoparticles using polyethylene glycol (PEG). The TiO2‐PEG composite is loaded into a boat and covered tightly with Al foil to increase the pressure inside that boat during annealing. The boat is annealed for 1 h at different temperatures and PEG ratios. The annealing with 30% PEG at 300 °C enhances the decomposition of organic pollutants and bacterial inactivation under 405 nm light compared to the annealing without Al films. This annealing causes 2.5–3% carbon doping, introduces more oxygen vacancies, and converts PEG into organic compounds rich in CC bond components. These modifications of TiO2 can be attributed to carbon‐centered radicals produced from PEG during annealing. The modifications change the band structure to enhance the photogenerated carrier concentration responsible for the photocatalytic activity. The carbon doping narrows the anatase and rutile bandgaps, allowing the anatase phase to absorb 405 nm light. The introduced oxygen vacancies increase the electron‐trapping sites and raise the adsorbed oxygen groups enhancing the upward band bending and the depletion layer depth at the surface. The PEG‐converted compounds can transfer photogenerated electrons within the compounds to the TiO2 conduction band. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is an increasing challenge in semen preservation of breeding animals, especially in the porcine species. Bacteria are a natural component of semen, and their growth should be inhibited to protect sperm fertilizing capacity and the female's health. In pig breeding, where semen is routinely stored at 17°C in the liquid state, alternatives to conventional antibiotics are urgently needed. Photodynamic inactivation (PDI) of bacteria is a well-established tool in medicine and the food industry but this technology has not been widely adopted in semen preservation. The specific challenge in this setting is to selectively inactivate bacteria while maintaining sperm integrity and functionality. The aim of this study was to test the principle of PDI in liquid stored boar semen using the photosensitizer 5,10,15,20-tetrakis(N-methyl-4-pyridyl)-21H,23H-porphine (TMPyP) and a white light LED-setup. In the first step, photophysical experiments comprising singlet oxygen phosphorescence kinetics of TMPyP and determination of the photosensitizer triplet time revealed a sufficiently high production of reactive singlet oxygen in the Androstar Premium semen extender, whereas seminal plasma acted as strong quencher. In vitro experiments with extended boar semen showed that the established PDI protocol preserves sperm motility, membrane integrity, DNA integrity, and mitochondrial activity while efficiently reducing the bacteria below the detection limit. A proof-of-concept insemination study confirmed the in vivo fertility of semen after photodynamic treatment. In conclusion, using the PDI approach, an innovative tool was established that efficiently controls bacteria growth in extended boar and maintains sperm fertility. This could be a promising contribution to the One Health concept with the potential to reduce antimicrobial resistance in animal husbandry. [ABSTRACT FROM AUTHOR]

The improvement of photodynamic inactivation (PDI) significantly depends on the development of new families of photosensitizers (PSs). In this sense, three BOPHY derivatives (BP, BP‐Br and BP‐I) were synthetized, studied, and compared to assess their antimicrobial photodynamic properties. BP is an interesting fluorescent probe for cell imaging, while the halogenated analogs (BP‐Br and BP‐I) are excellent oxygen photosensitizing agents. BP compound presented a fluorescence quantum yield close unity and showed no reactive oxygen species (ROS) production. In contrast, BP‐I did not show emission properties but exhibited a high production of ROS through both photodynamic mechanisms, generating singlet oxygen (type II) and superoxide radical anion (type I) under aerobic light irradiation. BP‐Br presented an adequate balance between ROS production and emission properties. The photokilling action and the binding to bacterial cells of these macrocycles were evaluated in vitro against methicillin‐resistant Staphylococcus aureus (MRSA) and Escherichia coli bacteria. Our results demonstrated that the halogenated BOPHY derivatives were effective PSs in inactivating MRSA using shorter irradiation periods. In addition, the antimicrobial action sensitized by these BOPHYs was potentiated by adding KI. The combination of halogenated BOPHY and KI led to a complete elimination of both Gram‐positive and Gram‐negative bacteria. Hence, BP‐Br and BP‐I prove to be potent broad‐spectrum antimicrobial PSs. To the best of our knowledge, this is the first time that BOPHY derivatives have been applied to photokill pathogenic microorganisms. [ABSTRACT FROM AUTHOR]

The underlying mechanisms and biochemical actions responsible for inactivation of pathogenic gram-positive Staphylococcus aureus (S. aureus) and gram-negative Salmonella abony (S. abony) bacteria upon exposure to sub-atmospheric plasma has been investigated. Reduction in colony forming units of the bacteria is established in 60 min and 40 min for S. aureus and S. abony respectively via 6-log reduction curves. The percentage change in reactive oxygen species, such as •OH and H2O2 formed on bacterial membrane during plasma exposure are analysed using spectroflurometer. S. aureus exhibited a significant increase of 324.23% and 1554.84% in •OH and H2O2 radicals respectively. Whereas, 98.14% and 54.49% increase in •OH and H2O2 radicals respectively was observed in S. abony. The oxidation and degradation of DNA is analysed using an ultra violet visible spectrophotometer. The leakage of proteins, lipids, and nucleic acid molecules due to plasma exposure is studied by Attenuated Total Reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). The alteration of secondary protein structure on the cell membrane is observed using Circular Dichroism. Upon exposure to plasma, S. aureus shows a secondary protein structural transition from α-helix (2.4%), β-sheet (78.3%) mixture to modified β-sheet structure (0% α-helix, 79.1% β-sheet). Whereas, S.abony shows a transition from α-helix (1%), β-sheet (64.9%) mixture to modified β-sheet structure (0% α-helix, 74.5% β-sheet). The bacterial morphological study (swelling/shrinking) done using Field Emission Scanning Electron Microscopy (FE-SEM) reveals the deformation of cell membrane. Above findings pave the way for a better understanding of the processes of antimicrobial inactivation strategies when the plasma sterilization process is employed. [ABSTRACT FROM AUTHOR]

Studies have demonstrated bacterial inactivation by radiations at wavelengths between 400 and 500 nm emitted by low-power light sources. The phototoxic activity of these radiations could occur by oxidative damage in DNA and membrane proteins/lipids. However, some cellular mechanisms can reverse these damages in DNA, allowing the maintenance of genetic stability. Photoreactivation is among such mechanisms able to repair DNA damages induced by ultraviolet radiation, ranging from ultraviolet A to blue radiations. In this review, studies on the effects of violet and blue lights emitted by low-power LEDs on bacteria were accessed by PubMed, and discussed the repair of ultraviolet-induced DNA damage by photoreactivation mechanisms. Data from such studies suggested bacterial inactivation after exposure to violet (405 nm) and blue (425–460 nm) radiations emitted from LEDs. However, other studies showed bacterial photoreactivation induced by radiations at 348–440 nm. This process occurs by photolyase enzymes, which absorb photons at wavelengths and repair DNA damage. Although authors have reported bacterial inactivation after exposure to violet and blue radiations emitted from LEDs, pre-exposure to such radiations at low fluences could activate the photolyases, increasing resistance to DNA damage induced by ultraviolet radiation. [ABSTRACT FROM AUTHOR]

