Intermittent low-dose far-UVC irradiation inhibits growth of common mold below threshold limit value.

Mold infestations in buildings pose significant challenges to human health, affecting both private residences and hospitals. While molds commonly trigger asthma and allergies in the immunocompetent, they can cause life-threatening diseases in the immunocompromised. Currently, there is an unmet need for new strategies to reduce or prevent mold infestations. Far-UVC technology can inactivate microorganisms while remaining safe for humans. This study investigates the inhibitory efficacy of far-UVC light at 222 nm on the growth of common mold-producing fungi, specifically Penicillium candidum, when delivered in low-dose on-off duty cycles, a configuration consistent with its use in real-world settings. The inhibitory effect of the low-dose duty cycles was assessed on growth induced by i) an adjacent spore-producing P. candidum donor and ii) P. candidum spores seeded directly onto agar plates. In both setups, the far-UVC light significantly inhibited both vertical and horizontal growth of P. candidum, even when the UV doses were below the Threshold Value Limit of 23 mJ/cm2. These results suggest that far-UVC light holds the potential to improve indoor air quality by reducing or preventing mold growth, also when people are present.

Effectiveness of UV-C radiation in inactivation of microorganisms on materials with different surface structures.

INTRODUCTION AND OBJECTIVE: Ultraviolet light in the UV-C band is known as germicidal radiation and was widely used for both sterilization of the equipment and creation of a sterile environment. The aim of the study is to assess the effectiveness of inactivation of microorganisms deposited on surfaces with various textures by UV-C radiation disinfection devices. MATERIAL AND METHODS: Five microorganisms (3 bacteria, virus, and fungus) deposited on metal, plastic, and glass surfaces with smooth and rough textures were irradiated with UV-C light emitted by low-pressure mercury lamp and ultraviolet emitting diodes (LEDs), from a distance of 0.5 m, 1 m, and 1.5 m to check their survivability after 20-minute exposure. RESULTS AND CONCLUSIONS: Both tested UV-C sources were effective in inactivation of microorganisms; however, LED emitter was more efficient in this respect than the mercury lamp. The survival rate of microorganisms depended on the UV-C dose, conditioned by the distance from UV-C source being the highest at 0.5 m and the lowest at 1.5 m. For the tested microorganisms, the highest survival rate after UV-C irradiation was usually visible on glass and plastic surfaces. This observation should be considered in all environments where the type of material (from which the elements of technical equipment are manufactured and may be contaminated by specific activities) is important for maintaining the proper level of hygiene and avoiding the unwanted and uncontrolled spread of microbiological pollution.

The effects of a novel, continuous disinfectant technology on methicillin-resistant Staphylococcus aureus (MRSA), fungi, and aerobic bacteria in 2 separate intensive care units in 2 different states: An experimental design with observed impact on health care associated infections (HAIs).

BACKGROUND: Hospitals are exposed to abundant contamination sources with limited remediation strategies. Without new countermeasures or treatments, the risk of health care-associated infections will remain high. This study explored the impact of advanced photohydrolysis continuous disinfection technology on hospital environmental bioburden. METHODS: Two acute care intensive care units in different locations (ie, Kentucky, Louisiana) during different time periods were sampled every 4 weeks for 4 months for colony-forming units (CFUs) of methicillin-resistant Staphylococcus aureus (MRSA) and fungi on surfaces and floors and fungi and aerobic bacteria in the air. RESULTS: At both sites, surface testing showed greater than 98% reduction in mean fungi and MRSA CFUs. Floor results had reductions by more than 96% for fungi and MRSA at both sites. Aerobic bacterial air and fungal CFUs had reductions up to 72% and 89%, respectively. HAIs declined 70% when postactivation data were compared to preactivation data. DISCUSSION: The continuous nature of advanced photohydrolysis decontamination, its ability to be used in occupied rooms, and its independence of human resources provide an innovative intervention for complex health care environments. CONCLUSIONS: This study is on the pioneering edge of demonstrating that continuous decontamination can reduce surface, floor, and air contamination and thereby reduce the acquisition of HAIs.

