Search Results (190)

Monitoring bacterial contamination on surfaces is critical for hygiene and safety assurance in food, healthcare, and pharmaceutical settings, although routine methods still remain slow and laboratory dependent. Here, we report a portable respirometric platform based on sealed sensor sachets incorporating optical oxygen sensors to rapidly detect and quantify total aerobic viable counts (TVC) from swabbed surfaces. Following standardized surface swabbing, samples were incubated in the sachets and oxygen depletion kinetics were recorded with a handheld reader and microbial activity was inferred from oxygen consumption. Reference quantification was obtained by serial dilution and aerobic plate counting, enabling direct benchmarking of the respirometric readout against an industry-accepted culture method such as ISO 4833:2013. The platform demonstrated strong agreement with plate counts (R² > 0.94), achieving a median detection limit of 2.69 log₁₀ CFU/cm² and a dynamic range of 0–6 log₁₀ CFU/cm² for surface-associated microbial loads. The sensor system was also applied in a semi-industrial setting in a meat processing plant. Across replicate measurements, the assay provided consistent kinetic signatures and quantitative outputs, suitable for rapid and practical decision-making. Compared with traditional culture-based approaches (requiring up to 72 h), the respirometric sachets delivered actionable results within 10 h using a portable, low-infrastructure workflow, supporting rapid on-site hygiene verification and sanitation control. Full article

Marine viruses are important components of microbial communities and influence their structure and dynamics, yet their variability remains poorly documented in the northwestern Arabian Gulf. Virus-like particle (VLP) abundance was monitored over four years at three coastal sites representing different environmental settings in Kuwait. Surface and depth samples were collected during each sampling period, along with physicochemical and nutrient data. VLP abundance fluctuated throughout the study and differed among sites and between depths. VLP counts tended to be higher at the southern site and near the surface, while the lowest values were recorded in Kuwait Bay. The three sites had distinct environmental characteristics, but relationships between VLP abundance and individual physicochemical variables varied among sites and seasons. When environmental, spatial, and temporal variables were considered together, Random Forest identified season, dissolved oxygen, and nutrients, particularly nitrate, among the important predictors of VLP abundance. Dissolved oxygen showed a nonlinear association with VLP abundance in the generalized additive model (GAM), and lower abundance at depth remained significant after accounting for the measured environmental variables, while site effects were not significant in this model. Overall, VLP abundance showed marked spatial and temporal variability across Kuwait coastal waters, with patterns associated with multiple environmental and seasonal factors. This four-year record provides a baseline for viral abundance in the northwestern Arabian Gulf and supports further investigation of the biological and environmental processes influencing viral dynamics in this highly variable coastal system. Full article

This study presents the first comprehensive characterization of the airborne microbiome in a zoological garden and its comparison with the surrounding atmospheric environment. The aim of this study was to evaluate potential human health hazards associated with occupational and visitor exposure in zoo environments across 24 sampling locations. The assessment included measurements of particulate matter (PM) and gaseous pollutants, microbiological contamination of air, surfaces, settled dust, and selected items of personal protective equipment (PPE). In addition, the cytotoxic potential of settled dust samples was evaluated using A549 human lung epithelial cells. The highest concentrations of airborne PM ranged from 0.250 mg/m³ for PM₁ to 0.278 mg/m³ for PM₁₀. The concentrations of chemical contaminants varied depending on the sampling location. Airborne bacterial counts ranged from 1.1 × 10² to 3.0 × 10² colony-forming units (CFU)/m³ in employee areas and from 2.2 × 10³ to 1.5 × 10⁴ CFU/m³ in visitor areas. The average microbial contamination of surfaces in both employee and visitor areas was 4.3 CFU/cm². Amplicon sequencing revealed that the airborne microbiome was dominated by bacterial taxa belonging to Bacillota, Pseudomonadota, and Actinomycetota, as well as fungal taxa representing the phyla Ascomycota and Basidiomycota. Settled dust samples exhibited variable cytotoxicity toward A549 cells, with half-maximal inhibitory concentration (IC₅₀) values ranging from 13.1 to 53.5 mg/mL. The findings provide novel insights into the molecular composition of zoo-associated airborne microbial communities and their potential implications for environmental health risk assessment and hygiene management practices in zoological gardens. Full article

