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Different strategies are reported in the literature for energy saving in Closed Plant Production Systems (CPPS). However, not reliable evidences about energy consumption with the use of pulsed LED light technique in lighting system available in Plant Factory and Vertical Farm. In this work, three key points to determine the effects of pulsed LED light versus continuous LED light are presented: (1) A mathematical model and its practical application for stabilizing the energy equivalence using LED light in continuous and pulsed mode in different light treatments. (2) The quantum efficiency of the photosystem II was used to determine positive and/or negative effects of the light operating mode (continuous or pulsed) on chili pepper plants (Capsicum annuum var. Serrano). (3) Evaluation of energy consumption with both operation modes using ten recipes from the literature to grow plants applied in Closed Plant Production Systems, different Photosynthetic Photon Flux Density at 50, 110, and 180 µmol m−2 s−1, Frequencies at 100, 500, and 1000 Hz, and Duty Cycles of 40, 50, 60, 70, 80, and 90%. The results show no significant statistical differences between the operation modes (continuous and pulsed LED light). For each light recipe analyzed, a pulsed frequency and a duty cycle were obtained, achieving significant energy savings in every light intensity. The results can be useful guide for real-life applications in CPPS.

New types of lighting have become available for culturing algae in recent years. LED lighting is very attractive for algal culturing. Algae grown in diffuse natural sunlight, traditional fluorescent lights, “White” LEDS and horticultural LED Grow Lights were compared in vivo (integrating sphere) and DMSO solvent extracts. Minor pigmentation changes were found in Chlorella sp (Chl a + b) (Chlorophyta) but large changes were found in the haptophyte Isochrysis sp (Chl a + c2); the diatom Chaetoceros calcitrans (Chl a + c1c2) and the chlorobacterium Acaryochloris marina (Chl d + a). There were large changes in carotenoids in Isochrysis and Chaetoceros under white LED. Grow Light LEDs increased carotenoid content in Isochrysis, Chaetoceros and Acaryochloris but to a much lesser extent in Chlorella and Synechococcus R-2 (Cyanophyta). The Blue cyanobacterial pigment, phycocyanin, found in Synechococcus R-2 and Acaryochloris in fluorescent light, “white” light LEDs and diffuse sunlight was partially suppressed in Synechococcus under LED Grow Lights but almost absent in Acaryochloris grown under LED Grow Lights. LED Grow Lights and to a lesser extent fluorescent lights and White LED lights encouraged synthesis of Blue and Green absorbing aquaculturally important carotenoids with lesser effects on enhancement of synthesis of Chls c2 and c1c2 (Isochrysis & Chaetoceros). LED Grow Lights had little effect on respiration of Chlorella but there was a consistent large increase in respiration under Grow Lights in all the other species. Light sources with large amounts of Blue light (fluorescent lights, White LEDs) are more realistic for oceanic photosynthesis than diffuse sunlight or LED Grow Lights. Ironically, despite the extremely irregularly spiked quantum spectrum of older technology conventional fluorescent lights, they proved to be better culture light sources than lighting based on LED technology (LED white lights and LED Grow Lights) for some algae.

While blue LED (b-LED) light is increasingly being studied for its cytotoxic activity towards bacteria in therapy of skin-related infections, its effects on eukaryotic cells plasticity are less well characterized. Moreover, since different protocols are often used, comparing the effect of b-LED towards both microorganisms and epithelial surfaces may be difficult. The aim of this study was to analyze, in the same experimental setting, both the bactericidal activity and the effects on human keratinocytes. Exposure to b-LED induced an intense cytocidal activity against Gram-positive (i.e, Staphylococcus aureus) and Gram-negative (i.e., Pseudomonas aeruginosa) bacteria associated with catheter-related infections. Treatment with b-LED of a human keratinocyte cell line induced a transient cell cycle arrest. At the molecular level, exposure to b-LED induced a transient downregulation of Cyclin D1 and an upregulation of p21, but not signs of apoptosis. Interestingly, a transient induction of phosphor-histone γ-H2Ax, which is associated with genotoxic damages, was observed. At the same time, keratinocytes underwent a transient epithelial to mesenchymal transition (EMT)-like phenotype, characterized by E-cadherin downregulation and SNAIL/SLUG induction. As a functional readout of EMT induction, a scratch assay was performed. Surprisingly, b-LED treatment provoked a delay in the scratch closure. In conclusion, we demonstrated that b-LED microbicidal activity is associated with complex responses in keratinocytes that certainly deserve further analysis.

