Genetic Factors Affect the Survival and Behaviors of Selected Bacteria during Antimicrobial Blue Light Treatment.

Antimicrobial resistance is a global, mounting and dynamic issue that poses an immediate threat to human, animal, and environmental health. Among the alternative antimicrobial treatments proposed to reduce the external use of antibiotics is electromagnetic radiation, such as blue light. The prevailing mechanistic model is that blue light can be absorbed by endogenous porphyrins within the bacterial cell, inducing the production of reactive oxygen species, which subsequently inflict oxidative damages upon different cellular components. Nevertheless, it is unclear whether other mechanisms are involved, particularly those that can affect the efficacy of antimicrobial blue light treatments. In this review, we summarize evidence of inherent factors that may confer protection to a selected group of bacteria against blue light-induced oxidative damages or modulate the physiological characteristics of the treated bacteria, such as virulence and motility. These include descriptions of three major photoreceptors in bacteria, chemoreceptors, SOS-dependent DNA repair and non-SOS protective mechanisms. Future directions are also provided to assist with research efforts to increase the efficacy of antimicrobial blue light and to minimize the development of blue light-tolerant phenotypes.

Effect of low power lasers on prokaryotic and eukaryotic cells under different stress condition: a review of the literature.

Radiations emitted by low power radiation sources have been applied for therapeutic proposals due to their capacity of inactivating bacteria and cancer cells in photodynamic therapy and stimulating tissue cells in photobiomodulation. Exposure to these radiations could increase cell proliferation in bacterial cultures under stressful conditions. Cells in infected or not infected tissue injuries are also under stressful conditions and photobiomodulation-induced regenerative effect on tissue injuries could be related to effects on stressed cells. The understanding of the effects on cells under stressful conditions could render therapies based on photobiomodulation more efficient as well as expand them. Thus, the objective of this review was to update the studies reporting photobiomodulation on prokaryotic and eukaryotic cells under stress conditions. Exposure to radiations emitted by low power radiation sources could induce adaptive responses enabling cells to survive in stressful conditions, such as those experienced by bacteria in their host and by eukaryotic cells in injured tissues. Adaptive responses could be the basis for clinical photobiomodulation applications, either considering their contraindication for treatment of infected injuries or indication for treatment of injuries, inflammatory process resolution, or tissue regeneration.

Water UV-C treatment alone or in combination with peracetic acid: A technology to maintain safety and quality of strawberries.

Disinfection of fruits is one of the most important steps since they are going to be eaten fresh-or minimally-processed. This step affects quality, safety, and shelf-life of the product. Despite being a common sanitizer in the fruit industry, chlorine may react with organic matter leading to the formation of toxic by-products. Alternative sustainable disinfection strategies to chlorine are under study to minimize environmental and human health impact. Water-assisted UV-C light (WUV-C) is proposed here as an alternative sanitizing method for strawberries. In this study, strawberries were washed for 1 or 5 min in a tank with 2 or 4 lamps on, each emitting UV-C light at 17.2 W/cm2, or in a chlorine solution (200 ppm, pH 6.5). Moreover, trials with 4 lamps on, together with a washing solution consisting on peracetic acid at 40 or 80 ppm, were carried out. Overall, quality and nutritional parameters of strawberries after treatments were maintained. Changes in color were not noticeable and fruits did not lose firmness. No major changes were observed in antioxidant activity, organic acid, anthocyanin, vitamin C, and total phenolic content. Yeasts and molds were not affected by the WUV-C treatment, and 5 min were needed to significantly reduce total aerobic mesophylls population. However, reductions of artificially inoculated Listeria innocua and Salmonella Typhimurium after WUV-C treatments were comparable to those obtained with chlorine-wash, which were 3.0 log CFU / g. Moreover, WUV-C light was effective to minimize microorganisms remaining in washing water, avoiding cross-contamination and thus, allowing water recirculation. This effect was improved when combining the action of UV-C light with peracetic acid, showing the suitability of this combined treatment, understood as an alternative to chlorine sanitation, for sanitizing strawberries and keeping the populations of pathogenic bacteria in washing water lower than 0.6 ±â€¯0.1 log CFU / mL.