The global threat of multidrug-resistant infections requires new approaches for its management. A blend of polymethyl methacrylate (PMMA) and poly(ε-caprolactone) (PCL) electrospun nanofibrous membrane was utilised as a scaffold to sustain the release of three broad-spectrum antiseptics to combat multidrug-resistant (MDR) microorganisms. The scaffold was characterised by Fourier transform infrared spectroscopy, contact angle, and scanning electron microscopy. The latter revealed a random and smooth structure. The contact angle value of 81.8 ± 1.8 confirmed the hydrophilic nature of the scaffold, which is important for wound healing. The high surface-to-volume ratio of the scaffolds was utilised for loading benzoic acid (BA), methylparaben (MPB), and propylparaben (PPB) which were released during 72 h concentrations ranging between 0.20 and 0.8 mg mL⁻¹. The initial release of antiseptics was high and was then sustained for over 72 h. After 8 h, the burst release was 61.64 ± 4.11% for BA, 41.11 ± 2.98% for MPB and 34.32 ± 3.13% for PPB. The release profile of BA was superior to that of the MPB and PPB. The loaded scaffolds inhibited MDR-resistant methicillin-resistant Staphylococcus aureus, Escherichia coli and Candida albicans and were not cytotoxic to a fibroblast cell line. They inhibited their colonisation by the tested microorganisms to non-detectable counts or at least reduced microbial counts by at least 6–7 logs (p ≤ 0.001) for 72 h. Crystal violet techniques and electron microscopy confirmed colonisation inhibition. Because of their non-cytotoxicity and broad-spectrum antimicrobial activity, the antiseptic-loaded PMMA/PCL nanofibrous scaffolds could be utilised as wound dressings, particularly in non-healing wounds. Full article

Accurately detecting viable foodborne pathogenic bacteria is essential for food safety risk assessments and public health interventions. Traditional plate counting is time-consuming and operationally cumbersome. Immunological assays are unable to distinguish viable from dead cells, whereas conventional nucleic acid amplification is often affected by residual DNA originating from dead bacteria. These limitations render conventional approaches inadequate for rapid and precise field detection. Functional nucleic acids (FNAs) offer a promising alternative for viability detection because of their high sensitivity, specificity, target diversity, and programmable integrability. This review provides a systematic overview of molecular recognition strategies and FNA-based detection technologies for identifying viable foodborne microorganisms. We categorize the biomarkers targeted by FNAs into nucleic acids, surface structures, and metabolic activities. Building on this categorization, we examine the core principles and technological evolution of primers, aptamers, DNAzymes, guide nucleic acids, and oligonucleotide probes in viability discrimination. We then outline the practical applications of these technologies across the food supply chain and discuss the remaining challenges and future directions in the field. Ultimately, this work provides a theoretical reference and practical guidance for ensuring food safety and advancing precise microbial risk management. Full article

