Effect Of Different Light Intensities Research Articles

ACCUMULATION OF POLYPHENOLS AT THE BEGINNING OF PHOTOMORPHOGENESIS IN VITRO TEA PLANT CULTURES UNDER THE INFLUENCE OF DIFFERENT LIGHT INTENSITY

Introduction. An important direction in the biotechnology of plant cell cultures is the search for factors and influences that contribute to increasing the accumulation of pharmacologically valuable metabolites in them, including polyphenols. These factors include light, the effect of which activates the processes of photomorphogenesis in in vitro cultures, regulates their differentiation and metabolic processes. All this depends on the intensity of the light flux, the origin of the cells and tissues cultivated in vitro, as well as the economic value of the synthesized plant metabolites. One of the promising pharmacologically valuable crops are tea plants (Camellia sinensis L.), as well as callus cultures initiated from them, which are characterized by the accumulation of various polyphenols, including flavans – substances with P-vitamin capillary-strengthening activity. The aim of the study was to compare the effect of different light intensity on the morpho-physiological characteristics of tea callus cultures, as well as the accumulation and localization of polyphenols in them. Material and methods. The object of the study was tea callus cultures of stem origin grown for 40 days at light intensity: 50 µmol·m2·s1, 75 µmol·m2·s1 and 100 µmol·m2·s1 (low, medium and high intensity, respectively). Morphophysiological parameters of calluses (color, density, water content), the total phenolics and flavans content in them, as well as their localization were analyzed. Results. The cultivation of tea calluses in the light was accompanied by their changing-over to photomorphogenesis, which manifested itself in the greening of the cultures and the chloroplasts formation in cells. The greatest efficiency of this process was noted at the high light intensity, which cor-related with the maximum accumulation of polyphenols and flavans, exceeding that in cultures grown at lower light flux values. Consequently, the cul-tivation of tea callus cultures at different light intensities makes it possible to regulate the polyphenols accumulation in them – biologically active plant metabolites with antioxidant activity.

Warming induced shade tolerance to become a key trait in invasion success of free-floating plant Pistia stratiotes over the native Hydrocharis morsus-ranae

Changes in nutrient concentration, temperature and light intensity due to climate change can alter the species composition of aquatic ecosystems, since global climate change can intensify the process of eutrophication. Eutrophication can enhance the biological invasion and the distribution of alien aquatic plants. Here we investigated the competition ability of alien Pistia stratiotes and native Hydrocharis morsus-ranae and the effect of different light intensities, temperatures and nutrient concentrations on the functional traits of the two species. In short term (8 days) monoculture experiment, we applied low (0.5 mg L-1 N; 0.05 mg L-1 P) and high nutrient concentrations (2 mg L-1 N; 0.2 mg L-1 P), four different light intensities (25–295 μmol m−2 s−1) as well as cold and warm (21.5; 27.5 ± 0.5°C) water treatments in full factorial design. In mixed cultures we cultivated the plants for 28 days with various biomass ratio, in shaded and well illuminated conditions, at a high nutrient concentration (4 mg L-1 N 1 mg L-1 P). In monocultures, the relative growth rate of P. stratiotes in warm water was significantly higher than that of H. morsus-ranae, however, this difference was not significant in colder water. In the co-culture experiment, P. stratiotes had significantly higher growth rate compared to H. morsus-ranae regardless of initial plant biomass ratio. Under shaded (65 ± 5 μmol m−2 s−1) conditions, P. stratiotes outcompeted H. morsus-ranae, resulting in its decay. Experimental results imply that with elevated temperature, the spread of alien P. stratiotes can be expected. Furthermore, under shaded conditions, P. stratiotes has a higher chance of occupying the water surface over the native plant H. morsus-ranae.

Gene expression regulation of the effect of shading on chlorophyll content in Fuding White Tea (Camellia sinensis L.).

