Search Results (134)

Air purification is a key process aimed at removing harmful impurities and providing a safe and comfortable environment for human life and work. This study presents the results of an investigation into the composition, textural, and sorption properties of a multichannel carbon filtering material developed for air purification from biological (infectious) contaminants. The filtering block has a cylindrical shape and is manufactured by extrusion of a plastic composition based on carbonized rice husk with the addition of binding agents, followed by staged thermal treatment (calcination, activation, and demineralization). The filter’s effectiveness is based on the inactivation of pathogenic microorganisms as the air passes through the porous surface of the sorbent, which is modified with broad-spectrum antiseptic agents (active against bacteria, bacilli, fungi, and protozoa). X-ray diffraction analysis revealed the presence of amorphous carbon in a tubostratic structure, with a predominance of sp- and sp²-hybridized carbon atoms not incorporated into regular graphene lattices. IR spectroscopy demonstrated the presence of reactive functional groups characteristic of the developed porous structure of the material, which is capable of selective sorption of antiseptic molecules. SEM surface analysis revealed an amorphous texture with a loose structure and elements in the form of spherical semi-ring formations formed by overlapping carbon plates. An experimental setup was also developed using cylindrical multichannel carbon blocks with a diameter of 48 mm, a length of 120 mm, and 100–120 longitudinal channels with a cross-section of 1 mm². The obtained results confirm the potential of the proposed material for use in air purification and disinfection systems under conditions of elevated biological risk. Full article

The therapeutic use of silver nanoparticles (AgNPs) has been increasing, especially in phototherapy strategies. The plasmonic properties of AgNPs have contributed to their excellent results as phototherapeutic agents, namely for photodynamic therapy (PDT), photothermal therapy (PTT), and photodynamic inactivation of microorganisms. Moreover, the capacity of these nanostructures to release silver ions (Ag⁺) and enhance the production of reactive oxygen species (ROS) has been explored in combination with light to treat several diseases. Moreover, synthesis, functionalization, and conjugation strategies with targeting agents have been widely studied to optimize selectivity and maximize the therapeutic efficacy of these nanoplatforms. In this work, we reviewed the recent advancements (2019–2024) in the use of AgNPs for phototherapy applications, with an emphasis on evaluating therapeutic efficacy and specific targeting. According to the literature, in oncology, AgNPs have been predominately employed in PTT-based strategies, demonstrating significant tumor cell death and preservation of healthy tissues, in both in vitro and in vivo studies. Concurrently, AgNP-mediated PDT has emerged as a promising approach for the eradication of bacteria and fungi, particularly those commonly associated with antibiotic resistance. The compiled data indicate that AgNPs represent an innovative and effective therapeutic alternative, with a strong potential for clinical translation, in both cancer treatment and the management of hard-to-treat infections. Full article

Hepatocellular carcinoma (HCC) imposes a significant burden on global public health. Exposure to aflatoxins, potent mycotoxins produced by Aspergillus fungi contaminating staple foods, and chronic hepatitis B virus (HBV) infection are major etiological factors, especially where they co-exist. This review examines the critical role of the p53 tumor suppressor pathway as a primary target and convergence point for the carcinogenic actions of aflatoxins and HBV. Aflatoxin B₁ (AFB₁), a Group 1 carcinogen, exerts significant genotoxicity, characteristically inducing a specific hotspot mutation (R249S) in the TP53 gene via DNA adduct formation, thereby compromising p53’s critical tumor suppressor functions. This R249S mutation is considered a molecular fingerprint of aflatoxin exposure. Concurrently, the HBV X protein (HBx) functionally inactivates wild-type p53 through direct binding and by promoting its degradation. The synergistic disruption of the p53 pathway, driven by AFB₁-induced mutation and amplified by HBV-mediated functional inhibition, significantly enhances the risk of HCC development. This review addresses how aflatoxin exposure alters key aspects of p53 and how this damage interacts with HBV-mediated p53 suppression, providing crucial insights into hepatocarcinogenesis. The knowledge synthesized here underscores the importance of mitigating aflatoxin exposure alongside HBV control for effective HCC prevention and treatment strategies. Full article