The increasing demand for food products and the implementation of sustainable development principles have encouraged the search for technological solutions that can reduce food losses and the environmental burden of food processing. Milk and dairy products are nutrient-rich matrices, but they also provide favourable conditions for microbial growth. Therefore, ensuring microbial safety during cheese production, ripening, and storage is essential. This study aimed to evaluate the potential application of gaseous ozone as a low-residue and potentially more sustainable approach for controlling surface microbial contamination in semi-hard cheese during ripening or storage. Ozone is characterized by low cost, strong oxidative properties, antimicrobial activity, and rapid decomposition into oxygen without leaving persistent chemical residues. Semi-hard cheese samples were treated with gaseous ozone at a concentration of 4.84 ± 0.22 parts per million (ppm) for 10, 30, 60, 90, and 150 min. After treatment, the counts of aerobic microorganisms, yeasts, and moulds were determined, and changes in moisture, fat, and protein content were assessed. After only 10 min of ozonation, aerobic microorganism counts decreased from 2826 ± 1911 × 10⁴ to 275 ± 184 × 10⁴ colony-forming units per gram (CFU/g). In contrast, a reduction in yeast counts was observed only after a longer treatment duration of 60 min. No clear treatment-dependent changes were detected in mould counts or in total fat and protein contents. Cheese moisture content decreased significantly after 10 min of ozonation and continued to decline as the ozonation duration increased. The results suggest that gaseous ozone may be used as an additional microbial control approach for semi-hard cheese during ripening or storage. However, the findings only partially confirmed a significant effect of gaseous ozone on surface microorganisms and its neutrality with respect to product proximate composition. Full article

In this exploratory pilot study, quantitative analyses were performed on seven leather wheelchairs and the protective barrier was evaluated on three leather wheelchairs, while shotgun metagenomic sequencing (Illumina and Oxford Nanopore) was conducted on pooled samples obtained from seven leather and three fabric wheelchairs to characterize microbial DNA recovered from wheelchair surfaces under routine clinical conditions. Microbial DNA and biomass were detected on all sampled surfaces, with median DNA concentrations of approximately 0.015 ng/µL, median cell counts of approximately 4.8 × 10⁵ cells/mL, and median OD600 values of approximately 0.038, although variability among wheelchairs was observed. NGS analysis revealed heterogeneous microbial communities composed mainly of taxa associated with human skin microbiota and environmental sources. Opportunistic taxa including Escherichia coli, Staphylococcus haemolyticus, Achromobacter xylosoxidans, and Clostridioides difficile DNA were detected. Differences in microbial composition were observed between the pooled fabric and leather samples, with fabric samples characterized by the dominance of specific taxa and leather samples exhibiting a more heterogeneous microbial profile. In addition, median DNA concentration, cell counts, and OD600 values were reduced by approximately 98–100% on the protective barrier compared with uncovered wheelchair surfaces, with statistically significant differences between conditions. Overall, these findings suggest that hospital wheelchairs may harbor measurable levels of microbial biomass and microbial DNA despite routine sanitation procedures. Lower contamination levels were observed on the protective barrier under the conditions tested. Due to the exploratory nature of the study, the small sample size, and the use of pooled samples for metagenomic analyses, these observations should be interpreted with caution and require confirmation in larger studies. Full article

Polyvinyl alcohol (PVA)/chitosan (CS)-based films incorporated with Antrodia cinnamomea polysaccharide (ACP) and tea tree essential oil (TTEO) were developed using a solution casting method. The physicochemical, bioactive, and structural attributes, as well as the effects of these films on post-harvest ‘Yuluxiang’ pears, were assessed. The results demonstrated strong interactions among all functional components. The integration of ACP reinforced the mechanical properties of PVA/CS-based films, whereas the combined incorporation of ACP/TTEO enhanced water resistance, ultraviolet-light shielding ability, and barrier performance against oxygen and water vapor. Contact angle measurements showed that the PVA/CS/ACP/TTEO composite film exhibited superior wettability and adhesion to pear surfaces. Furthermore, the PVA/CS/ACP/TTEO composite film exhibited potent antibacterial activity, recording 99.99% inhibition against Staphylococcus aureus and 99.91% against Escherichia coli. TGA and DTG analyses suggested that ACP improved the thermal stability and restricted the film’s degradation rate. Antioxidant assays revealed that the incorporation of ACP and TTEO markedly elevated the antioxidant ability of the PVA/CS-based film. After 21 days of storage, the PVA/CS/ACP/TTEO composite film effectively maintained firmness, titratable acidity, vitamin C levels, and the activities of superoxide dismutase and catalase in post-harvest pears. Moreover, the composite film delayed fruit yellowing and oiliness, lowered the accumulation of hydrogen peroxide and malondialdehyde, and significantly reduced microbial counts (p < 0.05). This study demonstrates that the fabricated PVA/CS/ACP/TTEO composite film possesses the ability to extend the shelf life of perishable fruits under ambient storage conditions. Full article