Molecular Docking, DFT Calculations, Effect of High Energetic Ionizing Radiation, and Biological Evaluation of Some Novel Metal (II) Heteroleptic Complexes Bearing the Thiosemicarbazone Ligand.

New Pb(II), Mn(II), Hg(II), and Zn(II) complexes, derived from 4-(4-chlorophenyl)-1-(2-(phenylamino)acetyl)thiosemicarbazone, were synthesized. The compounds with general formulas, [Pb(H2L)2(OAc)2]ETOH.H2O, [Mn(H2L)(HL)]Cl, [Hg2(H2L)(OH)SO4], and [Zn(H2L)(HL)]Cl, were characterized by physicochemical and theoretical studies. X-ray diffraction studies showed a decrease in the crystalline size of compounds that were exposed to gamma irradiation (γ-irradiation). Thermal studies of the synthesized complexes showed thermal stability of the Mn(II) and Pb(II) complexes after γ-irradiation compared to those before γ-irradiation, while no changes in the Zn(II) and Hg(II) complexes were observed. The optimized geometric structures of the ligand and metal complexes are discussed regarding density functional theory calculations (DFT). The antimicrobial activities of the ligand and metal complexes against several bacterial and fungal stains were screened before and after irradiation. The Hg(II) complex has shown excellent antibacterial activity before and after γ-irradiation. In vitro cytotoxicity screening of the ligand and the Mn(II) and Zn(II) complexes before and after γ-irradiation disclosed that both the ligand and Mn(II) complex exhibited higher activity against human liver (Hep-G2) than Zn(II). Molecular docking was performed on the active site of MK-2 and showed good results.

Pest and disease management by red light.

Light is essential for plant life. It provides a source of energy through photosynthesis and regulates plant growth and development and other cellular processes, such as by controlling the endogenous circadian clock. Light intensity, quality, duration and timing are all important determinants of plant responses, especially to biotic stress. Red light can positively influence plant defence mechanisms against different pathogens, but the molecular mechanism behind this phenomenon is not fully understood. Therefore, we reviewed the impact of red light on plant biotic stress responses against viruses, bacteria, fungi and nematodes, with a focus on the physiological effects of red light treatment and hormonal crosstalk under biotic stress in plants. We found evidence suggesting that exposing plants to red light increases levels of salicylic acid (SA) and induces SA signalling mediating the production of reactive oxygen species, with substantial differences between species and plant organs. Such changes in SA levels could be vital for plants to survive infections. Therefore, the application of red light provides a multidimensional aspect to developing innovative and environmentally friendly approaches to plant and crop disease management.

Effect of the oscillating magnetic field on airborne fungal.

This study shows that some species of fungi are affected by the magnetic field, which should be taken into account in studies of airborne fungal and air quality. The aim of this paper was to evaluate the effect of the oscillating magnetic field (OMF) on the behavior of colonies of three fungi genus growth in different culture mediums. The stains were: Aspergillus niger, Cladosporium cladosporioides and Penicillium citrinum and were inoculated in 90 mm Petri dishes with: Malt Extract Agar (MEA), Sabouraud Dextrose Agar (SDA) and Czapek-Dox Agar (CDA). Was applied them OMF of 60 Hz/220 V between 1 and 5 mT during 2 h and then they were incubated 7 days to 28 °C. Colonies size (mm) every day was measured. Stimulation in the colonies size of all experimental conditions was showed; the greatest size of A. niger in MEA was notorious. It was demonstrated by statist analyze that only colonies size with 1 mT was significance respect to the control. The effect of OMF on the cellular metabolism was evidenced, as well as: less exudation and major pigmentation of P. citrinum in MEA; variation of pigmentation of A. niger and C. cladosporioides in CDA and increase of conidiogenesis of A. niger in SDA. Was concluded that the applied OMF had a major influence on size colony and mycelia pigmentation of A. niger that C. cladosporioides and P. citrinum, independently of the nutritional state according to the culture medium employed in this study.

Application of batch system ultraviolet light on the surface of kashar cheese, a kind of pasta-filata cheese: effects on mould inactivation, lipid oxidation, colour, hardness and sensory properties.