Photobiomodulation modulates inflammation and oral microbiome: a pilot study.

INTRODUCTION: Oral mucositis (OM) is a severe side effect in patients undergoing anticancer therapies, which negatively impacts on their quality of life often leading to either the interruption of the therapy. Photobiomodulation (PBM) is emerging as an effective strategy allowing a faster wound healing. OBJECTIVES: This pilot study aims at verifying whether PBM modulates the inflammatory response in patients and its effect on the oral microbiome composition. MATERIALS AND METHODS: Buccal swabs were collected from four patients affected by OM, both on ulcerated and clinically healthy areas, before and on the last day of PBM therapy, as well as on the first day after treatment discontinuation. The concentration of 38 cytokines and the composition of oral microbiome were measured. RESULTS: Most of the pro-inflammatory cytokines were reduced, whereas anti-inflammatory cytokines resulted up-regulated by PBM. In addition, PBM influenced the composition of oral microbiome, by decreasing the amount of pathogenic species and promoting the growth of commensal bacteria. These changes were even more evident when separately analysing patients who clinically responded to PBM and the only patient who did not respond. CONCLUSIONS: PBM reduces inflammatory burden in patients affected by OM and positively influences the composition of the oral microbiome.

Ultraviolet A light effectively reduces bacteria and viruses including coronavirus.

Antimicrobial-resistant and novel pathogens continue to emerge, outpacing efforts to contain and treat them. Therefore, there is a crucial need for safe and effective therapies. Ultraviolet-A (UVA) phototherapy is FDA-approved for several dermatological diseases but not for internal applications. We investigated UVA effects on human cells in vitro, mouse colonic tissue in vivo, and UVA efficacy against bacteria, yeast, coxsackievirus group B and coronavirus-229E. Several pathogens and virally transfected human cells were exposed to a series of specific UVA exposure regimens. HeLa, alveolar and primary human tracheal epithelial cell viability was assessed after UVA exposure, and 8-Oxo-2'-deoxyguanosine was measured as an oxidative DNA damage marker. Furthermore, wild-type mice were exposed to intracolonic UVA as an in vivo model to assess safety of internal UVA exposure. Controlled UVA exposure yielded significant reductions in Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, Clostridioides difficile, Streptococcus pyogenes, Staphylococcus epidermidis, Proteus mirabilis and Candida albicans. UVA-treated coxsackievirus-transfected HeLa cells exhibited significantly increased cell survival compared to controls. UVA-treated coronavirus-229E-transfected tracheal cells exhibited significant coronavirus spike protein reduction, increased mitochondrial antiviral-signaling protein and decreased coronavirus-229E-induced cell death. Specific controlled UVA exposure had no significant effect on growth or 8-Oxo-2'-deoxyguanosine levels in three types of human cells. Single or repeated in vivo intraluminal UVA exposure produced no discernible endoscopic, histologic or dysplastic changes in mice. These findings suggest that, under specific conditions, UVA reduces various pathogens including coronavirus-229E, and may provide a safe and effective treatment for infectious diseases of internal viscera. Clinical studies are warranted to further elucidate the safety and efficacy of UVA in humans.

Mechanistic insights into UV-A mediated bacterial disinfection via endogenous photosensitizers.