At the archeological site of Pompeii, the deterioration of exposed structures is frequently associated with the combined action of microbial colonization and soluble salts, both recognized as major agents of decay affecting ancient surfaces. Although biocides are commonly applied during cleaning procedures to reduce microbial biomass, their incorporation into restoration-oriented formulations for the protection of porous stone substrates requires careful assessment of efficacy, microbiological risks, and sustainability. This study evaluated the performance of 2,4,5,6-tetrachloroisophthalonitrile (chlorothalonil) and iodopropynyl butylcarbamate (IPBC) as candidate active ingredients for conservation applications in activated new mortars. Yellow tuff, gray tuff, and brick samples collected from different sectors of Pompeii were investigated through culture-based analyses, ATP quantification, and metabolic profiling. Biocidal treatments were subsequently tested under laboratory conditions. The investigated substrates exhibited variable microbial counts and metabolic activity, generally reflecting different degrees of deterioration. Chlorothalonil showed negligible inhibitory effects, whereas IPBC reduced fungal growth in a dose-dependent manner. However, the highest IPBC concentration induced a red chromatic alteration associated with the selection of a bacterial strain preliminarily identified as Micrococcus roseus. Phenotype microarray analyses revealed broad chemical tolerance. Overall, biocidal treatments may alter microbial communities, favor tolerant microorganisms, and produce undesirable aesthetic effects. Finally, the study also assessed the environmental impact associated with laboratory and field activities, highlighting potential mitigation strategies to support more sustainable conservation research practices. Full article

UV-C light is a promising non-thermal technology for microbial inactivation on food surfaces; however, its efficacy may be compromised by the spatial structure of microbial colonies. The present work investigated the influence of Listeria monocytogenes colony size on UV-C treatment effectiveness using agar-based model systems. Petri dishes were inoculated at defined concentrations and incubated to generate colonies of varying sizes, which were subsequently exposed to a UV-C dose of 0.12 J/cm². Colony growth was monitored over 48 h using an image-based analysis workflow implemented in MATLAB, combined with individual colony tracking. A neural network model was developed to predict the probability of growth cessation based on colony diameter, and quantitative PCR combined with bead-beating was used to estimate cell counts per colony. UV-C treatment applied immediately after inoculation achieved high inactivation efficacy, consistent with minimal cell aggregation. As colony size increased, treatment effectiveness declined markedly. Bootstrap analysis of the neural-network predictions identified a minimum mean growth cessation probability at a colony diameter of approximately 0.862 mm. At this diameter, the predicted probability was 56.8%, with a pointwise 95% bootstrap interval of 50.3–62.8%, corresponding to approximately ${10}^{6.14}$ (viable + non-viable) cells per colony. These findings demonstrate that colony spatial structure substantially limits UV-C efficacy and underscore the importance of early-stage intervention in food surface UV-C decontamination protocols. Full article

