Enhanced vegetable production in hydroponic systems using decontamination of closed circulating fluid.

While plant microorganisms can promote plants by producing natural antibiotics, they can also be vectors for disease transmission. Contamination from plant management practices and the surrounding environment can adversely affect plants, leading to infections and hindered growth due to microbial competition for nutrients. The recirculation of nutrient-rich fluids can facilitate the transport of microorganisms between vegetables in the hydroponic production system. This issue can be addressed through the application of the decontamination method in the hydroponic liquid. Ultraviolet light (UV-C) has been employed for microbiology, and its effects on lettuce were evaluated in this study. This study aims to assess the effectiveness of a decontamination system using UV-C in hydroponic solutions during nutrient recirculation in hydroponics. We evaluated the time required for lettuce plants to reach their maximum height, as well as their pigment content, phenolic compounds, antioxidant capacity, and micro and macronutrient levels. The evaluation was conducted under two photoperiods (18 and 20 hours) in lettuce samples exposed to UV-C in the hydroponic fluid, with control groups not exposed to UV-C. The application of the UV-C decontamination system in hydroponic circulation water containing nutrients accelerated plant growth while maintaining nutritional values equal to or higher than those in the control groups without such a system. The results of microorganism control highlight the potential application of this technique for enhancing and expediting vegetable production. This approach reduces production time and enhances nutrient absorption and the content of certain compounds and minerals.

Antimicrobial Formulation of a Bacterial Nanocellulose/Propolis-Containing Photosensitizer for Biomedical Applications.

With the aim of contributing to the development of more efficient materials for wound care, new topical formulations based on bacterial nanocellulose (BNC) hydrogels containing propolis were produced. Characterizations confirmed the incorporation of propolis into the BNC matrix, maintaining its structure and properties. Rheological analysis confirmed that the hydrogels showed thixotropic behavior appropriate for topical application. Chromatographic profiles showed sustained release of propolis biomarkers for at least 20 h. The formulations did not present mutagenicity. For application in photodynamic inactivation (PDI), BNC/propolis hydrogels were prepared with the photosensitizers methylene blue (MB). Spectroscopy and confocal fluorescence microscopy confirmed the interaction of MB and propolis in BNC hydrogels, as well as the formation of a new composite material. In the antibacterial assays, formulations containing MB and propolis significantly reduced Staphylococcus aureus growth. In the presence of light, BNC/MB hydrogels completely inhibited the microorganism. Therefore, the results suggest potential materials for the prevention or treatment of Staphylococcus aureus infections in wounds.

Obtaining poly (lactic acid) nanofibers encapsulated with peppermint essential oil as potential packaging via solution-blow-spinning.

The development of active packaging based on biodegradable material and incorporating active compounds, such as essential oil, is a new technique to ensure food safety without harming the environment. In this study, nanofiber mats of poly (lactic acid)/ polyethylene glycol (PLA/PEG) blend incorporated with peppermint essential oil (PO) at different ratios (5-20 % v/w) were produced by solution-blow-spinning (SBS) for potential packaging application. Electron microscopy showed a cylindrical and interlaced morphology for PLA/PEG/PO and a significant increase in the diameter (139-192 nm) of the nanofibers by increasing PO content. All nanofibers showed high thermal stability (278-345 °C) suitable for use in the food industry. Nuclear magnetic resonance (13C NMR) spectrum confirmed PO in the nanofibers after SBS. ATR-FTIR spectral analysis supported the chemical composition of the nanofiber mats. PO addition led to obtaining hydrophobic nanofibers, enhancing the contact angle to 122° and decreasing water vapor permeability (60 % reduction compared to the PLA/PEG (3.0 g.mm.kPa-1.h-1.m-2). Although the PLA/PEG/20%PO nanofibers did not show halo formation in 24 h, they effectively extended the strawberries' shelf-life at 25 °C, evidencing PO release over time. It also reduced weight loss (2.5 % and 0.3 % weight loss after 5 days for PLA/PEG and PLA/PEG/20%PO, respectively) and increased firmness (8-12 N) for strawberries packed with the nanofiber mats. It is suggested that PLA/PEG films incorporating PO may be used as an active, environmentally friendly packaging material.