This research paper addresses the hypothesis that the application of ultraviolet (UV) light before packaging of pasta-filata cheese has the potential to eliminate or control post-processing contamination whilst maintaining chemical and sensorial quality. The surfaces of kashar cheese were treated at different doses of UV light (0.32-9.63 kJ/m2) in a batch UV cabinet system to determine effects on physicochemical and sensorial quality as well as mould inactivation. Untreated cheese samples were also used for comparison. Kashar cheese was naturally contaminated in a mouldy environment to provide the desired mould numbers before UV treatments. Log reductions of 0.34, 0.69 and 2.49 were achieved in samples treated at doses of 0.32, 0.96 and 1.93 kJ/m2, respectively and the mould count of sample treated at 9.63 kJ/m2 was below the detection limit. We found no significant differences in composition and hardness values between any of the treated or control cheeses. Although some individual colour values increased as the UV doses increased, this change was not observed visually in sensory analysis. Increased light intensity accelerated the lipid oxidation causing a perception of off-flavour. The results of this study show that it is necessary to examine the relationship between the oxidative and sensory interactions while determining the effective doses applied to cheese surface for microbial inactivation.

An insight into curcumin-based photosensitization as a promising and green food preservation technology.

Consumer awareness on the side effects of chemical preservatives has increased the demand for natural preservation technologies. An efficient and sustainable alternative to current conventional preservation techniques should guarantee food safety and retain its quality with minimal side effects. Photosensitization, utilizing light and a natural photosensitizer, has been postulated as a viable and green alternative to the current conventional preservation techniques. The potential of curcumin as a natural photosensitizer is reviewed in this paper as a practical guide to develop a safe and effective decontamination tool for industrial use. The fundamentals of the photosensitization mechanism are discussed, with the main emphasis on the natural photosensitizer, curcumin, and its application to inactivate microorganisms as well as to enhance the shelf life of foods. Photosensitization has shown promising results in inactivating a wide spectrum of microorganisms with no reported microbial resistance due to its particular lethal mode of targeting nucleic acids. Curcumin as a natural photosensitizer has recently been investigated and demonstrated efficacy in decontamination and delaying spoilage. Moreover, studies have shown the beneficial impact of an appropriate encapsulation technique to enhance the cellular uptake of photosensitizers, and therefore, the phototoxicity. Further studies relating to improved delivery of natural photosensitizers with inherent poor solubility should be conducted. Also, detailed studies on various food products are warranted to better understand the impact of encapsulation on curcumin photophysical properties, photo-driven release mechanism, and nutritional and organoleptic properties of treated foods.

Air bio-contamination control in hospital environment by UV-C rays and HEPA filters in HVAC systems.

The contamination of air-handling units is a widespread phenomenon in buildings with air-conditioning systems, including hospitals. The germicide capacity of UV-C rays is known and, in the air-conditioning apparatuses, the UV-C lamps are generally located inside the air ducts. Aim of the paper is to evaluate the effectiveness of UV-C lamps when they are differently placed, i.e. in a position to directly irradiate the HEPA filters surface. We built ad hoc experimental air-conditioning systems, with HEPA filters and UV-C lamps in the two described positions. The results obtained demonstrate that, for disinfection purpose, the direct irradiation of the HEPA filters by UV-C provides better results than irradiation of the air stream and the effectiveness increases when lowering the relative humidity of the air. The survival curves of the tested microorganisms (fungi) show typical tail shaped curves (two steps survival curves). Additional tests using both HEPA filters alone, and HEPA filters plus UV lamps, have been performed measuring the air pressure drop between entrance and exit the HEPA filters and collecting air samples in order to obtain total microbial and fungal count. The results obtained suggest that, at least in experimental conditions described, the radiation on filter surface reduces significantly the microbial load and the pressure drop through the filter, compared to a situation of not-irradiated HEPA filters.

In Vitro Efficacy of Chlorhexidine and a riboflavin/UVA Combination on Fungal Agents of Keratitis.