Spoilage in vacuum-packaged chicken breast is driven by coupled microbial succession and physicochemical changes that cannot be adequately described by a single indicator. In this study, MALDI-TOF MS-based species-level identification of culturable isolates was integrated with microbiological counts (total viable count, lactic acid bacteria, yeasts and molds, and Enterobacteriaceae), physicochemical parameters (pH, water activity, CIE $L^{\ast }{a}^{\ast }{b}^{\ast }$, and total volatile basic nitrogen (TVB-N)), and sensory evaluation of odor, appearance/color, surface texture/slime and overall acceptability (trained panel, $n=8$) during 15 days of storage at 4 °C. Associations among variables were assessed using Spearman correlation analysis. MALDI-TOF MS identified 625 isolates belonging to 67 species across 19 families. The microbial community shifted from an initially diverse flora toward late-stage dominance by Latilactobacillus sakei, L. curvatus, Hafnia alvei, Serratia spp., Carnobacterium maltaromaticum and Brochothrix thermosphacta, while Candida zeylanoides persisted throughout storage. TVC exceeded 7 log CFU/g, and TVB-N increased from 10.65 to 23.20 mg N/100 g ($p<0.05$). TVB-N showed strong positive correlations with all microbial groups ($r_s\ge 0.90$, $p<0.01$) and with seven microbial families at the family level. Hafniaceae dominance coincided with a transient mid-storage decrease in pH, consistent with the deaminative activity of H. alvei. $b_{in}^{\ast }$ showed significant associations with four microbial families and with both microbial counts and TVB-N, supporting its value as a practical spoilage indicator. Sensory evaluation identified Day 13 as the rejection point, corresponding to TVC of 6.79 log CFU/g and TVB-N of 20.80 mg N/100 g, with simultaneous deterioration of odor and appearance, in contrast to the sequential pattern typically reported under aerobic conditions. To our knowledge, this is the first study to integrate time-resolved MALDI-TOF MS-based family-level profiling with physicochemical and sensory monitoring in vacuum-packaged chicken breast stored at 4 °C, offering a condition-specific framework for shelf-life assessment. Full article

Background/Objectives: Methods of smoking have evolved over the years, including heated tobacco products. The impact of exposure to traditional tobacco smoke and heated/electronic tobacco products (IQOS) on biofilm formation has not been previously compared in vitro. Aims and objectives: The present study aimed to evaluate the impact of tobacco and electronic smoking on microbial biofilm formation on dental hard tissues. Materials and Methods: Thirty premolars were randomly assigned to six groups (n = 10 per group) according to tissue type and smoking exposure: Six experimental groups were defined: Group 1, non-exposed enamel; Group 2, enamel subjected to conventional cigarette smoke (CS); Group 3, enamel subjected to heated tobacco (HT); Group 4, non-exposed cementum; Group 5, cementum subjected to conventional cigarette smoke; and Group 6, cementum exposed to heated tobacco. Enamel and root discs were then immersed in 2 mL of an adjusted, standardized bacterial suspension of Streptococcus mutans (S. mutans) to allow bacterial biofilm adhesion after incubation for 48 h at 37 °C. The mean colony-forming unit (CFU) count was calculated, and the surface topography and roughness were assessed using scanning electron microscopy and ImageJ software with the SurfCharJ plugin, respectively. Results: Conventional cigarette smoking showed significantly higher S. mutans adhesion on the enamel and root discs compared with IQOS and control groups. Both IQOS and cigarette smoking increased roughness on enamel and root versus the control group, and cigarette smoking produced significantly higher roughness on the enamel surface when compared to IQOS; however, there were no significant differences in the roughness between the two smoking methods on the root surface. SEM analysis showed the most extensive enamel and root microtopography change in IQOS smoking. Conclusions: Aerosols from heated tobacco products (IQOS) alter the surface topography and roughness of enamel and root, while traditional cigarette smoking significantly increases bacterial colonization. Further in vivo studies are warranted to simulate the dynamic nature of the oral cavity. Full article

