Log Reduction Research Articles

Cold Plasma and Pulsed Light Inactivates Escherichia coli O157: H7 in Romaine Lettuce and Preserves Produce Quality

ABSTRACTFresh produce safety is important for consumer health. Intervention technologies that can lessen the pathogen threat and produce contamination is needed. In this research, cold plasma (CP), pulsed light (PL) and their combinations were assessed for inactivating Escherichia coli O157:H7 on Romaine lettuce. The effects of treatment on native microflora and sensory attributes of lettuce was also determined. An inoculum of multiple E. coli O157:H7 strains was employed for this study. Lettuce leaves were spot inoculated and then treated with PL (1–60 s), CP (15–60 s) or their optimized treatment combinations. A 30 s treatment with PL (fluence dose of 31.5 J/cm2), was optimum which provided 2.7 log CFU/g reduction of the pathogen, while 45 s treatment of CP was optimum, that delivered 2.1 log CFU/g log reduction. Combinations of PL and CP treatments were investigated for enhanced inactivation. For PL‐CP combination, inoculated lettuce was treated with PL for 30 s followed by 45 s of CP exposure. While for CP‐PL combination, treatments sequences were 45 s of CP treatment followed by 30 s PL treatment. Both combination treatments, PL‐CP and CP‐PL, resulted in synergistic inactivation of E. coli cells with > 5 log reductions of the pathogen. These combination treatments significantly (p < 0.05) reduced native microbiota and slowed their growth during storage. Additionally, treatment effects on lettuce quality was not adversely impacted. PL and CP are both non‐aqueous, sustainable technologies. This study demonstrated that integration of PL and CP technology can enhance microbial safety and preserve quality of Romaine lettuce.

Polyethersulfone mixed matrix membranes modified with pore formers and Ag-titanate nanotubes: physicochemical characteristics and (bio)fouling study.

In the presented studies it was hypothesized that the modification of a polymeric membrane with a pore former and a hybrid nanomaterial composed of titanate nanotubes with deposited Ag nanoparticles (Ag-TNTs NPs) can protect the membrane from the microbial growth, and thus enhance its resistance to biofouling. Polyethersulfone (PES) membranes were prepared by the wet phase inversion, and polyvinylpyrrolidone (PVP) and poly(ethylene glycol) (PEG) were used as pore formers. The membranes were characterized in terms of morphology, topography, permeability, separation characteristics, and anti-(bio)fouling properties as well as antibacterial activity. The membranes modified with porogens and Ag-TNTs revealed improved hydrophilicity and water permeability compared to the unmodified membrane, from 58 to 66%. Moreover, the improvement in rejection of model dextrans and PEG upon application of the NPs was found. However, the use of PVP or PEG had a negative influence on the resistance to fouling by bovine serum albumin, i.e., ca. 35% of decline of permeate flux was noticed after 2h of ultrafiltration of BSA. On the contrary, both porogens and NPs contributed to biofouling mitigation. The introduction of pore formers had a positive effect on the inhibition of Escherichia coli growth by the membrane containing Ag-TNTs. The log reduction of bacteria varied from 3.17 to 3.3 in case of stirred and filtration system.

Synergistic antibacterial effect of 405 nm blue light-emitting diodes (LEDs) and gelatin film for inactivation of Escherichia coli O157:H7 and Salmonella Typhimurium on stainless steel and fresh fruit peel

A combined antibacterial effect of 405 nm blue LEDs (BL) and gelatin film (G) was investigated on stainless steel (SUS) and fresh fruit peel for the inactivation of Escherichia coli O157:H7 and Salmonella Typhimurium. On the SUS, the sum of the individual treatments of G for 20 min and BL at 20 J/cm2 was <1 log reduction (log CFU/cm2). In comparison, combination treatment of G and BL (G + BL) at 20 J/cm2 exhibited 2.37 and 3.09 log reduction on E. coli O157:H7 and S. Typhimurium. The G + BL treatment only increased a propidium iodide (PI) uptake, indicating that cell membrane damage occurred. In the G + BL treatment, reactive oxygen species (ROS) scavenging assay confirmed that ROS involved in the bactericidal mechanism. On orange peel, the G + BL treatment at 40 J/cm2 resulted in a 3.05 and 3.17 log reduction on E. coli O157:H7 and S. Typhimurium. In contrast, the individual treatment of G for 40 min led to reductions of 0.63 log CFU/cm2 for E. coli O157:H7 and 0.50 log CFU/cm2 for S. Typhimurium, while the BL treatment at 40 J/cm2 achieved reductions of 0.78 and 0.69 log CFU/cm2, respectively. A synergistic bactericidal effect was similarly observed in the combined treatment groups for both apple and grapefruit peels. In a color and texture analysis, G did not affect hardness, toughness, and visual color of fruit.