Shading is an important practical method to improve the quality of green tea. Previous research of our group found that because the biosynthesis and distribution of theanine in tea plants were affected by down regulation of gene encoding amino acid permeases, theanine content in tea leaves which grown under shading condition was significantly higher than those under natural light. In this study, our group analyzed the changes of tea leaf area, free amino acid content and photosynthetic parameters under natural light and shading conditions, to ensure that moderate shading did not reduce but improve the quality of tea. Transcriptome sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted to reveal the expression levels of genes related to chlorophyll content and chlorophyll a/b ratio under natural light and shading conditions. Experimental results revealed the presence of the following differentially expressed genes (DEGs) in the porphyrin and chlorophyll metabolism pathway of tea under natural light and shading conditions: the up regulation of CPOX expression may lead to an increase in the accumulation of raw materials of chlorophyll synthesis, while the down regulation of SGR expression may lead to a decrease in chlorophyll degradation. The combined effect of these two genes may lead to an increase in the total chlorophyll content of tea. The down regulation of NOL expression may lead to the obstruction of chlorophyll b transform to chlorophyll a, that is, the decrease of the chlorophyll a/b ratio. This study investigated the molecular mechanism of chlorophyll content and component alteration in Fuding white tea under natural light and shading conditions, and elucidated the effects of different light intensities on the porphyrin and chlorophyll metabolism pathway of tea. Thus provided deep understanding of chlorophyll regulation under shading condition in tea cultivation, which could contribute to high-quality matcha production.

Effects of different light intensity on leaf color changes in a Chinese cabbage yellow cotyledon mutant.

Leaf color is one of the most important phenotypic features in horticultural crops and directly related to the contents of photosynthetic pigments. Most leaf color mutants are determined by the altered chlorophyll or carotenoid, which can be affected by light quality and intensity. Our previous study obtained a Chinese cabbage yellow cotyledon mutant that exhibited obvious yellow phenotypes in the cotyledons and the new leaves. However, the underlying mechanisms in the formation of yellow cotyledons and leaves remain unclear. In this study, the Chinese cabbage yellow cotyledon mutant 19YC-2 exhibited obvious difference in leaf color and abnormal chloroplast ultrastructure compared to the normal green cotyledon line 19GC-2. Remarkably, low-intensity light treatment caused turn-green leaves and a significant decrease in carotenoid content in 19YC-2. RNA-seq analysis revealed that the pathways of photosynthesis antenna proteins and carotenoid biosynthesis were significantly enriched during the process of leaf color changes, and many differentially expressed genes related to the two pathways were identified to respond to different light intensities. Remarkably, BrPDS and BrLCYE genes related to carotenoid biosynthesis showed significantly higher expression in 19YC-2 than that in 19GC-2, which was positively related to the higher carotenoid content in 19YC-2. In addition, several differentially expressed transcription factors were also identified and highly correlated to the changes in carotenoid content, suggesting that they may participate in the regulatory pathway of carotenoid biosynthesis. These findings provide insights into the molecular mechanisms of leaf color changes in yellow cotyledon mutant 19YC-2 of Chinese cabbage.

Effect of different light intensities on agronomic characteristics and antioxidant compounds of Brassicaceae microgreens in a vertical farm system

Microgreens are vegetable or edible herb shoots harvested in the early stages of development. They have an important number of bioactive compounds and add color, texture, and flavor to dishes and salads. Given their benefits, small size, and high market prices, they can grow in indoor systems, where light is determinant. This study aimed to evaluate the effect of different light intensities on agronomic characteristics, color, chlorophylls and carotenoids content, and antioxidant activity represented by total phenolic content (TPC), eliminate, and antioxidant capacity (AC) in four Brassicaceae species in two colors (green and red). The experiment was conducted in a controlled light-emitting diode (LED) environment growth chamber (day/night temperatures of 25/20 ± 1.2°C, 16 h photoperiod, and 79 ± 2% relative humidity). Three light intensities were used for microgreen growth with the same LED light spectrum: low (120 ± 5.1 μmol m−2 s−1), medium (160 ± 3.6 μmol m−2 s−1), and high (210 ± 5.9 μmol m−2 s−1). Eight g of the seeds of green and red cultivars of cabbage, kale, mizuna, and mustard were sown in a plastic tray (64 cm x 35 cm x 6 cm) with a mixture of peat and perlite (1:2 = v: v). Overall, the high intensity increased dry matter percentage and dry weight, except in green and red kale and green cabbage cultivars. In contrast, low intensity promoted a larger hypocotyl in all species than with high intensity; moreover, it enhanced the cotyledon area in green and red mizuna. Cabbage, kale, and mustard green cultivars were greener under medium intensity, whereas the low intensity enhanced the purple color of mizuna. In addition, chlorophyll a and b increased under low intensity in most species except the red kale and mustard cultivars. The high intensity raises the antioxidant activity, promoting a higher TPC and AC. The findings revealed that the light intensity generated variations in agronomic characteristics, color, chlorophyll content, and antioxidant activity of Brassicaceae microgreens, and the changes were based on the specific species and cultivars.