Physiotherapy elastic band disinfection by UV-C irradiation in an intensive care unit.

BACKGROUND: The transmission of healthcare-associated pathogens is mainly related to the massive flow of patients with infections in hospitals, presenting surfaces as potential transmission sources of these microorganisms. The physiotherapist who works in the intensive care area has become a specialist in daily routine in critical care with ventilatory support and post-surgical recovery. Furthermore, for this, the instruments are used in the patient's hands and body. Chemicals such as chlorine derivatives, triclosan, chlorhexidine and, 70 % alcohol are currently used to decontaminate surfaces. This study evaluated ultraviolet C (UV-C) irradiation efficiency in the physiotherapy object's disinfection in daily use in the Hospital Intensive Care Unit (ICU). METHODS: the microbiological quantification carried out using the elastic band during physiotherapy in a cross-sectional study with 21 patients. The methodology compared the cleaning protocol (70 % alcohol) with a new irradiation method in elastic band in the ICU. RESULTS: The results showed microbial reductions in the elastic band using both 70 % alcohol and UV-C irradiation (254 nm), with 60 s of illumination, totaling a light dose of 0.78 J/cm2; however, the UV-C irradiation showed better results. CONCLUSION: This study showed that disinfection by UV-C irradiation could be introduced in an intensive care hospital environment for physiotherapeutic conduct.

Curcumin/d-mannitol as photolarvicide: induced delay in larval development time, changes in sex ratio and reduced longevity of Aedes aegypti.

BACKGROUND: Resistant populations of Ae. aegypti have been a major problem in arboviruses epidemic areas, generating a strong demand for novel methods of vector control. In this regard, our group has demonstrated the use of curcumin as an efficient photoactive larvicide to eliminate Ae. aegypti larvae. This work was aimed to evaluate the Ae. aegypti (Rockefeller) development under sublethal conditions, using a curcumin/d-mannitol (DMC) formulation. The photolarvicidal efficacy under semi-field and field conditions (wild populations) was also analyzed, as well as the photobleaching and residual activity of DMC. RESULTS: A delay in development time when larvae were exposed to sublethal concentrations of DMC was observed, followed by significant changes in sex ratio and reduction in longevity. DMC also presented a low residual activity when compared to usual larvicides, and had a substantial photolarvicidal activity against wild populations in field trials, achieving 71.3% mortality after 48 h. CONCLUSIONS: Overall, these findings are of great biological importance for the process of enabling the implementation of DMC as a new product in the control of Ae. aegypti larvae, and contributes to the improvement of new plant-based larvicides. © 2021 Society of Chemical Industry.

Effects of ultraviolet light and curcumin-mediated photodynamic inactivation on microbiological food safety: A study in meat and fruit.

BACKGROUND: About one-third of the food produced in the world is lost or wasted every year. Contamination can cause significant food loss throughout the entire supply chain, including harvesting, processing, storage, and transport to consumers. This study evaluated ultraviolet-C (UV-C) light and curcumin-mediated photodynamic inactivation (PDI) for the decontamination of meat and fruit. METHODS: The cut pieces of food samples contaminated with E. coli or S. aureus were submitted to photonic treatments. For UV-C, samples were irradiated with UV-C lamps (254 nm) for 0, 1, 2, 3, 4, 5 and 10 min. For PDI, samples were incubated using 40 and 80 µM curcumin and irradiated with 450 nm at 5, 10, and 15 J/cm2 of light doses. The microbiological analysis was performed by counting the colony-forming unit (CFU). RESULTS: UV-C irradiation reduced the number of E. coli in beef by (1.0 ± 0.2) log10 CFU/mL after 5 min of exposure. In chicken and pork, the numbers of E. coli were reduced by (1.6 ± 0.7) log10 CFU/mL and (1.6 ± 0.4) log10 CFU/mL after 4 and 10 min of irradiation, respectively. In apple the reductions were (3.2 ± 0.4) and (3.8 ± 0.2) log10 CFU/mL after 5 and 10 min of UV-C irradiation, respectively. PDI (40 µM, 15 J/cm2) reduced the number of S. aureus by (1.5 ± 0.2), (1.4 ± 0.2) and (0.6 ± 0.4) log10 CFU/mL in beef, chicken, and pork meat samples, respectively. In apple the greatest reduction was (2.0 ± 0.4) log10 CFU/mL using 80 µM and 10 J/cm2. CONCLUSION: UV-C irradiation and PDI had an anti-microbial effect in food and our findings indicated that the greatest effect was achieved in apples. Therefore, these techniques may be useful to reduce E. coli and S. aureus contamination levels on the surface of meats and fruits, being promising for applications in the field of microbiological food safety.