Chlorella vulgaris, Chlorella pyrenoidosa, Scenedesmus quadricauda and Scenedesmus obliquus are representative green microalgae which are widely reported for algal production. In this study, we provide a systematic investigation of the biomass productivity, photosynthetic pigments, chlorophyll fluorescence and fatty acid content of the four green microalgae. The strains were grown in two primary monochromatic light wavelengths [red and blue LEDs (light emitting diode)], and in white LED conditions, respectively. Among them, blue LED light was determined as the best light for growth rate, followed by red LED and white LED. The chlorophyll generation was more sensitive to the monochromatic blue light. The polyunsaturated fatty acids (PUFAs) such as α-linolenic acid (18:3), which were perfect for human nutrition supplementation, showed high concentrations in these algae strains under blue LED. Collectively, the results indicate that the blue LED is suitable for various food, feed, and algal biofuel productions due to both biomass and fatty acid productivity.

The biotechnology industry plays a crucial role in the advancement of agronomy, contributing increasingly to each stage of its development. Microbial bioprospecting is a highly diverse field with significant agroindustrial potential, as nature provides a vast range of microorganisms suitable for such applications — including lipase-producing strains. As part of an initiative to establish a fungal collection at the Universidade do Estado de Minas Gerais (UEMG) – Passos Unit, 22 fungal isolates were obtained from various natural sources, 17 of which demonstrated lipase production. Fungal isolates with the highest lipolytic activity were derived from wet soil in calf paddocks, oral residues from calves post-nursing, and treated sewage sludge. This study introduces a standardized method using LED light for detecting lipolytic activity — a technique that to the best of our knowledge has not previously been applied to microorganisms. LED light presents a safer alternative to UV light, which can compromise sample integrity and pose health risks to users. This novel approach highlights the diversity of lipase-producing fungi from distinct environmental sources. The study aims to evaluate and qualitatively assess fungal enzymatic activity through this innovative methodology, facilitating the selection of strains with high enzymatic potential for agroindustrial applications.

In city farming, when growing green crops, a significant part of the production cost is the cost of electricity for lighting. The physiology, biochemistry, morphology and productivity of plants can be affected by changing irradiation modes and these changes reduce electricity costs. However, the results of studies in the literature are contradictory. In this work, we investigated the effect of impulse (frequency 1000 Hz and duty cycle 67%), scanning (the principle of running lights) and constant 16 h and 24 h modes of operation of white light LED irradiators on the physiological, biochemical and morphometric parameters of lettuce with red and green leaves. The daytime integral of light in all variants remained unchanged ~15.6 mol m−2 day−1. Daily electricity consumption also did not differ significantly. Plants were grown on racks in a climatic chamber up to 35 days of age. For lettuce with red leaves, the most optimal for biomass accumulation and synthesis of anthocyanins was the impulse illumination mode, while for lettuce with green leaves, no statistically significant differences in biomass were observed under different irradiation modes. For red-leaved lettuce, it was found that the highest concentration of carotenoids in the leaf was observed under constant (24 h) and scanning irradiation, which is associated with a more active reaction of the photosynthetic system to prolonged irradiation and increased intensity during scanning irradiation. Also, increased photosynthetic activity was found in both varieties of lettuce at 16 h of operation of LED irradiators, which, however, did not affect their final productivity. The results may be useful for the development of LED illuminators for use in rack growing.

The light spectrum effect on the cultivation efficiency of the microalgae strain Stichococcus sp. is explored, as a means of potentially intensifying the biomass productivity and regulating the cellular composition. Stichococcus sp. batch culture experiments, within a 3 L bench-top photobioreactor (PBR), are designed and implemented under different light spectrum profiles (i.e., cool white light (WL), cool white combined with red light (WRL), and cool white combined with blue light, (WBL)). The obtained results indicate that the studied strain is capable of adapting its metabolite profile to the light field to which it is exposed. The highest biomass concentration (3.5 g/L), combined with intense carbohydrate accumulation activity, resulting in a respective final concentration of 1.15 g/L was achieved within 17 days using exclusively cool white light of increasing intensity. The addition of blue light emitting diodes (LED) light, combined with appropriately selected culture conditions, contributed significantly to the massive synthesis and accumulation of lipids, resulting in a concentration of 1.43 g/L and a respective content of 46.13% w/w, with a distinct impact on biomass, carbohydrates and proteins productivity. Finally, a beneficial contribution of red LED light to the protein synthesis is recognized and this can be conditionally amplified provided nitrogen sufficiency in the culture medium.