Ozone based disinfection is one of the approved green technologies for preservation of meat and meat products. The study had discussed about the isolation and characterization of meat borne bacteria using 16 S rRNA PCR and the effect of aqueous ozone on those microbes in-vitro. The important bacteria such as Staphylococcus sp., Bacillus sp., E.coli, Enterobacter sp., Proteus sp., Providencia sp., Pseudomonas sp., were isolated from meat, meat products and processing environment and were identified up to genus level using 16 S rRNA gene sequencing. Individual bacterial strains (108 cfu/ml) dissolved in a sterile diluent were subjected to aqueous ozone (O3, 0.1 mg/kg) for 0, 0.5, 1, 2, 4, 8 and 15 min. Inactivation kinetics data was fitted into GInaFiT software. Ozone treatment for 15 min resulted in a reduction of 4.9, 5.1, 4.5 and 5.8 log10 concentration of Proteus sp. and Providencia sp., Enterococcus spp., Citrobacter sp., and Staphylococcus sp., respectively. Biphasic shoulder, double Weibull and Weibull + tail models were good fit for inactivation data. Analysis of 4-D values indicated that Staphylococcus sp., was more susceptible to ozone (4-D = 7.5 min) and Citrobacter sp. was the least susceptible to ozone (4-D = 13.8 min). [ABSTRACT FROM AUTHOR]

In the context of climate change, freshwater shrinkage and industrialization, human diseases are increasing due to water pollution by toxic chemicals and pathogenic bacteria, calling for advanced methods to treat contaminated water. Here we review piezocatalysis, an overlooked method to degrade organic pollutants and inhibit bacteria. Recent research shows that the properties of piezoelectric materials have remarkably progressed due to a high surface area and a built-in electric field at the nanolevel. This induces an efficient charge carrier generation, which allows fast reaction mediated by reactive oxygen species. We discuss bacterial growth, methods for water treatment and the piezocatalytic mechanism with focus on charge generation, cavitation and bacterial inactivation by reactive oxygen species. We present applications to the removal of dyes and pathogenic bacteria. [ABSTRACT FROM AUTHOR]

We report the successful inactivation of P. aeruginosa strain by femtosecond infrared (IR) laser radiation at the resonant wavelengths of 3.15 μm and 6.04 μm, chosen due to the presence of characteristic molecular vibrations in the main structural elements of the bacterial cells in these spectral ranges: vibrations of amide groups in proteins (1500–1700 cm−1), and C-H vibrations in membrane proteins and lipids (2800–3000 cm−1). The underlying bactericidal structural molecular changes were revealed by the stationary Fourier-transform IR spectroscopy, with the spectral peaks parameters being obtained by Lorentzian fitting with the hidden peaks revealed by the second derivative calculations, while no visible damage to the cell membranes was identified by scanning and transmission electron microscopy. [ABSTRACT FROM AUTHOR]

The development of a convenient, sensitive, rapid and self-sterilizing biosensor for microbial detection is important for the prevention and control of foodborne diseases. Herein, we designed a surface-enhanced Raman scattering (SERS) sensing nanoplatform based on a capture–enrichment–enhancement strategy to detect bacteria. The gold−Azo@silver−cetyltrimethylammonium bromide (Au−Azo@Ag−CTAB) SERS nanotags were obtained by optimizing the synthesis process conditions. The results showed that the modification of CTAB enabled the nanotags to bind to different bacteria electrostatically. This SERS sensing nanoplatform was demonstrated to be fast (15 min), accurate and sensitive (limit of detection (LOD): 300 and 400 CFU/mL for E. coli and S. aureus, respectively). Of note, the excellent endogenous antibacterial activity of CTAB allowed the complete inactivation of bacteria after the assay process, thus effectively avoiding secondary contamination. [ABSTRACT FROM AUTHOR]

Bacterial biofilms are difficult to treat due to their resistance to traditional antibiotics. Although photodynamic therapy (PDT) has made significant progress in biomedical applications, most photosensitizers have poor water solubility and can thus aggregate in hydrophilic environments, leading to the quenching of photosensitizing activity in PDT. Herein, a benzoselenadiazole-containing ligand was designed and synthesized to construct the zirconium (IV)-based benzoselenadiazole-doped metal-organic framework (Se-MOF). Characterizations revealed that Se-MOF is a type of UiO-68 topological framework with regular crystallinity and high porosity. Compared to the MOF without benzoselenadiazole, Se-MOF exhibited a higher 1O2 generation efficacy and could effectively kill Staphylococcus aureus bacteria under visible-light irradiation. Importantly, in vitro biofilm experiments confirmed that Se-MOF could efficiently inhibit the formation of bacteria biofilms upon visible-light exposure. This study provides a promising strategy for developing MOF-based PDT agents, facilitating their transformation into clinical photodynamic antibacterial applications. [ABSTRACT FROM AUTHOR]

The combination of photodynamic therapy with antibiotics or antimicrobial peptides for inactivation of bacteria is an area of growing interest due to the synergistic effect already observed by many authors. It has been shown that the efficiency of this dual antimicrobial therapy is highly dependent on the structure of the photosensitizer, being tetrapyrrolic macrocycles the ones with most promising results. There are a few review articles in the recent literature describing the main microbiological results concerning this dual inactivation of bacteria, but none of them focus on the synthetic processes of these photosensitizers and their remarkable chemical versatility. Therefore, herein we present an overview on synthetic methodologies for preparation of tetrapyrrolic macrocycles and their conjugates with antibiotics or antimicrobial peptides, for use in dual inactivation of bacteria. This review will be divided in two sections concerning the physical or covalent combinations of PS with antibiotic/cationic peptides, followed by brief critical analysis on their corresponding antimicrobial outcomes. [ABSTRACT FROM AUTHOR]