Leucaena leucocephala (Lam.) de Wit is listed in the world’s 100 worst alien invasive species because of the risks it poses to native plant communities. Life history traits, such as high growth and reproductive rates, and a high capacity to adapt to different environmental conditions may contribute to its invasive properties. Biotic stressors, such as herbivores, pathogens, and competing plant species are known to exert significant selective pressure on the plant’s survival, distribution, and abundance. L. leucocephala has been reported to contain several compounds involved in the defense functions against these biotic stressors. A large amount of L-mimosine, a non-protein amino acid, was found in all plant parts of L. leucocephala, including its flowers. L-Mimosine is toxic to herbivorous mammals and insects, parasitic nematodes, pathogenic fungi, and neighboring competing plant species by inactivating various essential enzymes and blocking DNA replication, and/or inducing oxidative stress conditions. Several flavonoids, polyphenolic compounds, and/or derivatives of benzoic and cinnamic acids are toxic to parasitic nematodes, pathogenic fungi and bacteria, and competing plant species by disrupting plasma membrane structures and functions, and various metabolic processes. These compounds may represent the invasive traits of L. leucocephala that have undergone natural selection during the evolution of the species. They may contribute to the defense functions against the biotic stressors, and increase its survival, distribution, and abundance in the introduced ranges. This is the first review to focus on the compounds involved in the defense functions against biotic stressors. Full article

Treating poultry manure with calcium compounds is the primary technique for inactivating toxic pathogens such as bacteria, fungi, or viruses and decreasing the risk of biological contaminant release into the environment. On the other hand, the preferable method for reducing its volume is incineration with the aim of obtaining highly concentrated fertilizer. This paper presents the optimization of the biological deactivation of fresh poultry manure using calcium hydroxide via central composite design and response surface methodology. The results revealed that the optimum parameters required to decrease the number of E. coli bacteria to below the acceptable level (1000 CFU/g) were 5.0 wt% Ca(OH)₂ at 22 °C and an exposure time of 209 h. A regression analysis showed a good fit of the approximated parameters to the experimental data (R² = 98%, R_adj.² = 97%). Additionally, laboratory tests involving ash samples obtained from the incineration of poultry manure with the addition of 5 wt% calcium hydroxide (T = 500 °C, t = 5 h) intended as a fertilizer for degraded soils were performed. The analysis revealed that the content of pure manure ash in the sample incinerated with Ca(OH)₂ was approximately 47.5%. An X-ray diffraction analysis of the ash sample revealed that the main crystalline component was calcite (67.5 wt% CaCO₃), the phases containing phosphorus were apatite (3 wt%) and hydroxyapatite (3 wt%), whereas the source of the bioavailable form of phosphorus was the amorphous phase (15.5 wt%). An analysis of the ash extracts in a 2% citric acid solution revealed that the phosphorus concentration (287 mg/L) was two times lower than that of potassium (661 mg/L). The best results of phytotoxicity tests with Sinapis alba were obtained for soils containing no more than 1.0 wt% ash with calcium hydroxide. Full article

This study aimed to investigate the effectiveness of ozonated water in the sanitation and postharvest quality of acerola fruits. The experiment comprised seven treatments: a control group with untreated fruits, three different durations of exposure to ozone microbubbles (20, 40, and 60 min), and three different durations of exposure to ozone-free microbubbles (20, 40, and 60 min). Acerola fruits were stored in a refrigerated environment below 5 °C at 87% relative humidity. Microbiological and quality analyses were performed immediately after ozonation on day 0 and then on storage days 3, 6, and 9. The quality parameters assessed included the fresh mass loss percentage, firmness, soluble solid content, pH, total titratable acidity, vitamin C, color, total phenolic compounds, and total antioxidant activity. The use of ozonated water was found to effectively maintain the firmness of the acerolas, regardless of the exposure duration. Changes were observed on the surface of fruits treated with ozone microbubbles, especially when 60 min of exposure was adopted. Treating acerolas with ozone microbubbles for 20 min proved to be the best condition for inactivating bacteria and fungi and preserving the vitamin C, pH, total titratable acidity, total phenolic compounds, and total antioxidant activity of the fruits throughout storage. In conclusion, ozonated water is a promising technology for sanitizing and preserving the postharvest quality of acerola. Full article