UV-A and visible light are thought to excite endogenous photosensitizers in microbes, thereby initiating complex chemical interactions that ultimately kill cells. Natural solar-based disinfection methods have been adapted into commercial lighting technologies with varying degrees of reported efficacy and associated safety hazards for human exposure. Here we utilize a narrow-spectrum UV-A LED prototype (currently in development for health care applications) to investigate the mechanism of bacterial photoinactivation using 365 nm light. Using a combination of reverse genetics and biochemical investigation, we report mechanistic evidence that 365nm light initiates a chain-reaction of superoxide-mediated damage via auto-excitation of vitamin-based electron carriers, specifically vitamin K2 menaquinones and the FAD flavoprotein in Complex II in the electron transport chain. We observe that photoinactivation is modifiable through supplementation of the environment to bypass cell damage. Lastly, we observe that bacteria forced into metabolic dormancy by desiccation become hypersensitized to the effects of UV-A light, thereby permitting photoinactivation at fluences that are significantly lower than the industry threshold for safe human exposure. In total, these results substantiate the mechanism and potential application of narrow- spectrum UV-A light for bacterial disinfection purposes.

Microbial acetylcholinesterase inhibitors for Alzheimer's therapy: recent trends on extraction, detection, irradiation-assisted production improvement and nano-structured drug delivery.

Neurodegenerative disorders especially Alzheimer's disease (AD) are significantly threatening the public health. Acetylcholinesterase (AChE) inhibitors are compounds of great interest which can be used as effective agents for the symptomatic treatment of AD. Although plants are considered the largest source for these types of inhibitors, the microbial production of AChE inhibitors represents an efficient, easily manipulated, eco-friendly, cost-effective, and alternative approach. This review highlights the recent advances on the microbial production of AChE inhibitors and summarizes all the previously reported successful studies on isolation, screening, extraction, and detecting methodologies of AChE inhibitors from the microbial fermentation, from the earliest trials to the most promising anti-AD drug, huperzine A (HupA). In addition, improvement strategies for maximizing the industrial production of AChE inhibitors by microbes will be discussed. Finally, the promising applications of nano-material-based drug delivery systems for natural AChE inhibitor (HupA) will also be summarized. KEY POINTS: • AChE inhibitors are potential therapies for Alzheimer's disease. • Microorganisms as alternate sources for prospective production of such inhibitors. • Research advances on extraction, detection, and strategies for production improvement. • Nanotechnology-based approaches for an effective drug delivery for Alzheimer's disease.

A powerful combination of copper-cysteamine nanoparticles with potassium iodide for bacterial destruction.

Herein, for the first time, we demonstrate that the combination of copper-cysteamine (Cu-Cy) nanoparticles (NPs) and potassium iodide (KI) can significantly inactivate both Gram-positive MRSA and Gram-negative E. coli. To uncover the mystery of the killing, the interaction of KI with Cu-Cy NPs was investigated systematically and the products from their interaction were identified. No copper ions were released after adding KI to Cu-Cy NPs in cell-free medium and, therefore, it is reasonable to conclude that the Fenton reaction induced by copper ions is not responsible for the bacterial killing. Based on the observations, we propose that the major killing mechanism involves the generation of toxic species, such as hydrogen peroxide, triiodide ions, iodide ions, singlet oxygen, and iodine molecules. Overall, the powerful combination of Cu-Cy NPs and KI has good potential as an independent treatment or a complementary antibiotic treatment to infectious diseases.

Uncoupled phytoplankton-bacterioplankton relationship by multiple drivers interacting at different temporal scales in a high-mountain Mediterranean lake.

Global-change stressors act under different timing, implying complexity and uncertainty in the study of interactive effects of multiple factors on planktonic communities. We manipulated three types of stressors acting in different time frames in an in situ experiment: ultraviolet radiation (UVR); phosphorus (P) concentration; temperature (T) in an oligotrophic Mediterranean high-mountain lake. The aim was to examine how the sensitivity of phytoplankton and bacterioplankton to UVR and their trophic relationship change under nutrient acclimation and abrupt temperature shifts. Phytoplankton and bacteria showed a common pattern of metabolic response to UVR × P addition interaction, with an increase in their production rates, although evidencing an inhibitory UVR effect on primary production (PP) but stimulatory on bacterial production (HBP). An abrupt T shift in plankton acclimated to UVR and P addition decreased the values of PP, evidencing an inhibitory UVR effect, whereas warming increased HBP and eliminated the UVR effect. The weakening of commensalistic and predatory relationship between phyto- and bacterioplankton under all experimental conditions denotes the negative effects of present and future global-change conditions on planktonic food webs towards impairing C flux within the microbial loop.