Photodynamic inactivation for in vitro decontamination of Staphylococcus aureus in whole blood.

BACKGROUND: Blood can be the target of microbial cells in the human body. Erythrocytes, platelets, and plasma concentrates in blood bags used in hemotherapy for blood transfusion are contamination targets, which can trigger serious diseases in blood. These infections can cause septicemia that can lead to death if not recognized rapidly and treated adequately. The aim of this study was to evaluate the photodynamic inactivation in the in vitro decontamination of Staphylococcus aureus in whole blood, erythrocytes and platelet-rich plasma. METHODS: Photodynamic inactivation using light doses of 10, 15 and 30 J/cm2 at 630 nm and an hematoporphyrin-derivative photosensitizer (Photogem®) solutions at 25 and 50 µg/mL were evaluated. Toxicity of treatment was determined by hemolysis and cell viability assays. RESULTS: The S. aureus reduction in phosphate buffered saline (PBS), whole blood, erythrocytes and platelet-rich plasma at 15 J/cm2 and 50 µg/mL were 7.2, 1.0, 1.3 and 0.4 log CFU/mL, respectively. Quantitative and qualitative analyses were performed in whole blood samples, and Photogem® showed a low risk of hemolysis (10.7%) in whole blood. However, 100% of erythrocytes suffered hemolysis in the absence of plasma. The cell viability assay showed 13.9% of apoptosis in erythrocytes, but normal platelet viability. CONCLUSION: S. aureus inactivation of whole blood samples using 50 µg/mL Photogem® and 15 J/cm2 resulted in better outcomes, providing promising indications for treatment of bacterial contamination of blood, and in this work, alternative possibilities to apply the technique for blood decontamination are discussed.

Manual Operated Ultraviolet Surface Decontamination for Healthcare Environments.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of a new handheld equipment based on a mercury low-pressure vapor lamp. The Surface UV® device was tested in Staphylococcus aureus, Streptococcus mutans, Streptococcus pneumoniae, two strains of Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and other clinical microorganisms isolated from different surfaces of a public health hospital. BACKGROUND DATA: The incidence of hospital infections has increased in recent years. Despite the variety of available chemicals to reduce the microorganisms, the search for antimicrobial agents and the characterization of novel targets are a continued need. Also, the minimization of chemical procedures is a constant need, and the use of ultraviolet (UV) light as a germicidal device for microorganisms' inactivation has been an alternative and one possible approach for the reduction of contamination. MATERIALS AND METHODS: The in vitro decontamination was performed by application of Surface UV in different species of microorganisms (study 1). The surface decontamination was carried out by application of Surface UV on each surface of hospital environment (study 2). The device presents ultraviolet C (UV-C) light at 254 nm and produces an irradiance of 13 mW/cm2 at a distance of 1 cm of the surfaces. The light dose was 0.78 J/cm2 for 60 sec of application in both studies. RESULTS: The results for in vitro decontamination indicated a log10 reduction factor of 6.5 for S. aureus, 6.7 for S. mutans, 6.2 for S. pneumoniae, 5.4 for E. coli, 5.2 for E. coli (ATCC 8739), 5.4 for P. aeruginosa, and 6.7 for C. albicans. The hospital level of microorganisms decreases more by 75% after the procedure. CONCLUSIONS: The study highlights the development and successful application of a new portable device that can reduce the risk of contamination in health settings. Our results suggest that Surface UV is efficient and may be an alternative decontamination method.