The Power of Thermosonication on Quality Preservation and Listeria Control of Blueberry Juice

Due to the increasing consumer demand for healthy, beneficial foods, natural fruit juices have gained popularity for their rich nutritional value and appealing flavor. However, traditional thermal processing can compromise these quality attributes. This study investigates using pulsed thermosonication, a novel mild thermal processing method, on Listeria innocua inactivation in blueberry juice, chosen for its high phenolic and anthocyanin content. Ultrasonication was applied at 60% and 100% amplitudes combined with heat treatments at 45 °C and 55 °C and compared to control heat treatments. The Weibull model effectively described the inactivation kinetics, showing that the thermosonicated samples required significantly shorter times (1 and 25 min) for a 5-log reduction compared to the heated samples (10 and 60 min). While pH, total soluble solids, and water activity remained unaffected, color parameters improved, and the best retention of phenolics and anthocyanins was observed at 100% amplitude and 45 °C. Rheological properties were unchanged. The findings demonstrate that thermosonication at milder temperatures is more effective than conventional heat treatment for microbial inactivation and quality retention in blueberry juice, suggesting it is a superior processing method for preserving fruit juices’ nutritional and sensory attributes.

Probiotication of Plum Pulp and Conditions Effects Freeze-Drying in Cell Viability, Functional Properties and Antioxidant Activity

This study investigated the effects of fermenting plum pulp with Bifidobacterium animalis ssp. lactis (BAL) on its physicochemical and bioactive properties, as well as the optimization of the freeze-drying (FD) process to develop a fruit-based probiotic delivery system. Fermentation significantly reduced the pH and total acidity of the pulp, achieving a cell viability of 11 log CFU/mL. The FD process was optimized using a factorial design, with maltodextrin concentration (3, 5, and 7%) and freezing temperature (−150, −100, and −50 °C) as variables. The P2 experiment, which used 7% maltodextrin and freezing at −150 °C, showed the best results in terms of yield (25.67%), cell viability (8 log CFU/g), and probiotic survival rate (97.66%). Samples P5, P6, and P7, prepared with 5% maltodextrin and freezing at −100 °C, exhibited the highest levels of bioactive compounds and antioxidant activity (p &lt; 0.05). During 28 days of storage, all samples maintained cell viability without significant logarithmic reduction. In summary, probiotic plum powders offer an excellent plant-based alternative for probiotic consumption, providing safe levels of beneficial bacteria and bioactive compounds with antioxidant action, meeting health and nutrition needs.

Inhibitory Effect of DNase–Chitosan–Nisin Nanoparticles on Cell Viability, Motility, and Spatial Structures of Listeria monocytogenes Biofilms

Listeria monocytogenes biofilm contamination on food contact surfaces is a major concern for the food industry. Nanoparticle encapsulation appears as a novel strategy for food surface disinfection to prevent biofilm formation. Chitosan nanoparticles loaded with nisin and DNase I (DNase-CS-N) have been constructed to exhibit antimicrobial activity against L. monocytogenes. This study aimed to investigate their ability to inhibit L. monocytogenes biofilm formation and eliminate preformed biofilms on food contact surfaces (polystyrene, polyurethane, and stainless steel). DNase-CS-N could decrease 99% and 99.5% biofilm cell numbers at 1/2 MIC and MIC, respectively. At sub-MICs, DNase-CS-N could reduce cell motility (swimming and swarming) and slime production of L. monocytogenes. In terms of effect on biofilm elimination, DNase-CS-N at the concentration of 4 MIC led to 3–4 log reduction in biofilm cells in preformed biofilms, performing higher efficiency compared with other treatments (CSNPs, CS-N). Furthermore, the three-dimensional structure of L. monocytogenes biofilms was severely disrupted after DNase-CS-N treatment, with bacterial cells scattered on the surface. The morphology of biofilm cells was also greatly damaged with wrinkled surfaces, disrupted cell membranes, and leakage of intracellular nucleic acids and proteins. These results indicate the potential applicability of DNase-CS-N for inhibiting and eliminating L. monocytogenes biofilms on food contact surfaces.