Purpose: Mycotic keratitis is a global ophthalmological problem because it is difficult to diagnose and treat. The aim of the current study was to evaluate the efficiency of using antifungal agents amphotericin B (AMB), voriconazole (VRC), 0.02% chlorhexidine (CHX), and a combination of riboflavin and UVA treatment against two fungal genera (Aspergillus and Fusarium) responsible for keratitis.Methods: We evaluated antifungal efficiencies of riboflavin/UVA and the antifungal drugs VRC, AMB, and CHX (alone and in combination) against fungal inocula at four concentrations. We recorded colony counts of isolates for Aspergillus terreus, A. flavus, A. fumigatus, Fusarium falciforme, F. proliferatum, and F. solani on Mueller-Hinton agar plates.Results: Fungal suspensions exposed to the following treatment combinations did not allow fungal growth: riboflavin/UVA and VRC, riboflavin/UVA and AMB, riboflavin/UVA and CHX, and CHX alone. We observed a statistically significant reduction (P < .05) in the number of colonies on agar plates when fungal suspensions were treated with riboflavin/UVA, VRC, and AMB only.Conclusions: Riboflavin/UVA treatment in combination with AMB, VRC, and CHX are capable of killing keratitis-inducing fungi (P < .05). The antiseptic CHX exerted a considerable antifungal effect on all strains we examined. Therefore, we recommend CHX as additional therapy against mycotic keratitis, particularly when keratitis is caused by multi-resistant members of Fusarium.

Artificial light at night alter the impact of arsenic on microbial decomposers and leaf litter decomposition in streams.

Artificial light at night (ALAN, also known as light pollution) has been proved to be a contributor to environmental change and a biodiversity threat worldwide, yet little is known about its potential interaction with different metal pollutants, such as arsenic (As), one of the largest threats to aquatic ecosystems. To narrow this gap, an indoor microcosm study was performed using an ALAN simulation device to examine whether ALAN exposure altered the impact of arsenic on plant litter decomposition and its associated fungi. Results revealed that microbial decomposers involved in the conversion of As(III) to As(V), and ALAN exposure enhanced this effect; ALAN or arsenic only exposure altered fungal community composition and the correlations between fungi species, as well as stimulated or inhibited litter decomposition, respectively. The negative effects of arsenic on the decomposition of Pterocarya stenoptera leaf litter was alleviated by ALAN resulting in the enhanced photodegradation of leaf litter lignin and microbiological oxidation of As(III) to As(V), the increased microbial biomass and CBH activity, as well as the enhanced correlations between CBH and litter decomposition rate. Overall, results expand our understanding of ALAN on environment and highlight the contribution of ALAN to the toxicity of arsenic in aquatic ecosystems.

Assessment of endoscope cleaning and disinfection efficacy, and the impact of endoscope storage on the microbiological safety level.

AIMS: The aim of the study was microbiological evaluation of the efficacy of cleaning and disinfection of endoscopes carried out with the use of endoscope washer-disinfector EndoCleaner and evaluation of the endoscope storage cabinet providing a controlled environment. METHODS AND RESULTS: The efficacy evaluation of endoscope cleaning and disinfection using the endoscope washer-disinfector EndoClener (AORT) was carried out in accordance with the PN-EN ISO 15883 standard, and the validity of endoscope storage cabinet (TRIBO LLC) was evaluated in accordance with the PN-EN 16442 standard. The micro-organism tested used in the study were as follows: Pseudomonas aeruginosa ATCC® 15442™, Enterococcus faecium ATCC® 12952™, Clostridium sporogenes ATCC® 19404™ (spores), Candida albicans ATCC® 90028™ and Aspergillus brasiliensis DSM® 1988™ (surrogate for Asperigllus niger ATCC® 16404™). It was demonstrated that the endoscope reprocessing carried out in the washer-disinfector EndoCleaner guaranteed the elimination of the micro-organism tested, and the tested endoscope storage cabinet met the microbiological criteria defined by the Polish standard PN-EN 16442 in the scope of tests. CONCLUSION: The obtained results showed that usage of washer-disinfector EndoCleaner and endoscope storage cabinet ensures the microbiological safety of using endoscopes. SIGNIFICANCE AND IMPACT OF STUDY: The increase in the frequency of procedures applying endoscopes contributes to the increased risk of transmission of potentially pathogenic micro-organisms remaining after insufficient cleaning and disinfection of these devices. Research allows assessing the effectiveness of antimicrobial cleaning and disinfection of endoscopes and the safety of storing this equipment in an endoscope cabinet. A particularly innovative aspect is equipping the cabinet with a module generating the phenomenon of radiant catalytic ionization, which is a unique solution on the market. This is one of the very few works involving the assessment of each stage, that is contamination, washing and disinfection, drying and storage of endoscopes.