Effect of light intensity on celery growth and flavonoid synthesis.

Light is one of the important environmental factors affecting the growth and development of facility vegetables. In this experiment, we investigated the effects of different light intensities on the growth, nutritional quality and flavonoid accumulation of celery under hydroponic and full LED light conditions. Four light intensities of 40, 100, 200, or 300 µmol·m-2·s-1 were set up in the experiment, and three harvest periods were set up on the basis of different light intensities, which were 15, 30, and 45 d after treatment (labeled as S1, S2, and S3, respectively). The results showed that the plant height and aboveground biomass of celery increased with the increase of light intensity, and the light intensity of 200 μmol·m-2·s-1 was beneficial to increase the contents of chlorophyll, carotenoids, total phenols, vitamin C, cellulose, total flavones and apigenin in celery. During the S1-S3 period, the activities of PAL, CHS, CHI and ANS increased gradually under 200 and 300 μmol·m-2·s-1 light intensity treatments, and the activities of FNS and CHS enzymes were the highest under 200 μmol·m-2·s-1 light intensity treatment. The expression and ANS activity of Ag3GT, a key gene for anthocyanin synthesis, reached the maximum value at 300 μmol·m-2·s-1, and the expression level and FNS activity of AgFNS, a key gene for apigenin synthesis, reached a maximum value at 200 μmol·m-2·s-1. In general, the anthocyanin content was the highest at 300 μmol·m-2·s-1, and the apigenin content was the highest at 200 μmol·m-2·s-1. In conclusion, light intensity of 200 µmol·m-2·s-1 treatment was more favorable for celery growth and nutrient synthesis.

The potential mechanism of response to light intensity in energy metabolism mediated by miRNA in Isatis indigotica

Light is the main source of energy for plant growth. Studies have shown that I. indigotica is a light-demanding plant and its yield and various active components are positively correlated with light intensity, but no studies of light intensity affecting energy metabolism in I. indigotica have been reported. Mitochondria are the main site of energy metabolism, and miRNAs are important factors in regulating gene expression, this experiment attempts to study the effects of different light intensities on energy metabolism from the perspective of mitochondria and miRNAs. The results show that the biomass、mitochondrial structural integrity and energy metabolism in I. indigotica were found to be positively correlated with light intensity. Small RNA and transcriptome sequencing identified 241 miRNAs and 36,372 mRNAs, and degradomic technology identified 72 miRNAs targeting 106 mRNAs, among which 12 pairs of miRNA-mRNAs were annotated on mitochondria. Combined with RT-qPCR validation, it was concluded that miR167a-5p positively regulates LETM1 and affects mitochondrial structure, miR400-5p and mIR169m-p3_1ss15CT negatively regulate GRXS15 and CMC4, respectively, affecting SDH and CCO activities, and miR395a-APS4 may affect the utilization of ATP and sulfate assimilation. In summary, the results of this study complement and enrich knowledge of light effects on mitochondria from the perspective of miRNA, while providing guidance for the cultivation of I. indigotica.

Effects of different light intensity on the growth of tomato seedlings in a plant factory.

Light-emitting diodes (LEDs) were the best artificial light source for plant factories. Red light-emitting diodes (LEDs, R) and blue light-emitting diodes (LEDs, B) were used to obtain different light intensities of uniform spectra, and the greenhouse environment was considered as a comparison. The results showed that root dry weight, shoot dry weight and stem diameter were superior in plant growth under 240 μmolm-2s-1, additionally, the Dixon Quality Index (DQI) was also best. Under 240 μmolm-2s-1, the net photosynthesis rate (Pn) was consistent with the greenhouse's treatment, superior to other experimental groups. The results implied that the PPFD was more suitable for the cultivation of tomato seedlings under the condition of 240 μmolm-2s-1, and can replace the greenhouse conditions so as to save energy and reduce emissions.