Personalized CZA-ATM dosing against an XDR E. coli in liver transplant patients; the application of the in vitro hollow fiber system.

A patient with an extensively drug-resistant (XDR) New Delhi metallo-β-lactamase (NDM) and oxacillinase (OXA-48) producing Escherichia coli (E. coli) infection was awaiting orthotopic liver transplant. There is no standardized antibiotic prophylaxis regimen; however, in line with the Infectious Diseases Society of America guidance, an antibiotic prophylactic regimen of ceftazidime-avibactam 2.5g TDS with aztreonam 2g three times a day (TDS) IV was proposed. The hollow fiber system (HFS) was applied to inform the individualized pharmacodynamic outcome likelihood prior to prophylaxis. A 4-log reduction in CFU/mL in the first 10 h of the regimen exposure was observed; however, the killing dynamics were slow and six 8-hourly infusions were required to reduce bacterial cells to below the limit of quantification. Thus, the HFS supported the use of the regimen for infection clearance; however, it highlighted the need for several infusions. Standard local practice is to administer prophylaxis antibiotics at induction of orthotopic liver transplantation (OLT); however, the HFS provided data to rationalize earlier dosing. Therefore, the patient was dosed at 24 h prior to their OLT induction and subsequently discharged 8 days after surgery. The HFS provides a dynamic culture solution for informing individualized medicine by testing antibiotic combinations and exposures against the bacterial isolates cultured from the patient's infection. .

Investigation of the impact of cold plasma pretreatments, long term storage and drying on physicochemical properties, bioactive contents and microbial quality of 'Keitt' mango

There is heightened demand for dried mango fruits with desired nutritional and physicochemical qualities, microbiologically stable and chemical residue free. This has led to the exploration of innovative preservation technologies for the extension of storability prior to processing. This study investigated the impact of cold plasma (CP) treatment on physicochemical properties and microbial stability in fresh and dried 'Keitt' mango during long term storage. Freshly harvested 'Keitt' mangoes were subjected to: CP treatment (for 5 min (CP5) and 10 min, CP10), dipping in “Chronos Prochloraz” for 30 s (industry practice), and untreated group (control). All samples were stored at 11°C for 30 days, prior to minimal processing and hot air drying at 60°C. Results after 30 days of storage demonstrated that untreated samples (control) had the highest TSS (15.06 ± 0.32 °Brix), while CP10 pretreated samples had the lowest TSS (13.80 ± 0.06 °Brix) value (p ≤ 0.05). In comparison to the fresh samples post storage, all pretreated dried mango slices retained lower total flavanols with CP5 (13.49 ± 1.64 mg GAE 100/g), CP10 (20.12 ± 1.42 mg GAE 100/g) and SMB (23.89 ± 3.35 mg GAE 100/g), but higher than the dried untreated samples (6.68 ± 0.53 mg GAE 100/g). Yellowness (b*) of the fresh pulp (38.53 ± 1.73) increased significantly (p ≤ 0.05) with the long-term storage (39.88 – 46.74) and drying (55.01 – 64.90). CP pre-treatment combined with drying resulted in ≥ 2 Log reduction in microbial count. This study shows the potential of cold plasma as a pretreatment for extending storability and maintaining the quality of 'Keitt' mangoes.