Photobiomodulation via multiple-wavelength radiations.

Photobiomodulation via a combination of different radiations can produce different effects on biological tissues, such as cell proliferation and differentiation, when compared to those produced via a single radiation. The present study aims to conduct a review of the literature addressing the results and applications of photobiomodulation induced by a combination of two or more radiations as well as their possible effects. PubMed was used to search for studies with restrictions on the year (< 50 years old) and language (English), including studies using human and animal models, either under healthy or pathologic conditions. Several studies have been conducted to evaluate the combination of different radiation effects on cells and biological tissues. Positive effects resulting from multiple-wavelength radiations could be attributed to different absorption levels because superficial and deep tissues could absorb different levels of radiations. Multiple-wavelength radiations from devices combining radiations emitted by low power lasers and light-emitting diodes could be a new approach for promoting photobiomodulation-induced beneficial effects.

Photobiomodulation by dual-wavelength low-power laser effects on infected pressure ulcers.

The aim of this study was to evaluate the effects of photobiomodulation (PBM) by dual-wavelength low-power lasers on the healing and bacterial bioburden of pressure ulcer (PU) models. Twenty-five male Swiss mice were divided into five equal groups. Ischemia reperfusion cycles were employed to cause PU formation by the external application of magnetic plates. Immediately after wounding, a suspension of Pantoea agglomerans was applied at the base of all the wounds of the infected groups, using a calibrated pipette. PBM (simultaneous emission at 660 and 808 nm, 142.8 J/cm2, in continuous wave emission mode) was applied to the PUs for 14 sessions. The animals were euthanized 14 days after PU induction, and their tissues were analyzed for wound contraction and reepithelialization, epidermis thickness, bacterial survival, and IL-1ß and IL-10 mRNA level evaluations. The PU areas appeared larger in the mice from the infected groups than in those in the laser group 4 days after PU induction and presented incomplete reepithelialization 14 days after PU induction. However, the PBM accelerated the wound healing in the infected + laser group compared with the infected group 11 and 14 days following the PU induction. The infected and irradiated PUs exhibited a thinner neo-epidermis than those in the infected group, and the bacterial survival decreased in the laser group; the relative expression IL-1ß mRNA levels demonstrated an increasing tendency while the relative expression IL-10 mRNA levels demonstrated a decreasing tendency in the infected + laser and laser groups. These results suggest that PBM improves healing by killing or inhibiting bacteria in PUs as well as by accelerating the wound healing, resulting in tissue repair.

Photo-inactivation of bacteria in hospital effluent via thiolated iron-doped nanoceria.

Hospital wastewater is a major contributor of disease-causing microbes and the emergence of antibiotic resistant bacteria. In this study, thiolated iron-doped nanoceria was synthesised and tested for killing of microbes from hospital effluent. These particles were designed to inhibit the efflux pumps of the bacteria found in hospital effluent with further ability to activate in visible light via iron doping thus generating tunable amount of reactive oxygen species (ROS). The quantum yield of the ROS generated by the nanoceria was 0.67 while the ROS types produced were singlet oxygen (36%), hydroxyl radical (31%) and hydroxyl ions (32%), respectively. The particles were initially synthesised through green route using Foeniculum vulgare seeds extract and were annealed at 200°C and further coated with thiolated chitosan to enhance the solubility and efflux pump inhibition. X-ray diffraction confirmed the polycrystalline nature of nanoparticles and uniform spherical shape with 30 nm size, confirmed by scanning electron microscope. The nanoparticles exhibited 100% bactericidal activity at 100 µg/mL against all the isolated bacteria. The enhanced bactericidal effect of iron-doped nanoceria could be attributed to efflux inhibition via thiolated chitosan as well as the production of ROS upon illumination in visible light, causing oxidative stress against microbes found in hospital effluent.

