Search Results (271)

The intensification of the urban heat island effect poses a critical threat to the preservation and habitability of compact historic districts. The Alameda de Hércules in Seville exemplifies this vulnerability, where the intersection of heritage protection and extreme Mediterranean summers limits conventional climate adaptation. This study conducts a multi-temporal evaluation of the square’s climate resilience, spanning from its configuration prior to major 21st-century renovations to its current state and future projections, proposing future interventions. By integrating advanced microclimatic simulation and high-fidelity energy modeling, the research assesses a dual-function strategy: the improvement of the thermal environment while implementing non-intrusive photovoltaic pavements (PVPs) for energy generation. Environmental parameters, including air temperature, mean radiant temperature (MRT), and the universal thermal climate index (UTCI), were analyzed alongside the renewable energy potential of the site’s mobility infrastructure. Four heritage-sensitive interventions were tested: PV-integrated bicycle lanes, shading canopies, reflective pavement, and permeable paved grass. The results demonstrate that the canopies and paved grass zones can lower surface temperature up to 3.7–4.3 °C, reduce UTCI stress up to 2.3–3.0 °C, and decline MRT up to 10.6 °C. These values correspond to the maximum reductions achieved in specific zones. However, the PVP can locally increase surface temperature by about 4.7 °C and the reflective pavements increase MRT by around 10.4 °C, while generating an estimated annual energy yield of 174.19 MWh. The analysis under future climate projections suggests that these strategies remain equally effective under future scenarios. These findings confirm that PV-integrated urban surfaces offer a viable, reversible, and replicable approach to retrofitting historic public spaces, harmonizing climate-adaptive cooling with decentralized energy production without compromising the site’s cultural significance. Full article

Botrytis cinerea, the causal agent of gray mold disease, is a major phytopathogen responsible for substantial losses in horticultural crops. In this study, cultivation conditions for Bacillus velezensis R22 were optimized to maximize overall antifungal activity against B. cinerea. A Plackett–Burman design was used to identify medium components affecting antifungal activity in flask cultures, followed by response surface methodology based on a central composite design (CCD) to optimize sucrose concentration, temperature, and agitation speed in a stirred bioreactor. Maximum antifungal activity was obtained at 17.45 g/L initial sucrose, 31.8 °C, and 293 rpm. The biological relevance of the optimized culture was confirmed in a tomato infection model, in which gray mold severity was reduced by 85.3% relative to the untreated control and by 59.9% relative to the non-optimized R22 culture. The same CCD approach was subsequently applied to determine cultivation conditions that maximize the concentration of R22 viable cells. The optimal parameters for 24-h growth (35.46 g/L sucrose, 36.5 °C, and 454 rpm) differed markedly from those identified for maximal antifungal activity. When evaluated on uninfected tomato plants, cultures produced under conditions favoring higher cell density showed enhanced plant growth-promoting activity compared to the non-optimized culture. Mass spectrometric analysis of lipopeptide extracts revealed that the enhanced antifungal activity was accompanied by an increased abundance of long-chain homologs across all major lipopeptide families, particularly surfactins. Thus, our results indicate that maximizing overall antifungal activity may be of greater practical significance than optimization of the individual fungicidal agent. Full article

Aspergillosis encompasses a heterogeneous spectrum of diseases caused by filamentous fungi of the genus Aspergillus, ranging from allergic airway disorders and chronic pulmonary infection to rapidly progressive invasive disease. Aspergillus fumigatus is the predominant pathogen worldwide, although other species, including Aspergillus flavus, Aspergillus terreus and cryptic species, contribute to morbidity and may exhibit intrinsic or acquired antifungal resistance. Early and accurate laboratory diagnosis is essential for timely treatment, appropriate antifungal selection, and stewardship. Traditional culture remains foundational, enabling confirmation of viable organisms, species-level identification, and antifungal susceptibility testing, but sensitivity is limited and turnaround times are prolonged. Non-culture approaches—including galactomannan, β-D-glucan, lateral flow assays, PCR, and next-generation sequencing—enhance diagnostic sensitivity, facilitate early detection, and allow identification of resistance-associated mutations. Optimal diagnostic performance is achieved through integrated, multimodal strategies combining laboratory tests with clinical and radiological findings. In invasive disease, concurrent use of biomarkers and molecular assays improves specificity and positive predictive value, while in allergic bronchopulmonary aspergillosis, immunological markers remain central. Future directions include standardised molecular protocols, novel antigenic and host-based biomarkers, and cost-effective, risk-adapted diagnostic algorithms to refine detection, guide therapy, and improve patient outcomes. Full article