Powdery mildew fungi infect plant leaves, reducing the yield of infected melon plants. Therefore, an eco-friendly method of controlling powdery mildew in melon plants needs to be developed. A previous study described how the morphological characteristics of the conidiophores of the melon powdery mildew fungus Podosphaera xanthii Pollacci (designated KMP-6N) grown under greenhouse (natural) conditions and red light-emitting diode (LED) irradiation differed from those grown under growth chamber conditions and blue LED irradiation. In the present study, conidiophores with unconstricted conidia under blue light were collected and inoculated onto host leaves through micromanipulation; the unconstricted conidia germinated and infected the leaves, producing vigorously elongated hyphae. The number of conidia collected, the initial times of conidial release from single colonies, and the number of conidia remaining in chains on conidiophores were examined with electrostatic techniques. Under red light, the number of collected conidia gradually increased with the light irradiation period. The initial conidial release occurred between 2 to 4 h; the number of conidia remaining on the conidiophores gradually decreased and, eventually, the conidiophore lengths became shorter. In contrast, under blue light, few conidia were collected at any given time; the number of conidia on the conidiophores gradually increased and, eventually, the conidiophore lengths became longer. Next, the effects of red and blue light on the spread of powdery mildew infection by placing a KMP-6N-infected melon seedling at the centre of a tray containing healthy melon seedlings were examined. Almost all healthy seedlings caused powdery mildew symptoms at ca. 21 days after red light irradiation, whereas only healthy seedlings near the infected seedlings showed symptoms after blue light irradiation. Thus, the spread of melon powdery mildew infection clearly differed between red and blue light irradiation. This is the first report describing the effects of red and blue light on the spread of P. xanthii infection from a single infected seedling to healthy host seedlings; their results provide insight into the ecological mechanisms of powdery mildew conidial scatter from conidiophores.

We evaluated the effect of monochromatic and combined light emitting diode (LED) light colour on performance, ovarian morphology, and reproductive hormone and biochemical blood parameters in laying hens. A total of 600 Hy-line Brown pullets, 12 weeks of age, were divided (25×4×6 = birds × replications × treatments) as follows: red (R), green (G), blue (B), and combinations of R → G and R → G → B treatments. Fluorescent white light (W) was the control. The results showed that higher egg production was found under the monochromatic R and combination R → G treatments, and that heavier eggs were laid by the B and G treatments (P<0.05). Consequently, better feed conversion ratio was attained in the R → G treatment. Serum follicle stimulating hormone and 17 -estradiol levels were significantly higher in the R and R → G treatments. B treated birds came into production 15 days later than those treated with R light. Organ weight (ovary and stroma) and ovarian follicle numbers (1-3 and 4-6 mm) were significantly higher in R treated birds, as well as serum glucose and triglyceride contents. Serum IgG concentrations and the heterophil to lymphocyte ratio were not influenced by light colour. In these laying hens, 14 h R with 2 h G light in the later part of the day increased reproductive hormone levels, ovarian weight, and follicle number and hence increased egg production. Thus, these results suggest that a combination of R → G light may be comparable with monochromatic R light to enhance egg production in laying hens.

In the present work, we have synthesized GdVO4 doped Eu3+ using a facile sol-gel method and analysed the effect of concentration variation and annealing temperature on the optical properties. Tetragonal (I41/amd) zircon type crystal structure of the material was confirmed by x-ray diffraction (XRD) study. The photoluminescence (PL) spectra were recorded with an ultraviolet (UV) excitation of wavelength 325 nm. GdVO4 doped Eu3+ (1 mol%) gives prominent red emission. This optimized sample was annealed at different temperature and as annealing temperature raises, the crystallinity of the material increases resulting in the improved emission intensity. The emission spectra of this phosphor exhibit intense peaks at wavelengths 593 nm (orange) and 618 nm (red) which corresponds to 5D0-7F1, 5D0 -7F2 transitions of Eu3+ ions. 5D0 -7F2, the electric dipole transition is dominant indicating that Eu3+ ions situated at a non-centrosymmetric site in the crystal structure. GdVO4: Eu3+(1 mol%) annealed at 800 °C gives eminent red emission which can be further used as the potential candidate for bioimaging, lighting, temperature sensing and display devices.