A shared core microbiome in soda lakes separated by large distances.

In alkaline soda lakes, concentrated dissolved carbonates establish productive phototrophic microbial mats. Here we show how microbial phototrophs and autotrophs contribute to this exceptional productivity. Amplicon and shotgun DNA sequencing data of microbial mats from four Canadian soda lakes indicate the presence of > 2,000 species of Bacteria and Eukaryotes. We recover metagenome-assembled-genomes for a core microbiome of < 100 abundant bacteria, present in all four lakes. Most of these are related to microbes previously detected in sediments of Asian alkaline lakes, showing that common selection principles drive community assembly from a globally distributed reservoir of alkaliphile biodiversity. Detection of > 7,000 proteins show how phototrophic populations allocate resources to specific processes and occupy complementary niches. Carbon fixation proceeds by the Calvin-Benson-Bassham cycle, in Cyanobacteria, Gammaproteobacteria, and, surprisingly, Gemmatimonadetes. Our study provides insight into soda lake ecology, as well as a template to guide efforts to engineer biotechnology for carbon dioxide conversion.

Violet-Blue Light Arrays at 405 Nanometers Exert Enhanced Antimicrobial Activity for Photodisinfection of Monomicrobial Nosocomial Biofilms.

Light-emitting diodes (LEDs) demonstrate therapeutic effects for a range of biomedical applications, including photodisinfection. Bands of specific wavelengths (centered at 405 nm) are reported to be the most antimicrobial; however, there remains no consensus on the most effective irradiation parameters for optimal photodisinfection. The aim of this study was to assess decontamination efficiency by direct photodisinfection of monomicrobial biofilms using a violet-blue light (VBL) single-wavelength array (SWA) and multiwavelength array (MWA). Mature biofilms of nosocomial bacteria (Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus) were grown on 96-well polypropylene PCR plates. The biofilms were then exposed to VBL for 2,700 s (SWA) and 1,170 s (MWA) to deliver 0 to 670 J/cm2, and the antibacterial activity of VBL was assessed by comparing the seeding of the irradiated and the nonirradiated biofilms. Nonirradiated groups were used as controls. The VBL arrays were characterized optically (spectral irradiance and beam profile) and thermally. The SWA delivered 401-nm VBL and the MWA delivered between 379-nm and 452-nm VBL, albeit at different irradiances and with different beam profiles. In both arrays, the irradiated groups were exposed to increased temperatures compared to the nonirradiated controls. All bacterial isolates were susceptible to VBL and demonstrated reductions in the seeding of exposed biofilms compared with the nonirradiated controls. VBL at 405 nm exerted the most antimicrobial activity, exhibiting reductions in seeding of up to 94%. Decontamination efficiency is dependent on the irradiation parameters, bacterial species and strain, and experimental conditions. Controlled experiments that ameliorate the heating effects and improve the optical properties are required to optimize the dosing parameters to advance the successful clinical translation of this technology.IMPORTANCE This study reports the efficacy of VBL and blue light (BL) and their antimicrobial activity against mature biofilms of a range of important nosocomial pathogens. While this study investigated the antibacterial activity of a range of wavelengths of between 375 and 450 nm and identified a specific wavelength region (∼405 nm) with increased antibacterial activity, decontamination was dependent on the bacterial species, strain, irradiation parameters, and experimental conditions. Further research with controlled experiments that ameliorate the heating effects and improve the optical properties are required to optimize the dosing parameters to advance the successful clinical translation of this technology.