A novel S-scheme CuBi 2 O 4 /Bi 4 O 5 I 2 heterojunction was synthesized by hydrothermal and following calcination route. The photocatalytic performance was estimated by removing four different pollutants (TC, BPA, RhB, and MO) and two kinds of bacteria (E. coli and S. aureus) under LED light. The optimum sample 37% CuBi 2 O 4 /Bi 4 O 5 I 2 can degrade 81% tetracycline (TC) within 90 min, and can inactivate 100% E. coli in 20 min and S. aureus in 40 min. h+, •OH and •O 2 − are active species in the photocatalytic process. The synergistic effect of S-scheme heterojunction makes it possess excellent photocatalytic activity. [Display omitted] The CuBi 2 O 4 /Bi 4 O 5 I 2 S-scheme heterojunction structure was constructed by a hydrothermal and subsequent calcination route. The combination of CuBi 2 O 4 and Bi 4 O 5 I 2 produced excellent photocatalytic performance under an LED light. A series of technical characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), were used to determine the successful construction of S-scheme CuBi 2 O 4 /Bi 4 O 5 I 2 composites. The improvement of photogenerated carrier separation efficiency helped to achieve the best photocatalytic performance of 37% CuBi 2 O 4 /Bi 4 O 5 I 2 , which can degrade tetracycline (TC) to 81.67% in 90 min, and completely inactivate Escherichia coli (E. coli) in 20 min and Staphylococcus aureus (S. aureus) in 40 min. The effects of some key parameters (such as the concentration of pollutants, the amount of catalyst, pH value of a solution, various inorganic anions and various water substrates) and the possible degradation path of tetracycline were systematically studied. Finally, the removal of pollutants and inactivation of bacterial mechanisms based on the S-scheme heterojunction (CuBi 2 O 4 /Bi 4 O 5 I 2) was proposed. This study provides insight into the synthesis of S-scheme heterojunction photocatalysts, which can efficiently degrade organic pollutants and inactivate bacteria under LED light irradiation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Advanced oxidation processes (AOPs), specifically photocatalysis have gained an essential attraction in the field of micro pollutants degradation. Synthesis and use of proper photocatalysts for target pollutant and water matrix scenarios constitute the primary field of research. In this study, hydrothermal and sol‐gel synthesis methods were applied for the synthesis of nanocomposites in the form of spinel ferrite CuFe2O4 (CF) nanocomposites and CuFe2O4‐Ti (CFT) and CuFe2O4‐Ti‐GO (CFT‐GO) heterojunction nanocomposites with magnetic properties. And prior to photocatalytic activity based screening, bacteria inactivation and antibiotic degradation potentials of optimum NCs were determined under visible light conditions. PEG and Cydonia oblonga seed extract were used as chemical and bio‐chemical reducing‐stabilizing agents throughout the hydrothermal synthesis step. The as produced NCs were characterized by XRD, SEM, EDX, BET Surface, FTIR, RAMAN, Photoluminescence and Diffuse Reflectance Spectroscopy analysis. RESULTS: According to the pre‐screening findings based on the methylene blue removal efficiencies of NCs under UV‐vis, CFT %1(w/w) have provided >70% removal at the end of 120 min. While CFT‐GO NCs yielded 30% removal rates (Pseudo first order kinetic constants of 0.012 and 0.0036 min−1 respectively). The reactive oxygen species formation by CFT‐GO NC photocatalysts was hindered as a result of conjugation mechanism between MB and aromatic regions of GO and due to high adsorption capacity of the NC. Based on photocatalytic bacteria inactivation findings of the pre‐screened NCs; >99% of bacteria were inactivated following 90 min of photocatalytic oxidation by CFT‐GO 3%. According to the Modified HOM model, k2 values were estimated to be 1.36 and 1.93 for CFT 1% and CFT‐GO 3% NCs, while no initial and post delay of bacteria inactivation was observed for the latter. Optimum photocatalyst dose was examined (to be 0.6 g L−1) based on photocatalytic degradation of sulfamethoxazole antibiotic at varying initial concentration ([C]0 SMX = 10 and 2.5 mg L−1). The CFT 1% photocatalysts have provided >89 % SMX degradation level (for [C]0 SMX = 2.5 g L−1). For the case of mixture of antibiotics [C]0 total = 2.5 g L−1, CFT 1% have provided >99.5%, >90%, >90% and 28% photocatalytic degradation levels at the end of 180 min for SMX AMP, TET and CLRT antibiotics respectively, while the total rate of degradation was 77%. CONCLUSION: By using the green synthesis procedure, copper ferrite nanocomposites (CF) was successfully fabricated with comparable physical and chemical properties. This study not only reports on the green synthesis of common p‐type spinel CuFe2O4 but also offer new design of photocatalysts capable of providing efficient removal of antibiotics and bacteria inactivation under visible‐light irradiation. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Sensitive detection and effective inactivation of bacteria are essential in preventing foodborne bacterial infection that poses a significant threat to human health. Herein, a near-infrared (NIR)-driven multifunctional photoelectrochemical (PEC) biosensor was constructed for detection and inactivation of S. aureus. Based on the covalent bonding between amine and carboxyl groups, carboxyl-functionalized SA31 aptamer was immobilized on the PDA/MnO 2 photoelectrode. In the presence of S. aureus , SA31 aptamer can specifically capture S. aureus , causing the decrease of photocurrent signal owing to steric hindrance effect. Leveraging photocurrent-off signal, there existed a satisfied linear relationship between the photocurrent variation and the logarithm of S. aureus concentration, achieving a wide linear range from 10 to 107 CFU/mL with a low detection limit of 2.0 CFU/mL. Notably, PDA/MnO 2 with peroxidase-like activity facilitated the catalytic oxidation of S. aureus with assistance of hydrogen peroxide (H 2 O 2) to cause the inactivation of S. aureus. Desorption of inactivated S. aureus from the photoelectrode led to a recovery of photocurrent signal, enabling a "signal on" switch. Simultaneously, the excellent photothermal performance of the PDA/MnO 2 converted light energy into heat energy under the irradiation of NIR light (808 nm, 1.5 W/cm2), triggering the synergistic antibacterial effect against S. aureus (97.36%). This work provides a novel strategy for fabricating the detection and inactivation of bacteria in practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bismuth oxides were synthetized by grinding, coprecipitation and hydrothermal. • Bismuth oxides were tested for air, water purification, and bacteria inactivation. • BiOI/Bi 4 I 2 O 5 , BiOI 0.5 Cl 0.5 and BiOI 0.5 Br 0.5 exhibit the highest photoactivity. • Higher antibacteria activity of BiOX 0.5 I 0.5 (X:Cl, Br) than TiO 2 P25 under UV light. • Light absorption, band energy and charge recombination control their reactivity. Fifteen bismuth oxyhalides were synthetized, including BiOX, BiOX/Bi x O y X z , heterostructures and BiOX x Y 1− x (X, Y = Cl, Br, I) solid solutions. The photocatalytic activity and intermediates formation of as-prepared bismuth-based semiconductors (BBS) were compared with the benchmark TiO 2 P25 photocatalyst for NOx air purification, phenol decomposition, and E.Coli bacteria inactivation. TiO 2 P25 possessed the highest photocatalytic oxidation rate of phenol (K = 0.003 min−1) and NO degradation efficiency (η = 38 %) when exposed to UV light, but also the lowest performance under visible light on both photocatalytic process (K = 0.0007 min−1 and η = 14 %). Under visible light, BiOI/Bi 4 O 5 I 2 or solid solutions (BiOI 0.5 Cl 0.5 and BiOI 0.5 Br 0.5) enhanced the photocatalyic for phenol degradation (K = 0.01–0.026 min−1) and NO (35–37 %). BBS samples generated more NO 2 during NOx oxidation, but less typical intermediates (benzoquinone, hydroquinone and catechol) during phenol decomposition were detected. BiOCl 0.5 I 0.5 and BiOBr 0.5 I 0.5 composites exhibited the most outstanding antibacterial performance under both irradiation conditions resulting in E. coli 102-3 cfu/mL after 60 min irradiation. The differences can be mainly linked to a different ROS-mediated mechanism of TiO 2 and BBS. The BBS photocatalytic results is closely related to the balance between effective light absorption and adequate redox potentials. [ABSTRACT FROM AUTHOR]