Background: A compact, in-house-developed ultraviolet germicidal irradiation (UVGI) system using eight 36 W Philips low-pressure mercury UV-C lamps with a peak emission at 253.7 nm was developed for effective sterilization of bacteria and fungi using a wireless mode of operation. Methods: Under controlled laboratory conditions, the system was tested against representative biofilm-forming microorganisms, including Bacillus subtilis, Escherichia coli K12, and a multidrug-resistant Candida albicans M-207 isolate. Microbial viability was assessed using colony-forming unit (CFU) enumeration and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, with structural changes analyzed by scanning electron microscopy (SEM). Cultures were exposed to 253.7 nm UV-C radiation at distances of 1–5 m for 15–90 min. Results: UV-C exposure resulted in time- and distance-dependent reductions in viable counts for all tested organisms, as determined by CFU analysis. At 1 m and 15 min exposure, viable counts for all tested organisms were reduced below the limit of detection (LOD) of the CFU assay, indicating substantial microbial inactivation under the tested conditions. Reduced efficacy was observed at increased distances (3 m and 5 m), with log₁₀ reductions varying depending on organism and exposure conditions. Residual metabolic activity detected by the MTT assay suggests the presence of non-proliferating or damaged cells, consistent with the different endpoints measured by the two assays. The SEM analysis further revealed disruption of biofilm architecture and reduction in cell density with increasing UV dose. Conclusions: The UVGI system demonstrated dose-dependent inactivation of biofilm-forming microorganisms under controlled conditions, supporting its proof-of-concept efficacy. Further studies are required to evaluate performance under real-world conditions. Full article

Background: Ultraviolet-C (UV-C) radiation is a high-energy physical mutagen capable of inducing DNA damage and oxidative stress, thereby generating genomic variability in photosynthetic organisms. However, its genome-wide effects in unicellular eukaryotic microalgae remain poorly characterized. This study developed a UV-C mutagenesis protocol in Chlamydomonas reinhardtii and evaluated its genomic and physiological impacts. Methods: Axenic cultures of Chlamydomonas reinhardtii (137c+) were exposed to UV-C (100–280 nm) for 12, 48, and 96 min. Viable colonies were analyzed by Random Amplification of Polymorphic DNA PCR (RAPD-PCR) to assess genetic variability, while chlorophyll content and the expression of stress-responsive genes were measured via spectrophotometry and Reverse Transcription quantitative Polymerase Chain Reaction (RT-qPCR), respectively. Results: UV-C treatment induced extensive genomic polymorphism with heterogeneous clustering patterns independent of exposure time, consistent with stochastic mutagenesis. Several mutants exhibited reduced chlorophyll content, indicating impaired photosynthetic efficiency. In contrast, one genotype (pop18) maintained wild-type chlorophyll levels despite marked genetic divergence, coupled with upregulation of antioxidant, DNA repair, and stress-response genes. Conclusions: Overall, UV-C irradiation represents an effective approach to generate non-directional genomic variability in Chlamydomonas reinhardtii, with evidence that random mutagenesis can drive functional reorganization of stress-response pathways, supporting its application in microalgal strain improvement. Full article