Evaluation of the bactericidal activity of plasma-activated NaCl solution (PAN) against foodborne pathogens: Inactivation mechanism and application to mackerel

The objective of this study was to assess the bactericidal effect of plasma-activated NaCl solution (PAN) against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes and apply PAN as a brine salting solution for mackerel. To enhance the bactericidal effect of plasma-activated water (PAW), NaCl solutions (0, 3.5, 7, and 10 %) were treated with plasma for 20 and 40 min to generate PAN. Plasma-activated glycerol solution (PAG) was also included to evaluate the influence of water activity on plasma activation and its effect on microbial activity. Physicochemical analysis revealed that elevating the NaCl concentration of PAN led to a decrease in pH, an increase in oxidation–reduction potential, and higher levels of reactive species such as H2O2 and HOCl. PAN showed greater antibacterial activity compared to PAW and PAG, except for L. monocytogenes, where 40 min activation time and treatment time exceeding 20 min was required for significantly higher reduction to occur. PAN exhibited greater antibacterial activity at higher NaCl concentrations, which was attributed to increased ionic strength and reactive chlorine species. Additionally, we evaluated the microbial mechanisms of PAN by assessing cellular damage and alterations. The common observation across the three pathogens was that PAN resulted in increased cell membrane damage, reduced intermembrane enzyme activity, higher intracellular ROS levels, and changes in zeta potential values, while DNA damage was observed only in PAN-treated L. monocytogenes. Furthermore, when PAW and PAN were stored for up to four weeks, PAN showed higher efficacy compared to PAW. 10 % PAN was also effective against foodborne pathogens on mackerel, achieving log reductions of 3.62 for E. coli O157:H7, 4.62 for S. Typhimurium, and 3.18 for L. monocytogenes after a 20 min treatment without adversely affecting quality. Our results demonstrated the antibacterial activity and action mechanism of PAN, presenting its potential application in the seafood industry.

Synergistic antimicrobial effects of ammonium persulfate, ultrasound, and mild heat on Staphylococcus aureus under varied conditions

This study elucidated the antimicrobial effect of ammonium persulfate (PS), ultrasound (US), and 40–60 °C mild heat on Staphylococcus aureus ATCC 27213 under various growth conditions, including non-adaptation, pH-adaptation, and aridity-adaptation, in buffered peptone water (BPW) and on orange peel surfaces. For non-adapted, pH-adapted, and aridity-adapted S. aureus, the combined treatment of PS, US, and mild heat showed a synergistic effect, with log reductions of 2.05, 6.44, and 1.11 log CFU/mL in BPW after 6 min, respectively. Mechanistic experiments showed that pH-adapted S. aureus had increased SOD activity due to oxidative stress from the acidic environment, but the introduction of PS further elevated this stress, leading to greater cell death primarily through membrane damage, as confirmed by TEM, with leakage of nucleic acids and proteins. This technique was applied to an orange peel washing system, effectively inactivating aridity-adapted S. aureus, resulting in 3.51 log CFU/cm2 and 3.20 log CFU/mL reductions on orange peel and in BPW washing water, respectively, after a 6-min treatment, without any quality changes, including color and texture attributes. The enhanced inactivation on orange peel may be attributed to the presence of compounds such as ascorbic acid and limonene, which further activate persulfate and exhibit antimicrobial properties, thereby contributing to the increased efficacy of the treatment. The combined PS, US, and mild heat treatment provides an effective strategy for controlling resilient bacterial strains in the food industry, enhancing food safety through oxidative stress and mild thermal effects.

Application of sodium hypochlorite for human norovirus and hepatitis A virus inactivation in groundwater.

In this study, the effect of sodium hypochlorite (10-200 ppm of Cl2) on the inactivation of human norovirus (HuNV) GII.4 and hepatitis A virus (HAV) in groundwater was investigated using propidium monoazide (PMA)/reverse transcription quantitative real-time PCR (RT-qPCR). Initially, 4.00 log10 genome copies/μL of HuNV GII.4 or 5.50 log10 genome copies/μL of HAV were artificially inoculated in groundwater. The titers of HuNV GII.4 and HAV decreased significantly (P < 0.05) with increasing Cl2 concentrations. Groundwater was treated with 10, 30, 50, 100, 150, and 200 ppm of Cl2, and the viable HuNV GII.4 was significantly (P < 0.05) reduced to 3.28 (0.21-log reduction), 3.18 (0.31-log reduction), 3.01 (0.48 log reduction), 2.75 (0.74 log reduction), 2.54 (0.95 log reduction), and 2.34 (1.15 log reduction) log10 genome copies/μL, respectively. The viable HAV was also significantly (P < 0.05) reduced to 4.99 (0.23 log reduction), 4.76 (0.46 log reduction), 4.55 (0.67 log reduction), 4.21 (1.01-log reduction), 3.89 (1.33 log reduction), and 3.64 (1.58 log reduction) log10 genome copies/μL, respectively. The decimal reduction times (D values) (1-log10 genome reduction) of HuNV GII.4 and HAV infectivity in groundwater were predicted as 116.7 and 98.9 ppm of Cl2, respectively, using the first-order kinetics model (HuNV GII.4: y = -0.0054x + 3.3585, correlation coefficient (R2) = 0.97; HAV: y = -0.0091x + 5.0470, R2 = 0.97). The result specifically suggests that 150- to 200-ppm Cl2 can potentially be used for the inactivation of >1-log10 genome copy/μL HuNV GII.4 and HAV in groundwater.IMPORTANCEGroundwater represents a vital component of the global water supply, serving as a crucial source of potable water for humans. It serves as a source of potable water for up to 50% of the global population and accounts for 43% of all water used for irrigation. It thus follows that the sustainable management of groundwater represents a pivotal solution. However, the regrowth of pathogens in water that is not treated with chlorine or where proper residual chlorine is not maintained represents a risk to public health.