(1) Background: Improper disinfection of slurry and municipal wastewater poses a serious threat to public health. These fluids are reservoirs of viruses, bacteria, fungi and parasites. (2) Methods: This study aimed to evaluate, on a laboratory scale, the disinfection effectiveness of fine bubble aeration with air activated by radiant catalytic ionization (RCI) against Enterococcus faecalis, Escherichia coli, Salmonella Senftenberg W775, Listeria monocytogenes, Clostridioides difficile, Aspergillus niger and Ascaris suum eggs in comparison to conventional atmospheric air aeration. The inactivation kinetics was calculated on the basis of Weibull and first-order models. (3) Results: The final number of microorganisms on the last day in the slurry disinfected with RCI ranged from 1.14 × 10² for L. monocytogenes to 1.91 × 10⁷ CFU (colony-forming unit) × mL⁻¹ for C. difficile. After using atmospheric air aeration, the bacteria number ranged from 2.82 × 10³ for L. monocytogenes to 2.24 × 10⁷ CFU × mL⁻¹ for C. difficile. In the case of aeration using RCI technology, the maximum time required to eliminate 99.9% of the microorganisms population was 20.84 days in slurry and 16.40 days in wastewater and was determined for A. niger. In the case of atmospheric air, this time was 47.76 days in slurry and 28.74 days in wastewater and was determined for C. difficile. In turn, the time to inactivate the number of invasive A. suum eggs by 90% was 20.70 and 24.61 weeks for RCI and 21.33 and 27.82 weeks for atmospheric air, respectively. Both in the case of slurry and municipal wastewater, disinfection with RCI was more effective than aeration with atmospheric air. (4) Conclusions: Our study, for the first time, exploits the possibility of using RCI in aeration to improve the efficiency of pathogen elimination from wastewater and slurry. Full article

The Gti1/Pac2 protein family, which is highly conserved across fungi, is pivotal in processes such as fungal development, spore formation, protein export, toxin production, and virulence. Despite its importance, the precise functions of Pac2 within entomopathogenic fungi have yet to be fully understood. In our study, the MaPac2 gene from M. acridum was identified, and its functions were explored. Studying the domain of the protein showed that MaPac2 comprises 422 amino acids with a characteristic Gti1/Pac2 family domain (Pfam09729). Additionally, MaPac2 is predicted to have an N-terminal protein kinase A phosphorylation site and a potential cyclin-dependent kinase phosphorylation site, highlighting its potential regulatory roles in the fungus. Our findings indicate that the inactivation of MaPac2 resulted in faster germination of conidia and a marked reduction in conidial production. Furthermore, stress tolerance tests revealed that the absence of MaPac2 significantly bolstered the fungal resilience to UV-B radiation, heat shock, SDS exposure, and stresses induced by hyperosmotic conditions and oxidative challenges. Virulence assessments through bioassays indicated no substantial differences among the WT, MaPac2-disrupted strain, and CP strains in the topical inoculation trials. Interestingly, deletion of MaPac2 increased the fungal virulence by intrahemocoel injection. Furthermore, we found that disruption of MaPac2 impaired fungal cuticle penetration due to the diminished appressorium formation but increased the fungal growth in locust hemolymph. These findings provide further insights into the roles played by Gti1/Pac2 in insect pathogenic fungi. Full article

This experiment was designed to investigate the immobilization effect of fulvic acid-modified palygorskite on cadmium (Cd) and evaluate metabolism responses in plants in terms of chlorophyll, proline, and soluble protein and in soils in terms of microorganism number and enzymatic activity. The characteristics of the specific surface area and X-ray diffraction (XRD) spectra of modified palygorskite were analyzed to obtain information on the clay structure. The infrared (IR) spectrum characteristics of modified palygorskite and Cd adsorption products were analyzed to study the Cd immobilization mechanism. The modified palygorskite was hydrated magnesia aluminum silicate clay with a surface area of 50.923 m²/g and dominant mesopore distribution. The silanol group (Si-OH) and carboxyl (-COOH) present in modified palygorskite can form a complex with Cd to induce a 12.8–60.3% reduction in available Cd in soil and a 17.9–76.8% reduction in plant Cd. A 7.0–22.9% rise in chlorophyll, a 19.2–64.1% increase in proline, and a 20.1% maximum increase in soluble protein in plants were observed. A 1.45-fold maximal increase in number of bacteria, a 56.7% maximal rise in number of fungi, a 64.8–206.2% rise in dehydrogenase activity, and a 22.9-fold maximal increase in cellulase activity in the soil were obtained. Fulvic acid-modified palygorskite is a recommended Cd inactivator based on the fact that clay application reduces the ecological risk of Cd entering the food chain and stimulates plant physiological metabolism and soil biochemical activity. Full article