Phthalocyanine derivatives have been proposed as photosensitizers for the treatment of several microbial infections. In this review, the progress in the structures of phthalocyanines was analyzed, considering that these compounds can easily functionalize and can form complexes with various metal ions. In this sense, different substituents were used to increase the interaction with the microorganisms, improving their photodynamic inactivation. Furthermore, these photosensitizers absorb strongly at phototherapeutic window, emit red fluorescence, and efficiently produce the formation of reactive oxygen species. Subsequently, the influence of binding, bacteria types, cell density, washing effect, and media on photoinactivation was remarked to elimination of microbes. Finally, photokilling of bacterial biofilm by phthalocyanines and the mechanism of action were discussed. Therefore, this review brings together the main features of phthalocyanines as antimicrobial phototherapeutic agents. [ABSTRACT FROM AUTHOR]

UV light is a tool associated with the denaturation of cellular components, DNA damage, and cell disruption. UV treatment is widely used in the decontamination process; however, predicting a sufficient UV dose by using traditional methods is doubtful. In this study, an in-house UVC apparatus was designed to investigate the process of the inactivation of five indicator bacteria when the initial cell concentrations and irradiation intensities varied. Both linear and nonlinear mathematical models were applied to predict the inactivation kinetics. In comparison with the Weibull and modified Chick-Watson models, the Chick-Watson model provided a good fit of the experimental data for five bacteria, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus faecalis, and Bacillus subtilis. The specific death rate (kd) significantly increased when the irradiation intensity (I) increased from 1.41 W/m² to 3.02 W/m² and 4.83 W/m² (P, 0.05). Statistical analysis revealed no significant difference in the kd values among the groups of tested Grampositive bacteria, Gram-negative bacteria, and B. subtilis spores, but the kd values differed among groups (P, 0.05). The death rate coefficient (k) varied from species to species. The k values of the tested Gram-positive bacteria were higher than those of the Gram-negative bacteria. The thick peptidoglycan layer in the Gram-positive membrane was responsible for UVC resistance. The high guanine-cytosine (GC) content in bacteria also contributed to UV resistance due to the less photoreactive sites on the nucleotides. This investigation provides a good understanding of bacterial inactivation induced by UVC treatment. [ABSTRACT FROM AUTHOR]

The molecular mechanism underlying modulation of metamorphosis of the bivalve Mytilus coruscus by bacteria remains unclear. Here, the functional role of the thioesterase gene tesA of the bacterium Pseudoalteromonas marina in larval metamorphosis was examined. The aim was to determine whether inactivation of the tesA gene altered the biofilm-inducing capacity, bacterial cell motility, biopolymers, or the intracellular c-di-GMP levels. Complete inactivation of tesA increased the c-di-GMP content in P. marina, accompanied by a reduced fatty acid content, weaker motility, upregulation of bacterial aggregation, and biofilm formation. The metamorphosis rate of mussel larvae on ΔtesA biofilms was reduced by ∼ 80% compared with those settling on wild-type P. marina. Exogenous addition of a mixture of extracted fatty acids from P. marina into the ΔtesA biofilms promoted the biofilm-inducing capacity. This study suggests that the bacterial thioesterase gene tesA altered the fatty acid composition of ΔtesA P. marina biofilms (BF) through regulation of its c-di-GMP, subsequently impacting mussel metamorphosis. [ABSTRACT FROM AUTHOR]

• Superior E. coli disinfection efficacy occurred by unactivated PMS vs. PDS/H 2 O 2. • Kinetic, biochemical, and genetic analyses defined the inactivation path. • SO 4 •− was the pivotal ROS, generated by the reaction between PMS & biomolecules. • External oxidation leads to cell envelope disruption and intracellular attacks. • Mutants' tests uncovered gene responses induced by intracellular radical pathways. This study examined the antimicrobial efficacy of peroxymonosulfate (PMS) against bacteria, using Escherichia coli (E. coli) as a model organism. Our investigation delineates the complex mechanisms exerted by unactivated PMS. Thus, an initial redox reaction between PMS and the target biomolecules of bacteria generates SO 4 •− as the pivotal reactive species for bacterial inactivation; to a lesser extent, •OH, 1O 2 , or O 2 •− may also participate. Damage generated during oxidation was identified using an array of biochemical techniques. Specifically, redox processes are promoted by PMS and SO 4 •− targets and disrupt various components of bacterial cells, predominantly causing extracellular damage as well as intracellular lesions. Among these, external events are the key to cell death. Finally, by employing gene knockout mutants, we uncovered the role of specific gene responses in the intracellular damage induced by radical pathways. The findings of this study not only expand the understanding of PMS-mediated bacterial inactivation but also explain the ten-fold higher effectiveness of PMS than that reported for H 2 O 2. Hence, we provide clear evidence that unactivated PMS solutions generate SO 4 •− in the presence of bacteria, and consequently, should be considered an effective disinfection method. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a background-free surface-enhanced Raman scattering (SERS) chip with a sandwich configuration was fabricated to enable reliable detection and photothermal inactivation of multiple bacteria. The SERS chip consists of a graphene-coated, phenylboronic-modified plasmonic gold substrate (pAu/G/PBA), and two aptamer-functionalized core (gold)-shell (Prussian blue/Poly-L-lysine and 4-mercaptobenzonitrile/polydopamine) SERS tags (Au@PB@PLL@Apt and Au@MB@PDA@Apt). The detection signals rely on the characteristic and nonoverlapping Raman bands of the SERS tags within the Raman-silent region (1800-2800 cm−1), where no background signals from the sample matrix are observed, leading to improved detection sensitivity and accuracy. Considering the relatively large size of bacteria (e.g., micron level), a rapid Raman mapping technique was chosen over conventional point-scan methods to achieve more reliable quantitative analysis of bacteria. This technique involves collecting and analyzing intensity signals of SERS tags from all the scattering points with an average ensemble effect, which is facilitated by the use of Python. As a proof-of-concept, model bacterium of Salmonella typhimurium and Staphylococcus aureus were successfully detected using the SERS chip with a dynamic range of 10–107 CFU/mL. Additionally, the SERS chip demonstrated successful detection of these bacteria in whole blood samples. Moreover, the photothermal effect of pAu/G led to efficient bacteria elimination, achieving approximately 100% eradication. This study integrated a background-free SERS chip with a Python-assisted rapid Raman mapping technique, resulting in a reliable, rapid and accurate method for detecting and eliminating multiple bacteria, which may provide a promising alternative for multiple screening of bacteria in real samples. [ABSTRACT FROM AUTHOR]