Targeted isolation of extracellular vesicles from cell culture supernatant using immuno-affinity chromatography

Extracellular vesicles (EVs) have emerged as promising therapeutics with broad clinical applications as diagnostic biomarkers and therapeutic drug delivery systems. Yet, these biopharmaceuticals pose a challenge in terms of manufacturing due to their complexity and heterogeneity. Despite advancements in the field, current purification technologies lack scalability and/or selectivity. Affinity chromatography (AC) − coupling unmatched specificity and scalability − could be used to simplify purification processing and generate clinical-grade EVs with higher titers and purity.In the present work, we report the implementation of an immuno-AC resin to capture and purify EVs directly from clarified cellular feedstocks. Firstly, to guide and support marker selection, vesicle phenotype characterization was conducted using single particle interferometric reflectance image sensing (SP-IRIS) coupled with immunofluorescence. CD81 was the marker which shown to be more present and more likely to have the other markers (CD63 and CD9). Thus, anti-CD81 VHH ligand was generated and evaluated towards recombinant CD81 protein and CD81 bearing EV particles using surface plasmon resonance (SPR). Different chromatographic studies with Anti-CD81 ligand immobilized onto agarose beads resin were conducted to optimize the process parameters (residence time, dynamic binding capacity and impurity clearance). At residence time of 2 min, on average 40 % of pure triple tetraspanin-positive EV fraction was recovered. The enrichment in EV particles herein obtained, based on scale-up calculations, it would be possible to produce 1 × 1013 EVs from a 1L cell culture, while meeting impurity requirements in a single-step purification process (impurity removal over 2 log reduction value). A single-step purification process is possible, enabling the successful isolation of homogeneous EVs population, counting with a final HCP titer of 60 ng/mL and 9 ng/mL of dsDNA impurities. EV’s morphological integrity and internalization ability were also demonstrated, showcasing elution’s efficiency under mild conditions.Overall, this work contributes to the development of a novel, highly specific, AC technology using a camelid-derived affinity ligand which, bridging the scalability requirements demanded of large-scale production, could potentiate the advent of EV-based therapies.

Ozonation combined to BAC filtration for secondary effluent treatment containing moderate concentration of heavy metals

The treatment of industrial and urban effluents is a recognized strategy for environmental preservation, which brings benefits not only to fauna and flora but also to human health. In this paper, the combination effect of ozonation (O3) and biological activated carbon (BAC) filtration treatments on the inorganic contaminants removal, disinfection, and mitigation of toxicity in secondary effluent from wastewater treatment plants (WWTP) were evaluated. Disinfection efficiency was evaluated using total coliforms and Escherichia coli inactivation, and toxicity was investigated by Eruca sativa germination, Artemia salina larvae and Daphnia similis. The O3-BAC system was efficient to remove metals, disinfect the samples and reduce toxicity. The combined treatment reduced 99.9 % of the assessed metal concentration and ≥ 96 % on samples enriched with 2x the concentration allowed by Brazilian legislation. O3-BAC also demonstrated superior bactericidal performance compared to BAC and O3 alone, exhibiting a 5-log reduction within 24 h against total coliforms and 4-log reduction in E. coli, whereas BAC and O3 achieved ≤ 3-log inactivation. Regarding toxicity, the bioassays demonstrated that the combined treatment effect improved the relative germination of E. sativa (∼97 %), and the relative root elongation showed no differences compared to the control group (∼100 %). Similar behavior was also observed in the analysis with wheat and radish seeds, with no differences noted between the treated samples and the positive control. In relation to A. salina, no toxic results were observed even at high metals concentration. Additionally, BAC treatment reduced D. similis immobilization from 97 ± 6 % to a level with no observed effect. The observed synergy suggests that the O3-BAC combination may address a variety of pollutants and improve treatment efficacy.