The methylotrophic yeast Komagataella kurtzmanii belongs to the group of homothallic fungi that are able to spontaneously change their mating type by inversion of chromosomal DNA in the MAT locus region. As a result, natural and genetically engineered cultures of these yeasts typically contain a mixture of sexually dimorphic cells that are prone to self-diploidisation and spore formation accompanied by genetic rearrangements. These characteristics pose a significant challenge to the development of genetically stable producers for industrial use. In the present study, we constructed heterothallic strains of K. kurtzmanii, ensuring a constant mating type by unifying the genetic sequences in the active and silent MAT loci. To obtain such strains, we performed site-directed inactivation of one of the two yeast MAT loci, replacing its sequence with a selective HIS4 gene surrounded by I-SceI meganuclease recognition sites. We then used transient expression of the SCE1 gene, encoding a recombinant I-SceI meganuclease, to induce site-specific cleavage of HIS4, followed by damage repair by homologous recombination in mutant cells. As a result, heterothallic strains designated ‘Y-727-2(alpha)’ and ‘Y-727-9(a)’, which correspond to the α and a mating type, respectively, were obtained. The strains demonstrated a loss of the ability to self-diploidize. The results of PCR and whole genome analysis confirmed the identity of the contents of the MAT loci. Analysis of the genomes of the final strains, however, revealed a fusion of chromosome 3 and chromosome 4 in strain Y-727-2(alpha)-1. This finding was subsequently confirmed by pulsed-field gel electrophoresis of yeast chromosomes. However, the ability of the Y-727-2(alpha)-derived producers to efficiently secrete recombinant β-galactosidase was unaffected by this genomic rearrangement. Full article

Aflatoxins are foodborne toxins that occur naturally in various crops because of fungal contamination, particularly from two strains, namely Aspergillus flavus and Aspergillus parasiticus. Given their adverse properties, which are teratogenic, mutagenic, and carcinogenic, aflatoxins present a significant public health concern. Consequently, efforts are underway to inactivate aflatoxins and inhibit the growth of these fungi to prevent toxin formation. Since chemical treatments for food products are undesirable or even restricted in some countries, alternative approaches are also implemented. This study investigated gamma-ray (γ-ray) irradiation as a potential method for reducing aflatoxin levels. Specifically, solutions of aflatoxins B1, B2, G1, and G2 were irradiated with doses of 1, 2, 4, and 8 kGy using a cobalt-60 irradiation source. Following γ-irradiation, a notable reduction in aflatoxin levels was observed, particularly for types B1 and G1, which process higher toxicity. This finding suggests γ-irradiation as a feasible method for aflatoxin deactivation. Additionally, as a proof of concept, almond samples spiked with aflatoxins and A. flavus were irradiated. The results showed a decrease in both aflatoxin levels and microbial load in these samples. Overall, these findings indicate that γ-irradiation is a promising approach to aflatoxin reduction, microbial decontamination, and the potential extension of almonds’ shelf life. Full article

The issue of the microbiological spoilage of bakery products with an extended shelf life declared by the producer was the reason for searching for an effective solution. The aim of the investigation was to find the sources of infection, identify microorganisms causing product spoilage, and propose ways to eliminate the problem without the use of chemical preservatives in the product. It was found that the dominant contaminating microorganisms are yeasts of the genus Hyphopichia sp., Saccharomyces sp., and Candida spp., as well as molds—Aspergillus spp. and Penicillium spp. The microbiological quality of the production environment was assessed, and as a remedial action, a disinfection process was carried out. The influence of gas composition in MAP (modified atmosphere packaging) and the use of ethanol during packaging on the incidence of yeast or mold occurrence was checked. The effectiveness of using sourdough was also tested. The best results were achieved by using sourdough obtained with selected starter cultures and using a gas mixture for packaging in the proportion of 70% carbon dioxide and 30% nitrogen, without the addition of ethanol. These conditions ensured the expected shelf life of bakery products while maintaining their quality. Full article