Physical and chemical cleaning for the removal of indoor microorganisms, which can cause allergic reactions and respiratory diseases, is labor-intensive and time-consuming. An ultra-low volume (ULV) sprayer, a newly introduced device to inactivate pathogenic microorganisms, allows the disinfectant particles to reach hard-to-reach spaces indoors and is more cost-effective than the existing methods. However, few studies have been conducted to verify the efficiency of the ULV sprayer. Here, we verified the disinfection efficiency of the ULV sprayer for inactivating total bacteria present on indoor surfaces, considering the factors affecting bacteria inactivation, and presented the optimal ULV sprayer usage conditions to achieve the highest disinfection efficiency depending on room size. The total bacteria removal efficiency was high (range: 0.56–2.46 log10 reductions), including hard-to-reach spaces. A response surface model was developed to identify the individual and interactive effects of the disinfectant concentration, spray amount, and room size on total bacteria disinfection efficiency. These three variables had interactive effects on the total bacteria disinfection efficiency. The experimental data were fitted to a second-order polynomial model, with high coefficients of determination (R2) for all models (R2 > 0.82). The optimum conditions were a spray amount of 3.08–6.40 L in 160 m3, 3.78–7.22 L in 230 m3, and 5.68–8 L in 300 m3 surface area when using dilution rates of 100 times. These conditions predicted a bacterial disinfection efficiency of >1.10 log10 reductions (92%) on all surfaces. Our results clearly indicate that the ULV sprayer effectively inactivates total bacteria present on indoor surfaces. [ABSTRACT FROM AUTHOR]

Graphene oxide/PtNPs/Fe2O3"dual‐propelled" catalytic and fuel‐free rotary actuated magnetic Janus micromotors modified with the lanbiotic Nisin are used for highly selective capture/inactivation of gram‐positive bacteria units and biofilms. Specific interaction of Nisin with the Lipid II unit of Staphylococcus Aureus bacteria in connection with the enhanced micromotor movement and generated fluid flow result in a 2‐fold increase of the capture/killing ability (both in bubble and magnetic propulsion modes) as compared with free peptide and static counterparts. The high stability of Nisin along with the high towing force of the micromotors allow for efficient operation in untreated raw media (tap water, juice and serum) and even in blood and in flowing blood in magnetic mode. The high selectivity of the approach is illustrated by the dramatically lower interaction with gram‐negative bacteria (Escherichia Coli). The double‐propulsion (catalytic or fuel‐free magnetic) mode of the micromotors and the high biocompatibility holds considerable promise to design micromotors with tailored lanbiotics that can response to the changes that make the bacteria resistant in a myriad of clinical, environmental remediation or food safety applications. [ABSTRACT FROM AUTHOR]

• Photo-Fenton at neutral pH leads to simultaneous disinfection and CEC removal. • Apparent kinetic constants linearly increase when decreasing liquid depth. • The cost ranges from 0.13 to 0.49 €/m3 regarding treatment goal. • Operating cost with Fe3+-EDDS is around 50–75 % higher than with FeSO 4. • Photo-Fenton with Fe3+-EDDS removes 80 % CECs, while only 35 % is removed with FeSO 4. For the first time, two strategies of solar photo-Fenton at neutral pH (with FeSO 4 and Fe3+-EDDS) are techno-economically assessed. With the target of simultaneous wastewater disinfection and removal of contaminants of emerging concern (CECs), a cost estimation ranging from 0.13 to 0.49 €/m3 as a function of the treatment goal is presented. To this end, the effects of liquid depth (5, 10 and 15 cm) and the iron species were studied at lab-scale. Afterwards, the feasibility of both operating strategies was evaluated and validated outdoors at pilot plant scale in low-cost raceway pond reactors. For the joint-removal of bacteria and CECs, the use of FeSO 4 as iron source was cheaper than Fe3+-EDDS. However, it is important to highlight that although bacterial inactivation reached > 3 log, only around 35 % of CEC degradation was achieved with FeSO 4 , while more than 80 % CEC load was removed with Fe3+-EDDS. [ABSTRACT FROM AUTHOR]

Inactivation of microorganism (bacteria, fungi, alga and plankton) using ultrasonic waves has attracted significant attention. However, the details of the inactivation mechanisms have not been cleared. This study aims to clarify the inactivation mechanisms of bacteria and fungi by acoustic cavitation. Escherichia coli (E. coli), Saccharomyces cerevisiae (S. cerevisiae) and Bacillus subtilis (B. subtilis) were used as the test microorganism. Inactivation was attempted by ultrasonic irradiation at frequencies of 20 kHz to 4.4 MHz and an acoustic power power of 10 W. Different frequency dependences of the inactivation were confirmed in E. coli, S. cerevisiae and B. subtilis. Based on these data, the mechanism of inactivation of microorganism is discussed with a focus on cell characteristics. [ABSTRACT FROM AUTHOR]