Oral Decontamination of Orthodontic Patients Using Photodynamic Therapy Mediated by Blue-Light Irradiation and Curcumin Associated with Sodium Dodecyl Sulfate.

OBJECTIVE: The aim of this study was to investigate the effects of the antimicrobial photodynamic therapy (aPDT) using the association of curcumin with the surfactant sodium dodecyl sulfate (SDS) for oral decontamination in orthodontic patients. BACKGROUND DATA: The installation of the orthodontic appliances promotes an increase in the retentive area that is available for microbial aggregation and makes difficult the oral health promotion. However, aPDT is one possible approach that is used for the reduction of oral microbial load. MATERIALS AND METHODS: Twenty-four patients (n = 24) were randomly distributed into four groups: Light group: which was treated only with the blue light, no drug; PDT group, which was treated with curcumin and blue light; PDT + S group, which was treated with curcumin plus surfactant and irradiated with blue light; and Chlorhex group, which was treated with chlorhexidine. The photosensitizer agent was prepared by adding 0.1% of SDS to a curcumin solution of 1 g/L. Two distinct LED devices emitting blue light (450 ± 10 nm) were used as follows: extra-oral irradiation (200 mW, 80 mW/cm(2), 36 J and 14 J/cm(2)) and intra-oral irradiation (1200 mW, 472 mW/cm(2), 216 J and 85 J/cm(2)).The collection of nonstimulated saliva (n = 3; 3 mL/collection) was performed at the following steps: (1) immediately before swishing (curcumin, chlorhexidine, or water); (2) after swishing; and (3) after performing aPDT treatments. The colony-forming units (CFU) were counted visually, and the values were adjusted to CFU/mL. RESULTS: There was significant Log reduction for PDT (from 6.33 ± 0.92 to 5.78 ± 0.96, p < 0.05), PDT + S (from 5.44 ± 0.94 to 3.83 ± 0.71, p < 0.01), and Chlorhex (from 5.89 ± 0.97 to 2.55 ± 1.80, p < 0.01) groups. The survival rate was significantly reduced in both PDT + S and Chlorhex groups compared with all situations (p < 0.05). However, there was no significant difference between PDT + S and Chlorhex groups (p ≥ 0.05). CONCLUSIONS: These results indicate that when associated with the surfactant SDS, the aPDT can be used as an adjutant and a convenient agent to promote the oral decontamination in clinical practice.

Different Photoresponses of Microorganisms: From Bioinhibition to Biostimulation.

The effective treatment of antimicrobial modalities continues to be a serious challenge, mainly due to the increasing number of multidrug resistance pathogenic microorganisms. Microbial bioinhibition is an alternative method that has shown to be effective. This study investigated and described the effect of the visible light on five different microorganisms. The studied groups were composed by the species Acanthamoeba polyphaga, Candida albicans, Mycobacterium massiliense, Pseudomonas aeruginosa, and Staphylococcus aureus. These microorganisms were analyzed after six light doses exposition with three different wavelengths: 450, 520, and 630 nm. The present study indicates two different behaviors: bioinhibition and/or biostimulation. The bioinhibition effect was calculated using different percentages of the microorganism population, compared to the control group, in which the maximum value corresponds to 94% growth inhibition. The biostimulation effect was evaluated by the microorganism population increment for specific light doses. Our results showed a 132% population growth as the maximum value. These results were assessed by variance analysis. The Tukey's test was used for differentiating or comparing, depending on the circumstances. The obtained results suggested a visible light phototherapeutic effect that could be used as a microorganism inactivation method for the studied microorganisms. In some approaches, the biostimulation effect might also be a very interesting effect to be considered. This study supports the relevance of understanding the important role that phototherapy plays as a useful method for microbiological control studies and applications.