A simulated system was created to evaluate an air circulation-type geothermal ventilation system, focusing on measuring microbial contamination levels on the surface of the heat exchange unit. Additionally, this study examined sterilization methods using UV lamps on the surface of the heat exchanger. The fungal concentration on the surface of the heat exchanger showed a tendency to increase over time. Although direct comparison is challenging due to the varying concentrations of outdoor air fungi at different measurement times, the surface fungal concentration was highest at a minimum airflow rate of 150 m³/h compared to other conditions. However, since the adhesion of contaminants from outdoor air to the surface of the heat exchanger is influenced not only by airflow but also by outdoor temperature and relative humidity conditions, future research needs to consider these factors. According to the ATP measurement results, microbial contamination was evaluated as “slightly dirty” after 24 h and “dirty” after 48 h of operating the experimental apparatus. Therefore, it is advisable to clean the internal surfaces of the geothermal ventilation system every 1–2 days. The results of the sterilization experiments using UV lamps indicated that irradiation for approximately 30 min inactivated 94.5%-to-96.1% of microorganisms derived from outdoor air. However, since the sterilization dose varies depending on the type of microorganism, it is necessary to determine the optimal irradiation time based on the target microorganisms and the UV lamp’s irradiation intensity. Full article

Low ventilation rates used to conserve energy in pig nurseries in winter can worsen air quality, harming piglet health. A recirculating air cleaner consisting of a dust filter and ultraviolet C (UVC) lamps was evaluated in a pig nursery. It had a recirculation rate of 6.4 air changes per hour, residence time of 0.43 s, and UVC volumetric dose of 150 J·m⁻³. Reduced ventilation led to high particulate matter (PM) concentrations in the nursery. During the first 9 d, the air cleaner increased floor temperature in its vicinity by 1.9 °C vs. a more distant location. The air cleaner had average removal efficiencies of 29 and 27% for PM_2.5 (PM with aerodynamic equivalent diameter or AED < 2.5 µm) and PM₁₀ (PM with AED < 10 µm), respectively. It reduced PM_2.5 and PM₁₀ concentrations by 38 and 39%, respectively, in its vicinity vs. a more distant location. The air cleaner was mostly inconsistent in inactivating heterotrophic bacteria, but it eliminated fungi. It trapped 56% of the ammonia but did not trap nitrous oxide, methane, or carbon dioxide. The air cleaner demonstrated the potential for reducing butanoic, propanoic, and pentanoic acids. Design improvements using modeling and further testing are required. Full article

Ozone is a molecule that has gained increasing interest in recent years by food industries for sanitization of food-grade surfaces. Compared to chemical sanitizers such as chlorine, hydrogen peroxide, or peracetic acid, ozone shows undeniable advantages, such as the absence of by-products that should affect human health or the possibility of generating it when needed. Therefore, the aim of this paper was the assessment of the resistance to ozonized water of two pathogenic bacteria (Listeria monocytogenes, Salmonella) and of three airborne food-spoiling fungi (Aspergillus brasiliensis, Hyphopichia burtonii, and Penicillium nordicum) inoculated on stainless steel tiles and treated in static conditions with 1 to 6 mg L⁻¹ (pathogens) or 8.5 mg L⁻¹ (filamentous fungi). Ozonized water gave different results based on the tested microorganisms: pathogenic bacteria proved markedly more sensible to ozone than filamentous fungi, even if great differences were observed at inter- and intra-specific levels for both categories of microorganisms. Nevertheless, the non-linear inactivation kinetics of the studied strains made the calculation of a punctual F-value difficult, so in industrial practice, adequate tailoring of the treatments to be applied, based on the registered extrinsic factors and the industrial bio-burden, would be appropriate. Full article