Distinct impacts of each anti-anti-sigma factor ortholog of the chlamydial Rsb partner switching mechanism on development in Chlamydia trachomatis.

Partner switching mechanisms (PSMs) are signal transduction systems comprised of a sensor phosphatase (RsbU), an anti-sigma factor (RsbW, kinase), an anti-anti-sigma factor (RsbV, the RsbW substrate), and a target sigma factor. Chlamydia spp. are obligate intracellular bacterial pathogens of animals that undergo a developmental cycle transitioning between the infectious elementary body (EB) and replicative reticulate body (RB) within a host cell-derived vacuole (inclusion). Secondary differentiation events (RB to EB) are transcriptionally regulated, in part, by the housekeeping sigma factor (σ66) and two late-gene sigma factors (σ54 and σ28). Prior research supports that the PSM in Chlamydia trachomatis regulates availability of σ66. Pan-genome analysis revealed that PSM components are conserved across the phylum Chlamydiota, with Chlamydia spp. possessing an atypical arrangement of two anti-anti-sigma factors, RsbV1 and RsbV2. Bioinformatic analyses support RsbV2 as the homolog to the pan-genome-conserved RsbV with RsbV1 as an outlier. This, combined with in vitro data, indicates that RsbV1 and RsbV2 are structurally and biochemically distinct. Reduced levels or overexpression of RsbV1/RsbV2 did not significantly impact C. trachomatis growth or development. In contrast, overexpression of a non-phosphorylatable RsbV2 S55A mutant, but not overexpression of an RsbV1 S56A mutant, resulted in a 3 log reduction in infectious EB production without reduction in genomic DNA (total bacteria) or inclusion size, suggesting a block in secondary differentiation. The block was corroborated by reduced production of σ54/28-regulated late proteins and via transmission electron microscopy.IMPORTANCEChlamydia trachomatis is the leading cause of reportable bacterial sexually transmitted infections (STIs) and causes the eye infection trachoma, a neglected tropical disease. Broad-spectrum antibiotics used for treatment can lead to microbiome dysbiosis and increased antibiotic resistance development in other bacteria, and treatment failure for chlamydial STIs is a recognized clinical problem. Here, we show that disruption of a partner switching mechanism (PSM) significantly reduces infectious progeny production via blockage of reticulate body to elementary body differentiation. We also reveal a novel PSM expansion largely restricted to the species infecting animals, suggesting a role in pathogen evolution. Collectively, our results highlight the chlamydial PSM as a key regulator of development that could be a potential target for novel therapeutics.

Antimicrobial, anti-biofouling, antioxidant, and biocompatible fabrics with high durability via green growth of trimetallic nanoparticles

There is a high demand for green and sustainable multifunctional fabrics, which find application in a variety of real-life contexts. This study addresses the development of antimicrobial, antioxidant, anti-biofouling and biocompatible fabrics through a one-step, versatile and cost-effective in-situ green growth strategy. Monometallic, bimetallic and trimetallic nanoparticles comprising silver (Ag), copper (Cu) and zinc (Zn) were grown in-situ on fabric surfaces using Sideritis scardica extract. The average size of nanoparticles was 99 ± 25 nm, 131 ± 29 nm, 68 ± 18 nm for Ag, Cu and Zn. The metallic nanoparticles grown on the fabric surface imparted a range of colors to the fabrics, including yellow, brownish and greenish hues. Nanoparticle-decorated fabrics have antimicrobial, antioxidant, anti-biofouling, biocompatibility, and high durability properties. The decoration of fabrics with metallic nanoparticles mediated antimicrobial properties against bacteria (E. coli and S. aureus) and fungi (C. albicans), achieving a reduction of over 99.99 % (Logarithmic reduction>4). Bimetallic and trimetallic Ag and Cu nanoparticles exhibited enhanced antifungal activity in comparison to their monometallic counterparts. The cytotoxic effects of Cu were effectively eliminated through the fabrication of bimetallic nanostructures containing Zn. Notably, the biocompatibility of monometallic and bimetallic combinations involving Ag and Zn exceeded 95 %. The water contact angles of the decorated fabrics ranged from 145° to 153°. The superhydrophobic character of the fabrics prevented pathogen adhesion and inhibited biofilm formation. Moreover, all nanoparticle-decorated fabrics demonstrated antioxidant properties, with radical-scavenging activity ranging from 46 % to 91 %. The fabrics retained their antimicrobial properties against mechanical abrasion, heating and repeated cycles of washing and bending.