Salmonella persistence contributes to infection relapse, chronic carriage, and reduced antibiotic efficacy. Traditionally viewed as dormant subpopulations that passively survive antibiotic exposure, persister cells are now increasingly recognized as dynamic, heterogeneous, and context-dependent physiological states shaped by bacterial regulatory programs and host microenvironmental pressures. This review examines Salmonella persistence from a multiscale perspective. We first clarify key antibiotic survival phenotypes, including resistance, heteroresistance, tolerance, persistence, and viable but non-culturable states. We then discuss how host-derived stressors, such as phagosomal acidification, nutritional restriction, metal perturbation, and reactive oxygen and nitrogen species, promote growth-restricted, persistence-associated bacterial states. At the bacterial level, we summarize stress-response networks involving the stringent response, SOS response, toxin–antitoxin systems, and auxiliary regulators that coordinate metabolic remodeling, growth restriction, and antibiotic survival. At the host level, we highlight how organ reservoirs, immune cell subsets, metabolic cues, and Salmonella-mediated immune niche remodeling shape persistence-associated phenotypes in vivo. Finally, we discuss clinical and translational implications, including endogenous relapse, resistance evolution, and emerging anti-persistence strategies. Together, this review provides a framework for understanding Salmonella persistence as a multiscale, niche-dependent process relevant to recurrent and chronic infection. Full article

The rise in global consumption of fresh vegetables is a response to their nutrient-dense composition and low caloric content—key factors for optimising human metabolic health. This study evaluated the Quantitative Microbial Risk Assessment (QMRA) of Helicobacter pylori and enteric pathogens in fresh vegetables within the central highlands of Peru. The research integrated conventional microbiology, qPCR, and Monte Carlo simulations. The results revealed a high prevalence of Escherichia coli (83.7%), with a heterogeneous distribution where Huancayo presented the highest prevalence (95.5%) and Chupaca the lowest (68.2%). In contrast, pathogens such as H. pylori and Campylobacter jejuni showed marginal prevalences of 2.33% and 3.49%, respectively, with detections restricted to leafy and root vegetables at specific points of sale. Although biochemical tests indicated the presumptive presence of Helicobacter pylori, the qPCR results were negative, possibly due to the bacteria’s viable but non-culturable (VBNC) state. The QMRA model showed a highly skewed annual infection risk distribution, with E. coli presenting the highest risk: median Pann = 1.000 and 84.3% of simulations exceeding the WHO tolerable threshold of 10⁻⁴. For Salmonella Typhimurium and Shigella flexneri, 22.4% and 9.1% of simulations exceeded the same threshold, respectively. The results underscore the urgent need to implement traceability programs and improve agricultural practices across the evaluated provinces. Full article

Polluted mangroves are ecologically sensitive habitats that provide ecosystem services. In a selected polluted forest of Simaisma, viable aerobic, halophilic, and heterotrophic hydrocarbon-degrading bacterial strains were isolated from both rhizosphere and non-rhizosphere regions. The chemical composition of sediment showed a clear distinction between the rhizosphere and non-rhizosphere sites, as well as coastal and non-coastal sediments, as per Principal Component Analysis (PCA) clustering. Anthracene, an indicator of oil pollution, was present along with vanadium, another marker of oil pollution. Through selective enrichment cultures, a total of 25 hydrocarbon-degrading bacterial strains were isolated, including Lysinibacillus xylanilyticus, Bacillus cereus, Lysinibacillus sphaericus, Pseudomonas stutzeri, Acinetobacter calcoaceticus, and Staphylococcus warneri. To link the adaptation of bacteria to sediment chemistry, nine B. cereus strains were investigated using their MALDI-TOF MS protein profiles combined with their dendrogram. The relationship between protein profiles of B. cereus strains with their biosurfactant production capabilities was explained by a tanglogram. The tanglegram suggests that biosurfactant production is an important functional trait in B. cereus, but it is not consistently reflected in the overall protein profile. This suggests that bacterial adaptation in the polluted mangrove sediments may involve changes at multiple cellular levels, including metabolic activity and variation in protein expression profiles. These findings confirm the involvement of mangrove-associated bacteria in the sustainability of mangrove forests by promoting bioremediation of oil pollution, thereby protecting coastal ecosystems and their environmental and socio-economic aspects. Full article