Storage stability of soluble pigments, chlorophylls, and carotenoids in electron-beam-irradiated edible lavers (Porphyra umbilicalis) with impact on microbial safety and sensory characteristics.

BACKGROUND: In this study, we investigated whether electron beam (e-beam) irradiation can inactivate microbial populations, including aerobic bacteria plate count, fungi, and coliforms, in two types of lavers (dried and roasted). The impact of e-beam doses of 4 and 7 kGy on microbial populations, color values, total soluble pigments, chlorophylls, and carotenoid content immediately and after storage at 4, 15, 25, and 35 °C for 4, 8, and 12 weeks was also evaluated. RESULTS: The initial microbial load of approximately 106 and 105 CFU g-1 in both dried and roasted lavers was reduced to 104 and 101 CFU g-1 , respectively, after irradiation at 7 kGy. No further proliferation was observed in irradiated dried lavers during 4 weeks of storage at 4 and 15 °C. When stored at low temperature, the shelf-life was extended for up to 12 weeks in 7 kGy irradiated dried and roasted lavers. High amounts of soluble pigments and carotenoids were observed during storage in the 7 kGy irradiated dried laver samples at the end of 12 weeks irrespective of temperature. Although the chlorophyll content decreased under the storage conditions, it was comparatively stable in the 7 kGy-irradiated dried laver. Maximum degradation of color was observed in laver samples subjected to the roasting process. CONCLUSION: Overall, this study indicated that e-beam irradiation of laver at 7 kGy maintains microbial safety as well as quality attributes during storage for up to 12 weeks. Further, dried laver had more essential compounds than roasted laver. © 2019 Society of Chemical Industry.

Blue light-emitting diode in healthy vaginal mucosa-a new therapeutic possibility.

A healthy female genital mucosa has an ecosystem that remains in balance through interactions between endogenous and exogenous factors. The light-emitting diode (LED) is a device that emits light at different wavelengths, with varying color and effects. Blue light in humans is most commonly used for antimicrobial purposes and has been already applied to treat facial acne and gastric bacteria. Although blue LED therapy in humans has been reported, its properties against vaginal infections have not yet been investigated. This study aims to test the safety and effects of 401 ± 5 nm blue LED on healthy vaginal mucosa. Phase I clinical trial involving 10 women between 18 and 45 years old with healthy vaginal mucosa. The participants were illuminated by 401 ± 5 nm blue LED for 30 min and anamnesis, oncotic cytology, and pH measurement were made again after 21/28 days of treatment. In the re-evaluation, adverse effects were investigated. The mean age was 27 ± 5.4 years and one of the women was excluded due to interruption of use of oral contraceptives. Oncotic cytology done before and after therapy showed that the composition of the microflora remained normal in all participants. Vaginal pH remained unchanged in eight of the women and had a reduction in one woman (5.0-4.0). No adverse effects were observed during or after illumination. 401 ± 5 nm blue LED did not generate any adverse effects or pathogenic changes in the microflora and vaginal pH. The effects of 401 ± 5 nm blue LED still need to be tested in vulvovaginal pathogens. Trial registration number: NCT03075046.

Antimicrobial Photoinactivation Using Visible Light Plus Water-Filtered Infrared-A (VIS + wIRA) and Hypericum Perforatum Modifies In Situ Oral Biofilms.