Novel Antibacterial Resin Coating for Dental Provisional Crowns to Suppress Biofilms and Inhibit Secondary Caries

Provisional crowns are often used in dentistry for prolonged periods, but bacterial attachment and dental plaque often lead to gingival inflammation and secondary caries. The aims of this research were to develop a novel resin-based antibacterial provisional crown coating to prevent secondary caries and investigate the physical properties and antibacterial efficacy. The resin-based coating was prepared by addition of triethylene glycoldivinylbenzyl ether and urethane dimethacrylate, with the antibacterial monomer dimethylaminododecyl methacrylate (DMADDM) incorporated at different mass fractions. Surface characteristics including surface roughness and contact angle were assessed. The antibacterial effects were evaluated by 48 h biofilms of Streptococcus mutans (S. mutans) on provisional crowns coated with the resin-based coating. No statistically significant difference was observed in surface roughness across all groups (p &gt; 0.05), showing that adding DMADDM did not have a negative impact on surface roughness. The contact angle results revealed a significant difference in hydrophilicity between different concentrations of DMADDM (p &lt; 0.01), but overall hydrophilicity did not negatively affect the performance of the coating. The incorporation of 5% DMADDM demonstrated a significant antibiofilm effect on S. mutans biofilm CFU with a 4-log reduction compared to controls (p &lt; 0.01). Significant reductions of 4–5 folds were observed in biofilm metabolic activity and lactic acid production (p &lt; 0.01). The findings suggest that the novel coating material could enhance the long-term performance and clinical outcomes of provisional crowns, contributing to better patient oral health.

Chlorine dioxide is a broad-spectrum disinfectant against Shiga toxin-producing Escherichia coli and Listeria monocytogenes in agricultural water

Agricultural water is commonly treated with chlorine-based disinfectants, which are impacted by water quality. Understanding how water quality influences disinfectants such as chlorine dioxide (ClO2) against pathogenic bacteria is important for creating efficacious sanitation regimens. In this study, the minimum inhibitory concentration (MIC) of ClO2 needed to achieve a 3-Log reduction against Shiga toxin-producing Escherichia coli (STEC) and Listeria monocytogenes was compared across agricultural water samples. Sterile ddH2O served as a control to compare with environmental samples from Salinas Valley, CA, and laboratory standards. To test different dosages and water qualities, stock ClO2 was diluted in 24-well plates with target concentrations of 10, 5, 2.5, and 1.25 mg/L. Well plates were inoculated with pathogens and treated with sanitizer for 5 min. Following treatment, surviving pathogens were enumerated using viable cell counts. The results demonstrate that groundwater samples had the highest water quality of the environmental samples and required the lowest concentration of disinfectant to achieve 3-Log reduction against both bacteria, with MIC between 1.4 and 2.0 mg/L. Open-source samples had lower water quality and required a higher concentration of ClO2 for 3-Log reduction, with MIC between 2.8 and 5.8 mg/L for both pathogens. There was no correlation between pH, turbidity, or conductivity/TDS and reduction for either STEC or L. monocytogenes, suggesting no individual water metric was driving reduction. A lower dosage was required to achieve 3-Log reduction against STEC, while L. monocytogenes required greater concentrations to achieve the same level of reduction. Overall, these results help guide growers in using ClO2 as a broad-spectrum disinfectant and demonstrate its efficacy in reaching 3-Log reduction across agricultural water samples.