Artificial Allomelanin Nanoparticles.

Allomelanin is a type of nitrogen-free melanin most commonly found in fungi. Its existence enhances resistance of the organisms to environmental damage and helps fungi survive harsh radiation conditions such as those found on spacecraft and inside contaminated nuclear power plants. We report the preparation and characterization of artificial allomelanin nanoparticles (AMNPs) via oxidative oligomerization of 1,8-dihydroxynaphthalene (1,8-DHN). We describe the resulting morphological and size control of AMNPs and demonstrate that they are radical scavengers. Finally, we show that AMNPs are taken up by neonatal human epidermal keratinocytes and packaged into perinuclear caps where they quench reactive oxygen species generated following UV exposure.

Chronic gamma radiation resistance in fungi correlates with resistance to chromium and elevated temperatures, but not with resistance to acute irradiation.

Exposure to chronic ionizing radiation (CIR) from nuclear power plant accidents, acts of terrorism, and space exploration poses serious threats to humans. Fungi are a group of highly radiation-resistant eukaryotes, and an understanding of fungal CIR resistance mechanisms holds the prospect of protecting humans. We compared the abilities of 95 wild-type yeast and dimorphic fungal isolates, representing diverse Ascomycota and Basidiomycota, to resist exposure to five environmentally-relevant stressors: CIR (long-duration growth under 36 Gy/h) and acute (10 kGy/h) ionizing radiation (IR), heavy metals (chromium, mercury), elevated temperature (up to 50 °C), and low pH (2.3). To quantify associations between resistances to CIR and these other stressors, we used correlation analysis, logistic regression with multi-model inference, and customized machine learning. The results suggest that resistance to acute IR in fungi is not strongly correlated with the ability of a given fungal isolate to grow under CIR. Instead, the strongest predictors of CIR resistance in fungi were resistance to chromium (III) and to elevated temperature. These results suggest fundamental differences between the mechanisms of resistance to chronic and acute radiation. Convergent evolution towards radioresistance among genetically distinct groups of organisms is considered here.

Diversity of thermophilic and thermotolerant fungi in corn grain.

Corn bins in the midwestern United States can reach temperatures up to 52 C. High temperatures combined with sufficient moisture and humidity in bins provide the perfect environment to promote the growth of thermophilic and thermotolerant fungi. In this article, we characterize for the first time thermophilic and thermotolerant fungi in corn grain bins using culture-based methods and pyrosequencing techniques. Corn samples were collected from local farms in western Illinois. Samples were plated and incubated at 50 C using a variety of approaches. Of several hundred kernels examined, more than 90% showed colonization. Species identified using culture methods included Thermomyces lanuginosus, Thermomyces dupontii, Aspergillus fumigatus, Thermoascus crustaceus, and Rhizomucor pusillus. Pyrosequencing was also performed directly on corn grain using fungal-specific primers to determine whether thermophilic fungi could be detected using this technique. Sequences were dominated by pathogenic fungi, and thermophiles were represented by less than 2% of the sequences despite being isolated from 90% of the grain samples using culturing techniques. The high abundance of previously undocumented viable fungi in corn could have negative implications for grain quality and pose a potential risk for workers and consumers of corn-derived products in the food industry. Members of the Sordariales were absent among thermophile isolates and were not represented in nuc rDNA internal transcribed spacer (ITS) sequences. This is in striking contrast with results obtained with other substrates such as litter, dung, and soils, where mesophilic and thermophilic members of the Sordariaceae and Chaetomiaceae are common. This absence appears to reflect an important difference between the ecology of Sordariales and other orders within the Ascomycota in terms of their ability to compete in microhabitats rich in sugars and living tissues.

Parchment processing and analysis: Ionizing radiation treatment by the REX source and multidisciplinary approach characterization.