Antimicrobial blue light (aBL) within the visible violet–blue spectrum has emerged as a promising non-chemical strategy for microbial control, yet its performance across environmentally realistic matrices and surfaces remains insufficiently characterised. Here, we evaluate a continuous-exposure aBL LED system operating within the visible 407–421 nm range for its antimicrobial efficacy against Escherichia coli K-12 MG1655 and Bacillus cereus NCTC 11143 across liquid cultures, agar surfaces, and representative built-environment materials (glass and steel bar). Bacterial inactivation was quantified using culture-based enumeration and flow cytometric viability profiling. The system delivered a controlled irradiance of 0.72 mW/cm² at 58 cm, corresponding to cumulative doses of 2.59–62.23 J cm⁻² over 1–24 h of exposure. Significant, time-dependent reductions in viability were observed across all matrices relative to fluorescent-light controls, with near-complete or complete loss of recoverable cells on solid surfaces following prolonged exposure. Flow cytometric analyses revealed progressive transitions from viable to injured and dead cell populations, consistent with photodynamic inactivation mediated by endogenous photosensitiser activation and reactive oxygen species generation. These findings demonstrate that continuous visible-light aBL illumination can achieve effective multisurface microbial inactivation under moderate irradiance conditions compatible with occupied environments, supporting its translational potential as a sustainable, non-chemical decontamination strategy for healthcare, food-processing, and built environments. Full article

This study investigated the bactericidal effect and examined the associated cellular damage of low temperature plasma (LTP) combined with slightly acidic electrolyzed water (SAEW) against Listeria monocytogenes. Single-factor experiments were conducted to assess the bactericidal efficacy under individual treatment conditions, followed by the evaluation of three different combination sequences. An orthogonal experimental design was performed to optimize the key parameters, and the optimal treatment conditions were determined as LTP at 45 W with an electrode spacing of 1 mm for 2 min, combined with SAEW at an available chlorine concentration (ACC) of 30 mg/L. Under these conditions, confocal laser scanning microscopy (CLSM) with SYTO 9/PI staining confirmed that the combined treatment caused cell death, as indicated by loss of membrane integrity in treated cells. A resuscitation assay further ruled out the viable but non-culturable (VBNC) state, as no bacterial growth was detected after 48 h of enrichment. The leakage of intracellular proteins and nucleic acids was measured using the Coomassie Brilliant Blue method combined with a microplate reader, and changes in cellular morphology were observed by scanning electron microscopy (SEM). The results demonstrated that SAEW+LTP treatment exerted a distinct effect, significantly disrupting bacterial cell membrane integrity, inducing the leakage of intracellular contents, and causing obvious morphological damage to the bacterial cells. In conclusion, the combined treatment of LTP and SAEW significantly improved the bactericidal efficiency against L. monocytogenes, which may be due to the combined disruptive effects on membrane integrity and subsequent structural and functional damage to the cells. Future investigations are needed to unravel the precise mechanisms, establish the efficacy against a wider panel of strains, and explore the potential for practical application in food matrices. Full article

This study systematically compared the induction and resuscitation characteristics of the viable but non-culturable (VBNC) state in Klebsiella pneumoniae FY170-1 following sublethal exposure to sodium hypochlorite (NaClO) or glutaraldehyde (GA). Treatment with 30 mg/L NaClO or 60 mg/L GA for 60 min reduced culturability to below the detection limit (<1 CFU/mL). However, CTC staining showed that 50.80% and 63.44% of cells, respectively, retained respiratory activity, while SYTO 9/PI staining indicated that membrane integrity was largely preserved, consistent with induction of the VBNC state. Scanning electron microscopy revealed distinct morphological alterations in the two groups. NaClO-induced VBNC cells showed surface depressions and wrinkling, consistent with oxidative damage, whereas GA-induced cells exhibited filamentous and net-like surface structures, consistent with aldehyde-mediated cross-linking. Among the tested additives, sodium succinate showed the strongest resuscitation-promoting effect under the experimental conditions, with OD600 increasing after approximately 2 h of incubation. Post-resuscitation analysis further revealed marked differences between the two VBNC states. In resuscitated NaClO-induced VBNC cells, ATP partially recovered, but reactive oxygen species remained elevated and catalase activity showed little recovery. In contrast, resuscitated GA-induced VBNC cells exhibited lower ATP recovery but more rapid normalization of ROS and better recovery of oxidative stress-related parameters. Total protein analysis and SDS-PAGE further supported distinct patterns of protein-level alteration between the two treatments. Overall, these findings suggest that NaClO and GA induce phenotypically distinct VBNC states in K. pneumoniae, with different recovery behaviors and stress response profiles. Sodium succinate was identified as the most effective recovery-promoting additive under the tested conditions. These results highlight the risk of underestimating bacterial survival when culturability is used as the sole indicator of disinfection efficacy and support the need for more comprehensive viability assessment. Full article