This work investigated the properties of Paracoccus yeei VKM B-3302 bacteria isolated from activated sludge and immobilized in an N-vinylpyrrolidone-modified poly(vinyl alcohol) matrix. The developed hydrogel formed a network structure to enable the entrapment of microbial cells with their viability and biocatalytic properties preserved, which ensured the technological possibility of replicating expendable biosensor receptor elements. A new ratio of the components for the synthesis selected in this work enabled producing a copolymer of an earlier undescribed chemical structure, which can be efficiently used for immobilization of highly sensitive P. yeei bacteria. A biological oxygen demand (BOD) biosensor with these bacteria and matrix was shown to possess a long-time stability exceeding that described earlier, to have a broad substrate specificity and to exceed approximately tenfold the nearest analogues by its sensitivity and the lower boundary value of 0.05 mg/dm3. The biosensor enabled assays of water samples initially attributed to pure samples (the BOD range, 0.05–5.0 mg/dm3). BOD assays of water samples from various sources showed the use of the receptor element of this composition to enable the data that closely correlated with the standard method (R2 = 0.9990). [ABSTRACT FROM AUTHOR]

Background: This study is to elucidate the disinfection effect of ozone producing low-pressure Hg vapor lamps against human pathogens. Ozone producing low-pressure Hg vapor lamps emit mainly 254 nm ultraviolet light C (UVC) with about 10% power of Vacuum-ultraviolet (VUV) light at 185 nm. The combination of UVC and VUV can inactivate airborne pathogens by disrupting the genetic materials or generation of reactive oxygen species, respectively. In this study, inactivation of common bacteria including Escherichia coli ATCC25922 (E. coli), Extended Spectrum Beta-Lactamase-producing E. coli (ESBL), Methicillin-resistant Staphylococcus aureus (MRSA) and Mycobacterium tuberculosis (MTB), and that of influenza A viruses H1N1 and H3N2 under the radiation from ozone producing low-pressure Hg vapor lamps was examined. Log reduction values at different treatment durations were determined.Methods: In vitro tests were carried out. Various bacterium and virus suspensions were added onto nitrocellulose filter papers and subjected to the illumination from ozone producing low-pressure Hg vapor lamps. The extents of pathogen inactivation at different illumination times were investigated by conducting a series of experiments with increasing duration of illumination. log10 reduction in CFU/ml and reduction at log10(TCID50) were respectively measured for bacteria and viruses. The disinfection effectiveness of this type of lamps against the pathogens under the environment with a moderate barrier to light was therefore evaluated.Results: Ozone producing low-pressure Hg vapor lamp successfully inactivated these human pathogens. Nevertheless, among these pathogens, disinfection of MTB required more intense treatment. In the best tested situation, 3-log10 inactivation of pathogens can be achieved with ≤10 min of VUV treatment except MTB which needed about 20 min. This demonstrated the high resistance against UV disinfection of MTB.Conclusions: Following the criteria that valid germicidal results can be reflected with 3-log10 inactivation for bacteria, 4-log10 inactivation for viruses and 5-log10 inactivation for MTB, most of the bacteria required ≤10 min of VUV treatment, 20 min for the influenza viruses while MTB needed about 30 min VUV treatment. This indicated that VUV light is an effective approach against different environmental microorganisms. [ABSTRACT FROM AUTHOR]

Bacterial inactivation is a crucial aspect of sanitation and hygiene. The effectiveness of slightly acidic electrolyzed water (SAEW) for reduction or removal of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis was evaluated. The bactericidal activity of SAEW and sodium hypochlorite (NaOCl) against E. coli and P. aeruginosa were compared through in vitro experiments. The effectiveness of SAEW spray was tested against S. epidermidis. Results showed that SAEW had a more powerful bactericidal activity than NaOCl at the same available chlorine concentrations. For E. coli, SAEW decreased the bacterial counts from 8.4 log10 CFU/mL to less than 3.9 log10 CFU/mL; NaOCl with the same available chlorine of 0.5 mg/L, caused a decrease from 8.4 log10 CFU/mL to 7.1 log10 CFU/mL. For P. aeruginosa, SAEW caused bacterial counts to decrease from 8.5 log10 CFU/mL to less than 4.1 log10 CFU/mL against 8.5 log10 CFU/mL to 6.2 log10 CFU/mL for NaOCl with the same available chlorine of 0.5 mg/L. Spray experiments showed that 10 mg/L of SAEW spray decreased the bacterial counts of S. epidermidis from 3.7 log10 CFU/m3 to 2.8 log10 CFU/m3, with 20 mg/L causing a reduction from 3.8 log10 CFU/m3 to 0 CFU/m3. The overall findings of this study indicate that SAEW may be a promising disinfectant agent either as a solution or spray. [ABSTRACT FROM AUTHOR]

Antibiotic resistance has become one of the major threats to global health. Photodynamic inactivation (PDI) develops little antibiotic resistance; thus, it becomes a promising strategy in the control of bacterial infection. During a PDI process, light-induced reactive oxygen species (ROS) damage the membrane components, leading to the membrane rupture and bacteria death. Due to the short half-life and reaction radius of ROS, achieving the cell-membrane intercalation of photosensitizers is a key challenge for PDI of bacteria. In this work, a tetraphenylethylenebased discrete organoplatinum(II) metallacycle (1) acts as a photosensitizer with aggregation-induced emission. It self-assembles with a transacting activator of transduction (TAT) peptide-decorated virus coat protein (2) through electrostatic interactions. This assembly (3) exhibits both ROS generation and strong membrane-intercalating ability, resulting in significantly enhanced PDI efficiency against bacteria. By intercalating in the bacterial cell membrane or entering the bacteria, assembly 3 decreases the survival rate of gramnegative Escherichia coli to nearly zero and that of gram-positive Staphylococcus aureus to ∼30% upon light irradiation. This study has wide implications from the generation of multifunctional nanomaterials to the control of bacterial infection, especially for gramnegative bacteria. [ABSTRACT FROM AUTHOR]

The wide application of chlorine disinfectant for drinking water treatment has led to the appearance of chlorine-resistant bacteria, which pose a severe threat to public health. This study was performed to explore the physiological-biochemical characteristics and environmental influence (pH, temperature, and turbidity) of seven strains of chlorine-resistant bacteria isolated from drinking water. Ozone disinfection was used to investigate the inactivation effect of bacteria and spores. The DNA concentration and cell surface structure variations of typical chlorine-resistant spores (Bacillus cereus spores) were also analysed by real-time qPCR, flow cytometry, and scanning electron microscopy to determine their inactivation mechanisms. The ozone resistance of bacteria (Aeromonas jandaei < Vogesella perlucida < Pelomonas < Bacillus cereus < Aeromonas sobria) was lower than that of spores (Bacillus alvei < Lysinibacillus fusiformis < Bacillus cereus) at an ozone concentration of 1.5 mg/L. More than 99.9% of Bacillus cereus spores were inactivated by increasing ozone concentration and treatment duration. Moreover, the DNA content of Bacillus cereus spores decreased sharply, but approximately 1/4 of the target genes remained. The spore structure exhibited shrinkage and folding after ozone treatment. Both cell structures and gene fragments were damaged by ozone disinfection. These results showed that ozone disinfection is a promising method for inactivating chlorine-resistant bacteria and spores in drinking water. Image 1 • Chlorine-resistant bacteria were easier to inactivate by ozone than spores. • Bacillus cereus spore inactivation rate reached 99.9% after ozone treatment. • O 3 disinfection inactivated spores by damaging cell surfaces and genetic material. [ABSTRACT FROM AUTHOR]