Due to increasing antibiotic resistance, the application of antimicrobial photodynamic therapy (aPDT) is gaining increasing popularity in dentistry. The aim of this study was to investigate the antimicrobial effects of aPDT using visible light (VIS) and water-filtered infrared-A (wIRA) in combination with a Hypericum perforatum extract on in situ oral biofilms. The chemical composition of H. perforatum extract was analyzed using ultra-high-performance liquid chromatography coupled with high resolution mass spectrometry (UPLC-HRMS). To obtain initial and mature oral biofilms in situ, intraoral devices with fixed bovine enamel slabs (BES) were carried by six healthy volunteers for two hours and three days, respectively. The ex situ exposure of biofilms to VIS + wIRA (200 mWcm-2) and H. perforatum (32 mg ml-1, non-rinsed or rinsed prior to aPDT after 2-min preincubation) lasted for five minutes. Biofilm treatment with 0.2% chlorhexidine gluconate solution (CHX) served as a positive control, while untreated biofilms served as a negative control. The colony-forming units (CFU) of the aPDT-treated biofilms were quantified, and the surviving microorganisms were identified using MALDI-TOF biochemical tests as well as 16 S rDNA-sequencing. We could show that the H. perforatum extract had significant photoactivation potential at a concentration of 32 mg ml-1. When aPDT was carried out in the presence of H. perforatum, all biofilms (100%) were completely eradicated (p = 0.0001). When H. perforatum was rinsed off prior to aPDT, more than 92% of the initial viable bacterial count and 13% of the mature oral biofilm were killed. Overall, the microbial composition in initial and mature biofilms was substantially altered after aPDT, inducing a shift in the synthesis of the microbial community. In conclusion, H. perforatum-mediated aPDT using VIS + wIRA interferes with oral biofilms, resulting in their elimination or the substantial alteration of microbial diversity and richness. The present results support the evaluation of H. perforatum-mediated aPDT for the adjunctive treatment of biofilm-associated oral diseases.

Effect of catalytic infrared dry-blanching on the processing and quality characteristics of garlic slices.

This study investigates the effects of catalytic infrared (CIR) dry-blanching (CIRDB) on the processing and quality of garlic slices. CIRDB processing parameters of CIR processing temperature, slice thickness and processing time were studied versus the processing characteristics of internal temperature, peroxidase (POD) activity and moisture reduction. Blanched garlic quality characteristics of surface color change (ΔE), allicin retention rate, vitamin C retention rate and microbial content were determined. Hot water blanching (WB) was used as a comparison. The results indicated that increasing CIR processing temperature and/or reducing the slice thickness accelerated internal temperature rise and POD inactivation and moisture reduction. To achieve 90% inactivation of POD, the CIRDB treatment resulted in moisture reductions of 15.87-40.37%, microbial reductions of 1.76-3.91-log, ΔE between 2.03 and 10.01, retention rate of allicin between 10.63 and 33.31%, and retention rate of vitamin C between 55.00 and 81.13%. CIRDB achieved the high-quality garlic products compared with WB.

Solution-Processable Two-Dimensional In2 Se3 Nanosheets as Efficient Photothermal Agents for Elimination of Bacteria.

Two-dimensional (2D) nanoflakes represent an appealing class of materials for optoelectronics applications due to their unique layered structures and excellent electronic properties. However, the lack of easy-to-manipulate and effective methods for large-scale production of these 2D materials limits their potential for applications. Also, few efforts have been made to explore their applications in biological fields. This work reports the preparation of large quantities of 2D In2 Se3 nanosheets through a solvent exfoliation technique. Transmission electron microscopy and atomic force microscopy results show that the In2 Se3 nanosheets are obtained with lateral sizes of tens of nanometers to hundreds of nanometers and thickness of 2-17 layers. Raman features coupled with the X-ray diffractometry results unequivocally confirm the as-prepared In2 Se3 nanosheets to be α phase. Moreover, these α-In2 Se3 nanosheets exhibit an excellent near-infrared (NIR) photothermal performance under an 808 nm laser irradiation. NIR photo-excitation of the α-In2 Se3 nanosheets in the presence of bacteria leads to a significant antibacterial effect, suggesting that these nanosheets have great potential to be photothermal antibacterial agents. Our work on α-In2 Se3 nanosheets presents an available method for exfoliating 2D layered materials, and highlights the potential application in chemical and biological fields of α-In2 Se3 nanosheets.

Inactivation of some pathogenic bacteria and phytoviruses by ultrasonic treatment.

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.