With the continuous expansion of Pleurotus ostreatus cultivation, substantial quantities of post-harvest spent mushroom substrate (SMS) are generated. Improper disposal of this organic waste poses potential threats to soil health, including contamination and ecological imbalance. Consequently, a rigorous safety assessment is indispensable to support the sustainable and agronomically viable utilization of SMS as a soil amendment. In this study, P. ostreatus SMS was subjected to sterilized and non-sterilized treatments, and a controlled co-culture system integrating P. ostreatus mycelium with wheat was established. This system facilitated a comprehensive evaluation of residual mycelium impacts on wheat growth and development at phenotypic, cytological, and non-targeted metabolomics (LC-MS) levels. Results demonstrated that direct field application of non-sterilized SMS severely compromised wheat performance, inducing root necrosis and significantly reducing grain set. Comparative experiments confirmed that non-sterilized SMS—not its sterilized counterpart—exerted pronounced phytotoxic effects, markedly inhibiting seedling growth and triggering wilting symptoms. To elucidate the temporal dynamics of mycelial interaction, wheat seedlings were inoculated with viable P. ostreatus mycelium and co-cultured for seven days. Under these conditions, the mean root length of the control group (10.82 cm) was approximately threefold that of the treatment group. Histopathological analysis revealed a progressive infection pattern initiating at the root apex and extending basipetally; prolonged exposure ultimately caused complete root system collapse. Scanning electron microscopy further showed extensive mycelial colonization on infected root surfaces, accompanied by characteristic cellular damage—including severe cell wall wrinkling and widespread cell death. LC-MS profiling identified 1867 annotated compounds. Comparative analysis revealed significant dysregulation of secondary metabolism, with 495 metabolites upregulated and 419 metabolites downregulated in the treatment group. Collectively, these findings provide robust evidence that unprocessed P. ostreatus SMS poses tangible agronomic risks upon direct soil application. This study establishes a critical scientific foundation for developing safe, evidence-based protocols for the valorization and integrated management of SMS. Full article

Cow’s milk allergy (CMA) remains one of the most common food allergies in infancy, requiring the avoidance of cow’s milk and its derivatives. Breast milk is the best source of nutrition for infants. For those infants with CMA whose mothers are unable to breastfeed or choose not to, extensively hydrolysed formulas (eHFs) are widely recommended as first-line milk substitutes, whereas hydrolysed rice formulas (HRFs) are increasingly recognised as a viable alternative. This concept paper provides a healthcare professional (HCP) perspective on HRF, drawing on expert consensus from two meetings convened in 2025. Discussions noted the long history of safe and effective HRF use in Europe, its nutritional adequacy, and the evolving international guidelines supporting HRF as an alternative first-line option. A key meeting outcome was the development of a practical decision tree to help UK clinicians decide when HRF should be the preferred choice. Key considerations for its use in non-breastfed infants include the following: parental/caregiver stress related to persistent symptoms; ongoing symptoms despite multiple interventions; cultural and lifestyle choices; religious dietary requirements; and specialists’ recommendations. Secondary considerations highlighted by HCPs include the following: proven reactions whilst infants are breast-milk-fed together with parental request for formula; faltering growth; multiple symptoms; taste acceptance (older infants); and parental preference based on experience. The role of functional components, such as prebiotics and human milk oligosaccharides (HMOs), was noted in regard to the emerging evidence of benefits to the microbiome and immune development. The experts emphasised the importance of engaging HCPs across all levels of CMA care and addressing challenges in translating current guidance into treatment practice. It was concluded that, overall, HRF represents a nutritionally complete, plant-based alternative that has been shown to be well tolerated (taste, symptoms) in clinical studies. It can be used to broaden therapeutic options for infants with CMA in the UK who are not exclusively fed breast milk. Full article