• ZnO NP–alginate beads revealed significant antibacterial effects. • The antibacterial mechanism involved the generation of reactive oxygen species. • The beads exhibited inactivation of bacteria in several consecutive cycles. • ZnO NP–alginate beads resulted in least leaching of zinc ions in water. Treating multidrug-resistant bacteria has been a challenging task, although the bacteria have been reported as a trace contaminant present in tap water. Given emerging issues on antibiotic-resistant bacteria, the present study investigated a novel treatment method in which ZnO nanoparticles (NPs) are encapsulated in an alginate biopolymer solution to explore primary antibacterial mechanisms. The antibacterial effects of this technology on two model antibiotic-resistant bacteria (Escherichia coli DH5-α and Pseudomonas aeruginosa) were found to be highly effective, with the removal rates of 98% and 88%, respectively, at the initial bacteria concentration of 108 CFU mL−1 over 6 h. The inactivation of antibiotic-resistant bacteria by ZnO NP–alginate beads was improved by increasing the nanocomposite amount (4, 10, and 20 mg) and contact time. The primary mechanism involved the generation of reactive oxygen species (ROS). The ZnO NP–alginate beads were demonstrated to be highly promising for different applications in water treatment, especially for point-of-use in the perspectives of reusability, antibacterial property of ZnO, immobilizing NPs, and utilizing high surface area of NPs, with a slight release of zinc ions. [ABSTRACT FROM AUTHOR]

For safety, designated Select Agents in tissues must be inactivated and viability tested before the tissue undergoes further processing and analysis. In response to the shipping of samples of "inactivated" Bacillus anthracis that inadvertently contained live spores to nonregulated entities and partners worldwide, the Federal Register now mandates in-house validation of inactivation procedures and standardization of viability testing to detect live organisms in samples containing Select Agents that have undergone an inactivation process. We tested and validated formaldehyde and glutaraldehyde inactivation procedures for animal tissues infected with virulent B. anthracis, Burkholderia pseudomallei, Francisella tularensis, and Yersinia pestis. We confirmed that our fixation procedures for tissues containing these Tier 1 Select Agents resulted in complete inactivation and that our validated viability testing methods do not interfere with detection of live organisms. Institutions may use this work as a guide to develop and conduct their own testing to comply with the policy. [ABSTRACT FROM AUTHOR]

Self-assembled functional nanomaterials with electromagnetic hot spots are crucial and highly desirable in surface-enhanced Raman scattering (SERS). Due to its versatile biological scaffold, the M13 phage has been employed to produce novel nano-building blocks and devices. In this study, we propose a novel M13 phage-based SERS nanocarrier, that utilizes the pVIII capsid in M13 to conjugate Au@Ag core-shell nanorod (Au@AgNR) with linker carboxy-PEG-thiol (M13-Au@AgNR) and the pIII capsid to specifically target Escherichia coli (E. coli). The M13-Au@AgNR@DTTC (3,3′- diethylthiocarbocyanine iodide) SERS probe was used to detect E. coli in a concentration range of 6 to 6 × 105 cfu/mL, achieving a limit of detection (LOD) of 0.5 cfu/mL. The proposed SERS platform was also tested in real samples, showing good recoveries (92%–114.3%) and a relative standard deviation (RSD) of 1.2%–4.7%. Furthermore, the system demonstrated high antibacterial efficiency against E. coli , approximately 90%, as measured by the standard plate-count method. The investigation provides an effective strategy for in vitro bacteria detection and inactivation. [ABSTRACT FROM AUTHOR]

Inactivation of bacteria in water is demonstrated by using the pulsed‐power method. A large number of micro bubbles are successfully produced by injecting the pulsed power into the water, and then, shock waves are generated with collapse of the bubbles and the instantaneous heating of the water. The synergistic effect of the shock waves, electric shock, and radicals produced by electrical discharge may enhance the inactivation of bacteria. Bacillus subtilis as bacteria are released into the water in a water vessel. We found that 97% of the bacteria are inactivated by firing 100 shots of the pulsed‐power injection. The gross energy efficiency for inactivation reaches (0.6–8.8) × 1012 CFU/kWh. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Abstract High intensity ultrasound is becoming important and more widely used in the food industry for microorganisms decontamination. This sterilization technique has been evaluated to improve food safety and to replace common processing with chemical additive compounds. The efficiency of a horn-type power ultrasound treatment (300 W and 600 W, 28 kHz, 10–30 min) on Listeria monocytogenes , Bacillus cereus , Escherichia coli , Salmonella typhimurium bacteria suspensions and phytoviruses was examined in this study. The results of this study showed that ultrasonic treatment can be used to eliminate vegetative cells of gram-positive and gram-negative bacteria from 1.59 to 3.4 log in bacterial suspensions and some phytoviruses in fruits. Highlights • The ultrasonic treatment caused a reduction of microorganisms vegetative cells. • Spores appear to be more resistant to the ultrasonic treatment that vegetative cells. • A 28 kHz, 600 W power ultrasound caused best reduction of pathogenic bacteria. • The ultrasonic treatment caused reduction of phytoviruses in fruits. [ABSTRACT FROM AUTHOR]

Waterborne pathogens, especially bacteria and viruses, pose significant health risks to the public, calling for the development of a sustainable, efficient, and robust disinfection strategy with reduced energy footprint and minimized byproduct formation. Here, we developed a sustainable photocatalytic composite for antimicrobial applications by integrating visible-light-responsive graphitic carbon nitride (g-C 3 N 4 ) with low-density porous expanded perlite (EP) mineral, and g-C 3 N 4 /EP-520 showed a high specific surface area of 45.3 m 2 /g and optimum performance for disinfection. g-C 3 N 4 /EP-520 achieved 8-log inactivation of E. coli and MS2 under 180 and 240 min visible-light irradiation without stirring, respectively. Water quality parameters were found to influence the disinfection performance of g-C 3 N 4 /EP-520: MS2 inactivation was promoted with the increase of dissolved oxygen (DO), proton concentration, salinity (NaCl), and hardness (Ca 2+ ). Importantly, g-C 3 N 4 /EP-520 could fully inactivate MS2 in a real source water sample with prolonged light irradiation, and negligible activity loss was observed in recycle use, demonstrating its viability and robustness for waterborne pathogen removal. Antimicrobial mechanisms of g-C 3 N 4 /EP-520 were systemically evaluated by radical scavenger addition, and revealed that the inactivation behavior was dependent on the type of microorganisms. Microscopic analyses confirmed that the destruction of bacterial cells and viral particles, leading to the inactivation of microorganisms. [ABSTRACT FROM AUTHOR]

