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.

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.