Background/Objectives: Catheter-associated urinary tract infections (CAUTIs) are one of the most common healthcare-related morbidities. Also, severe clinical outcomes derived from CAUTIs demand an urgent need for the development of novel antimicrobial catheter materials. Since CAUTIs are primarily driven by a wide range of microorganisms causing biofilm formation on the surfaces of catheters, evaluating the effectiveness of innovative antimicrobial materials against a broad spectrum of known uropathogens is warranted. We aim (1) to demonstrate the ability of incorporated organo-selenium versus that of an FDA-cleared antimicrobial catheter and (2) to show that the results of the study are consistent against the most common microorganisms causing urinary tract infections in humans. Methods: Based on encouraging preliminary studies, three percent of organo-selenium (weight-based), as a novel antimicrobial catheter material, was incorporated into thermoplastic polyurethane (TPU). This was compared in vitro with plain polyurethane catheters and the SILQ ClearTract catheter with a zwitterionic coating (FDA-cleared for its antimicrobial properties in December 2022). The antimicrobial activity was studied against Candida albicans, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, MRSA, and Staphylococcus epidermidis by assessment of colony-forming unit counts along with visual confirmation using Scanning Electron Microscopy (SEM). Results: Plain polyurethane catheters (control group) showed 7- to 8-log of in vitro growth for all tested microbes, whereas the antimicrobial zwitterionic SILQ ClearTract catheters still showed 6- to 7-log of microbial growth. In contrast, organo-selenium-incorporated catheters demonstrated no detectable in vitro growth for all tested microbes (C. albicans, E. coli, K. pneumoniae, P. mirabilis, P. aeruginosa, S. aureus, MRSA, and S. epidermidis). SEM analysis also validated the findings. Conclusions: Potentially non-leaching organo-selenium, as a novel urinary catheter material, significantly inhibited microbial attachment, growth, and biofilm formation across a wide spectrum of common uropathogenic organisms compared to a zwitterionic catheter, providing a strong foundation for further detailed in vivo and clinical studies. Full article

Coastal land reclamation is widely implemented to support coastal development, yet its effects on microbial indicators in coupled surface water–groundwater systems remain poorly understood. This study examined the spatiotemporal variability of four microbial indicators and their environmental associations using 46 months of monthly monitoring (April 2016–January 2020) in eastern Guanghai Bay, China. Total bacterial counts, fecal coliforms, Escherichia coli, and total coliforms were analyzed using multivariate statistical methods. Surface water exhibited elevated levels of fecal indicators, with consistently higher pollution levels in the Xiaoma River than in the Dama River and clear seasonal variation associated with climatic and hydrological conditions. Groundwater showed pronounced spatial heterogeneity: Wells 1 and 2 exhibited relatively elevated microbial contamination, whereas Well 3 maintained persistently low microbial levels under high-salinity and high-alkalinity conditions. These patterns suggest that reclamation may be associated with groundwater microbial distribution through changes in groundwater transport pathways and hydrochemical conditions, while anthropogenic pressures also played an important role in shaping contamination patterns. These findings offer practical insights for groundwater protection and sustainable management in reclaimed coastal environments. Full article

Plasma-pulse water treatment using a high-voltage underwater spark discharge is a reagent-free approach with potential for simultaneous disinfection and physicochemical modification of water. In this study, a laboratory-scale recirculating reactor (Vtot = 10 L) equipped with a storage capacitor of C = 0.25 μF was operated at U = 15–30 kV and a pulse repetition frequency of about 1.8 Hz to evaluate disinfection performance and system-level energy characteristics for two water matrices, surface wastewater and tap water. The corresponding calculated capacitor-stored energy ranged from 28.1 to 112.5 J per pulse. Microbiological and physicochemical measurements were performed in triplicate. At U = 30 kV, the total microbial count in wastewater decreased from approximately 1 × 10⁵ CFU/mL to below the method detection limit (LOD = 1 CFU/mL) within 2–3 min. For the 2 min/10 L operating mode, the system-level specific energy input was estimated at 6.7 kWh/m³. During the initial treatment period, temperature-compensated conductivity (σ25) decreased by 3–8%, depending on the water matrix, and then increased with prolonged treatment. These results show that the tested reactor can provide rapid reagent-free reduction in culturable microflora under the studied conditions. However, plasma-pulse treatment should be regarded primarily as an advanced treatment, polishing, or pre-treatment option for complex water matrices rather than as a universal replacement for conventional large-volume disinfection technologies. Full article