The effect of high pressure thermal (HPT) treatments on the inactivation of spores of non-proteolytic type E Clostridium botulinum TMW 2.990 was investigated at high pressures (300 to 600 MPa) and elevated temperatures (80 to 100 °C) in four low-acid foods (steamed sole, green peas with ham, vegetable soup, braised veal) and imidazole phosphate buffer (IPB). In addition, corresponding conventional thermal treatments at ambient pressure were performed to expose possible synergisms of pressure and temperature on spore inactivation. In general, spore count reduction was more efficient by combining pressure and temperatures < 100 °C and the overall process duration could be shortened due to accelerated heating rates (adiabatic effect). Processing at 90 °C and 600 MPa resulted in inactivation below the detection limit after 5 min in all foods except steamed sole. Traditional thermal processing of spores at 90 °C for 10 min, on the other hand, did not result in an estimated 6-log reduction. Additional HPT treatments in steamed sole and IPB did not reveal pronounced food matrix dependent protective effects. Here, varying pressure levels did not appear to be the driving force for spore count reduction in steamed sole at any temperature. By applying a Weibull distribution on destruction kinetics of isobaric/isothermal holding times, 6D-values were calculated. Compression and decompression phase (1 s pressure holding time) had a considerable impact on spore count reduction (max. -2.9 log units) in both, foods and buffer. Hence, compression and decompression phases should directly be included into the total lethal effect of HPT treatments to avoid prolonged holding times and overprocessing. [ABSTRACT FROM AUTHOR]

Outbreaks of foodborne illness associated with berries often involve contamination with hepatitis A virus (HAV) and norovirus but also bacteria such as Escherichia coli O157:H7 and parasites such as Cyclospora caytanensis . We evaluated the applicability of UV-C to the inactivation of pathogens on strawberries, raspberries and blueberries. Our three-step approach consisted of assessing the chemical safety of UV-C-irradiated berries, evaluating the sensory quality after UV-C treatment and finally studying the inactivation of the target microorganisms. Treatments lasting up to 9 min (4000 mJ cm −2 ) did not produce detectable levels of furan (<5 μg/kg), a known photolysis product of fructose with genotoxic activity and thus were assessed to be toxicologically safe. No effect on taste or appearance was observed, unless treatment was excessively long. 20 s of treatment (an average fluence of ~ 212 mJ cm −2 ) reduced active HAV titer by >1 log 10 unit in 95% of cases except on frozen raspberries, while 120 s were required to inactivate murine norovirus to this extent on fresh blueberries. The mean inactivation of HAV and MNV was greater on blueberries (2–3 log 10 ) than on strawberries and raspberries (<2 log 10 ). MNV was more sensitive on fresh than on frozen berries, unlike HAV. Inactivation of Salmonella , E . coli O157:H7 and Listeria monocytogenes was poor on all three berries, no treatment reducing viable counts by >1 log 10 unit. In most matrices, prolonging the treatment did not improve the result to any significant degree. The effect was near its plateau after 20 s of treatment. These results provide insight into the effectiveness of UV-C irradiation for inactivating bacterial and viral pathogens and surrogates on fresh and frozen berries having different surface types, under different physical conditions and at different levels of contamination. Overall they show that UV-C as single processing step is unsuitable to inactivate significant numbers of foodborne pathogens on berries. [ABSTRACT FROM AUTHOR]

This study focused on the inactivation of bacterial growth using a mixture containing Salmonella enteritidis, Staphylococcus aureus, Bacillus cereus, and Escherichia coli. This bacterial mixture was added to chicken eggshells and subsequently targeted for elimination using two types of silver nanoparticle (Ag-NP) delivery systems: a composite film (named cover) and a colloidal spray. Both systems were applied to the eggshells' packaging at concentrations of 500, 1000, and 2000 ppm over 28 days. A General Linear Model (GLM), repeated measurement-Analysis of Variance (ANOVA) procedure was used to analyse the effect of time and concentration of the Ag-NP materials on the inactivation of bacteria. The maximum reduction of bacterial growth resulted from the "Spray 2000 ppm", for which the value of the bacteria reached a minimum (0.93 ± 0.42) on day 7, and was calculated to be undetected on days 14 and 28, followed by Spray 1000 ppm. In other words, increasing the concentration of the Ag-NP in both coatings, either spray or cover, significantly decreased the number of bacteria colonies on the eggshells. However, the effect of packaging with different concentrations of nanocomposites and the length of the study (number of days) did not show statistically significant results. [ABSTRACT FROM AUTHOR]

In this study, we investigated the inactivation efficacy of endospore-forming bacteria, Bacillus pumilus, irradiated by low-energy X-rays of different beam qualities. The different low-energy X-rays studied had cut-off energies of 50, 100 and 150 keV. Bacillus pumilus spores (in biological indicator strips) were irradiated at step doses between 6.5 to 390 Gy. The resulting bacteria populations were then quantified by a pour plate method. Results showed that X-rays of lower energies were more effective in inactivating bacterial spores. In addition, an increment in bacterial population was observed at doses below 13Gy. We attributed this increase to a radiation-induced activation of bacterial spores. Four kinetic models were then evaluated for their prediction of bacterial spore behavior under irradiation. This included: (i) first-order kinetics model; (ii) Shull model; (iii) Sapru model; and (iv) probabilistic model. From R2 and AIC analyses, we noted that the probabilistic model performed the best, followed by the Sapru model. We highlighted that for simplicity in curve fitting the Sapru model should be used instead of the probabilistic model. A 12-log reduction in bacterial population (corresponding to a sterility assurance level of 10−6 as required in the sterilization of medical devices) was computed to be achievable at doses of 1000, 1600 and 2300 Gy for the three different X-ray cut-off energies respectively. These doses are an order in magnitude lesser than that required in gamma irradiation. This highlights the applicability of cheaper and safer table-top X-ray sources for sterilization application. [ABSTRACT FROM AUTHOR]