Aeromonas hydrophila is a major seafood-borne pathogen capable of persisting under preservative-associated stress by entering a viable but non-culturable (VBNC) state, thereby evading culture-based detection. Here, untargeted metabolomics was applied as the primary analytical approach to elucidate metabolic reprogramming during VBNC formation under seafood-relevant preservation conditions. Cells were incubated at 4 °C for 30 days in sodium benzoate-supplemented saline, comparing 0.85% NaCl (culturable condition) and 4% NaCl (VBNC-inducing condition), with sampling every 6 days. Under 4% NaCl with sodium benzoate, culturability declined from 6.18 log CFU/mL at day 0 to undetectable levels by day 30, while cell viability was retained, confirming VBNC induction. UHPLC–ESI–QTOF–MS profiling detected over 893 intracellular metabolic features, of which 518 metabolites were significantly altered between VBNC and culturable states at day 30. Principal component analysis revealed clear, time-dependent metabolic divergence, with the VBNC trajectory explaining 34.4% (PC1) and 11.5% (PC2) of total variance. Pathway enrichment analysis demonstrated significant remodeling of alanine, aspartate and glutamate metabolism (8/28 hits, FDR = 5.7 × 10⁻⁴); arginine biosynthesis (5/14 hits, FDR = 5.44 × 10⁻³); purine metabolism (10/70 hits, FDR = 8.34 × 10⁻³); and pyrimidine metabolism (7/39 hits, FDR = 1.35 × 10⁻²), indicating nitrogen conservation and metabolic downshifting. A robust biomarker panel, including depleted cyclic AMP, aminoadipic acid, hypotaurine, O6-CM-dG, and betaine, and enriched urocanic acid, pipecolic acid, proline, azelaic acid, and orcinol perfectly discriminated VBNC from culturable cells. These findings demonstrate that sodium benzoate-based preservation can induce a metabolically reprogrammed VBNC state in A. hydrophila, highlighting a hidden food safety risk beyond culture-based assessment. Full article

Acinetobacter baumannii is a leading cause of healthcare-associated infections and is classified among the highest-priority antimicrobial-resistant pathogens. Its clinical success reflects the convergence of antimicrobial resistance (AMR) and biological traits that promote environmental persistence and transmission. Acinetobacter baumannii has undergone a remarkable transformation over the past few decades, evolving from a relatively obscure environmental bacterium into a globally recognized multidrug-resistant pathogen. Its prevalence in healthcare settings, particularly intensive care units, has made it a leading cause of ventilator-associated pneumonia, bloodstream infections, wound infections, and urinary tract infections. Beyond its antibiotic resistance, the bacterium’s ability to persist in hospital environments and adapt to host defences has amplified its clinical significance. Recent research has uncovered complex networks of virulence factors, regulatory systems, and metabolic strategies that enable A. baumannii to thrive in hostile environments and evade host immunity, providing new insights into its pathogenesis and potential therapeutic vulnerabilities. This review summarizes the main mechanisms underlying its pathogenicity, including desiccation tolerance, biofilm formation, disinfectant resistance, metal acquisition, motility, and the ability to enter viable but non-culturable states. In A. baumannii, AMR functions as a pathogenesis-adjacent trait, enhancing survival and clonal dissemination through genomic plasticity, resistance islands, efflux systems, and envelope remodeling. Key resistance pathways involve carbapenem-hydrolyzing oxacillinases, metallo-β-lactamases, permeability defects, and multidrug efflux, often coexisting within high-risk clones. From a clinical perspective, management of carbapenem-resistant strains requires accurate infection diagnosis, reliable susceptibility testing, site-specific and PK/PD-optimized therapy, and early reassessment. Overall, the success of A. baumannii reflects the integration of resistance and persistence within healthcare ecosystems, highlighting the need for coordinated strategies combining stewardship, infection control, improved diagnostics, and anti-biofilm or anti-virulence approaches. Full article