Probiotic Mixtures Consisting of Representatives of Bacteroidetes and Selenomonadales Increase Resistance of Newly Hatched Chicks to Salmonella Enteritidis Infection

There are extensive differences in the caecal microbiota of chicks from hatcheries and those inoculated with faecal material from adult hens. Besides differences in microbial composition, the latter chickens are highly resistant to Salmonella Enteritidis challenges, while the former are susceptible. In this study, we tested whether strains from genera Bacteroides, Megamonas, or Megasphaera can increase chicken resistance to Salmonella and Campylobacter jejuni when defined microbial mixtures consisting of these bacterial genera are administered. Mixtures consisting of different species and strains from the above-mentioned genera efficiently colonised the chicken caecum and increased chicken resistance to Salmonella by a factor of 50. The tested mixtures were even more effective in protecting chickens from Salmonella in a seeder model of infection (3–5 log reduction). The tested mixtures partially protected chickens from C. jejuni infection, though the effect was lower than that against Salmonella. The obtained data represent a first step for the development of a new type of probiotics for poultry.

Effect of surface charge on mechano-bactericidal activity of cellulose nanocrystals constructed chevaux-de-frise and meat preservation

The nanostructured insect wings have inspired the development of antimicrobial surfaces with mechano-bactericidal activity. For the first time, a chevaux-de-frise-like nanostructure was fabricated through the coating of cellulose nanocrystals (CNC) onto regenerated cellulose (RC) films via vacuum filtration and the impact of contact time, temperature, and surface topography on eliminating foodborne bacteria was examined. Herein, our focus is to explore in more detail how the surface charge of CNC affects the mechano-bactericidal activity and the performance of chevaux-de-frise-like nanostructure in meat preservation. CNC with neutral (weak), negative, and positive charges were prepared by hydrochloric acid hydrolysis (HCNC), TEMPO oxidation (TCNC), and amination (ACNC), respectively, and showed similar reinforcing effects on the tensile strength (increased from 74.23 ± 1.20 to about 100 MPa) and water vapor barrier property (reduced from 1.83 ± 0.08 to about 1.20 × 10−7 g m−1 h−1 Pa−1). Among them, RC-ACNC showed the highest log reduction against Escherichia coli (0.83 ± 0.06) and Staphylococcus aureus (0.69 ± 0.04) after 5 min contact, respectively, indicating the important role of attractive force in fast eliminating bacteria upon contact. It was worth noting that, during the meat preservation test, all three CNC-coated RC films exhibited a similar 0.4 log reduction of bacteria after day 4, likely due to the same physical attachment with an extended contact time. Therefore, the construction of chevaux-de-frise nanostructure from CNC on food packaging provides a sustainable strategy to contribute to preventing bacterial growth.

Inactivation of Escherichia coli O157:H7 in tomato juice by combined treatment of ethanolic clove extract and mild heat

The combination of plant extracts with mild heat treatment is a promising strategy for obtaining microbiologically and chemically safe food products. In this study, we evaluated the antimicrobial activity of ethanolic clove extract against Escherichia coli O157: H7 in nutrient broth, buffer, and tomato juice. Clove extract at 0.4% concentration showed significant E. coli O157: H7 population reduction in all media tested. E. coli O157: H7 was most sensitive to the ethanolic clove extract in nutrient-deficient media but demonstrated relative resistance in nutrient-rich media and tomato juice. Moreover, we evaluated the potential of clove extract as a preservative in tomato juice stored at cold storage temperatures of 4 °C and 15 °C. The clove extract exhibited stronger inhibitory effects against the pathogen in tomato juice stored at 15 °C than at 4 °C. Additionally, we assessed the antimicrobial efficacy of clove extract in combination with mild heat treatment against E. coli O157: H7 in tomato juice. The combined treatment of 0.05% clove extract with mild heat at 60 °C for 30 min achieved a 5-log reduction in the E. coli population in tomato juice. Our findings present a potential hurdle technology against E. coli O157: H7 in tomato juice processing by employing a combination of naturally sourced antimicrobial agents from clove and mild heat treatment. This approach can be effectively adopted by large-scale industries and small-scale local juice vendors to ensure the safety of tomato juice products.