Library material, and thus parchment, is frequently subjected to bio-deterioration processes caused by microorganisms. Fungi and bacteria cause alterations in the parchment inducing, in some cases, even the partial detachments of the surface layer and the loss of any text present on it. An important contribution to disinfection of the cultural heritage artefacts is given by the use of ionizing radiation. In this work, a preliminary study on the applicability of X-ray radiation as treatment for bio-deterioration removal is proposed. The results on the microbial growth after different irradiation treatments are shown in order to detect the dose protocol for the bio-degradation removal. Furthermore, the evaluation of the irradiation effects on the parchment microstructure is presented in order to define the applicability of the method on parchment artefacts.

Photoluminescent organisms: how to make fungi glow through biointegration with lanthanide metal-organic frameworks.

We show that filamentous fungi can emit green or red light after the accumulation of particulate lanthanide metal-organic frameworks over the cell wall. These new biohybrids present photoluminescence properties that are unaffected by the components of the cell wall. In addition, the fungal cells internalise lanthanide metal-organic framework particles, storing them into organelles, thereby making these materials promising for applications in living imaging studies.

Changes in soil taxonomic and functional diversity resulting from gamma irradiation.

Little is known of the effects of ionizing radiation exposure on soil biota. We exposed soil microcosms to weekly bursts of 60Co gamma radiation over six weeks, at three levels of exposure (0.1 kGy/hr/wk [low], 1 kGy/hr/wk [medium] and 3 kGy/hr/wk [high]). Soil DNA was extracted, and shotgun metagenomes were sequenced and characterised using MG-RAST. We hypothesized that with increasing radiation exposure there would be a decrease in both taxonomic and functional diversity. While bacterial diversity decreased, diversity of fungi and algae unexpectedly increased, perhaps because of release from competition. Despite the decrease in diversity of bacteria and of biota overall, functional gene diversity of algae, bacteria, fungi and total biota increased. Cycles of radiation exposure may increase the range of gene functional strategies viable in soil, a novel ecological example of the effects of stressors or disturbance events promoting some aspects of diversity. Moreover, repeated density-independent population crashes followed by population expansion may allow lottery effects, promoting coexistence. Radiation exposure produced large overall changes in community composition. Our study suggests several potential novel radiation-tolerant groups: in addition to Deinococcus-Thermus, which reached up to 20% relative abundance in the metagenome, the phyla Chloroflexi (bacteria), Chytridiomycota (fungi) and Nanoarcheota (archaea) may be considered as radiation-tolerant.

Biofilm characterization of Fusarium solani keratitis isolate: increased resistance to antifungals and UV light.

Fusarium solani has drawn phytopathogenic, biotechnological, and medical interest. In humans, it is associated with localized infections, such as onychomycosis and keratomycosis, as well as invasive infections in immunocompromised patients. One pathogenicity factor of filamentous fungi is biofilm formation. There is still only scarce information about the in vitro mechanism of the formation and composition of F. solani biofilm. In this work, we describe the biofilm formed by a clinical keratomycosis isolate in terms of its development, composition and susceptibility to different antifungals and ultraviolet light (UV) at different biofilm formation stages. We found five biofilm formation stages using scanning electron microscopy: adherence, germination, hyphal development, maturation, and cell detachment. Using epifluorescence microscopy with specific fluorochromes, it was elucidated that the extracellular matrix consists of carbohydrates, proteins, and extracellular DNA. Specific inhibitors for these molecules showed significant biofilm reductions. The antifungal susceptibility against natamycin, voriconazole, caspofungin, and amphotericin B was evaluated by metabolic activity and crystal violet assay, with the F. solani biofilm preformation to 24 h increased in resistance to natamycin, voriconazole, and caspofungin, while the biofilm preformation to 48 h increased in resistance to amphotericin B. The preformed biofilm at 24 h protected and reduced UV light mortality. F. solani isolate could produce a highly structured extra biofilm; its cellular matrix consists of carbohydrate polymers, proteins, and eDNA. Biofilm confers antifungal resistance and decreases its susceptibility to UV light. The fungal biofilm functions as a survival strategy against antifungals and environmental factors.