A study of spatial rationality in the architectural design of senior citizen apartments in terms of calculation and biological effects

Abstract This paper is based on the photobiological effect of the role of the collation of different light colors under the elderly pupil change and the luminance level function of the relationship between the equation so as to use this for the rationality of the design of the elderly housing. The non-visual direct response (nvRD) model is also used to predict the relative non-visual response to light and to compare the relative effectiveness of different light modes in providing potential health benefits to humans. The effects of different light illumination on mood affectivity and visual comfort were calculated using the modified spatial contrast (mSC) model and the preliminary gaze response light drive (GRL) model. Finally, the effects of different light intensities and situations on the physical heart rate and cardiovascular indexes of the elderly were examined using the experimental design of photobiological effects. The results showed that the T-wave time under green light increased by 4.008 ms on average, and the QT band interval under red light and green light had a more obvious increase, with an average increase of 5.131 ms for red light and 7.238 ms for green light, while the ventricular rate under blue light showed signs of acceleration, with an average increase of 2.352 beats. The rational design of space in elderly apartments is supported by theoretical reference and data basis in this paper.

LED red and blue light intensity affected productivity and nitrogen metabolisms of ryegrass

Light intensity plays a critical regulatory role in determining plant yield and quality, and energy consumption in plant factory with artificial light (PFAL). The effects of different light intensities (200, 300, 400, 500, and 600 µmol·m−2·s−1) of light-emitting diodes (LED) red and blue light with ratio 4:1 on growth, quality, nitrogen and amino acid metabolisms of ryegrass were investigated. The results showed the tiller number and shoot fresh weight in ryegrass were increased, while plant height and stem diameter remained stable with the improvement of light intensity. The highest levels of soluble protein, free amino acid, and DPPH free radical clearance rate in photon flux density (PPFD) at 500 µmol·m−2·s−1, and then significantly decreased with light intensity increased. The highest soluble sugar content was found at PPFD of 600 µmol·m−2·s−1, while malondialdehyde (MDA) content remained stable in all treatments. As the light intensity increased, nitrate content decreased, while nitrate reductase (NR) activity and the ammonium content increased. As light intensity was increased from 200 to 600 µmol·m−2·s−1, nitrite reductase (NiR) activity first decreased and then increased. Moreover, glutamate and cysteine contents increased first and then decreased, while glutamate synthase (GOGAT), glutamine synthase (GS), glutamate dehydrogenase (GDH), and cysteine synthases (CS) activities increased continuously with light intensity. Light intensity was significantly correlated with the parameters of growth, quality, nitrogen and amino acid metabolisms in ryegrass. It was recommended that PPFD at 400–500 µmol·m−2·s−1, photoperiod of 16 h/d was suitable for ryegrass high-efficient production in PFAL with relatively low energy cost.

Effect of abiotic factors on pathotypes causing yellow and brown rust in wheat

An attempt was made to determine the most favourable abiotic factors influencing germination of urediniospores of different pathotypes of Puccinia species. The causal organism of rusts in wheat is Puccinia spp. Five pathotypes of Puccinia striiformis (46S119, 78S84, 110S84, 110S119, 238S119) causal organism of yellow rust and two pathotypes of Puccinia triticina (77-5 and 77-9) causal organism of brown rust in wheat were obtained from Department of Plant Pathology, Punjab Agricultural University, Ludhiana. The data related to spore germination on agar slides was analysed and the levels of urediniospores germination at different temperatures (5,10,15 and 20oC) and pH (5,6,7 and 8) for each pathotype was compared using analysis of variance. The most appropriate temperature and pH were later used to conduct an experiment to study effect of different light intensities (500, 750,1000 and 1250 lux) on spore germination of all the pathotypes under study. The data showed that on agar, 15°C was proved as most suitable for urediniospore germination for Puccinia striiformis. Mean per cent spore germination was highest over the temperature range 15°C (43.55%) for Pst pathoypes and dropped significantly at 10°C (37.97%), 20°C (29.66%) and 5°C (21.04%). Mean urediniospore germination for Puccinia triticina was highest at 20°C (43.89%) followed by 15°C (39.44%), 10°C (30.43) and 5°C (27.39% ). Experimental results revealed that per cent spore germination was better under pH 7 followed by 6, 5 and 8 for all the pathotypes considered for study. The highest urediniospore germination was observed for 1250 lux (46.54%) followed by 1000 lux (41.29%), 750 lux (38.42%) and 500 lux (27.60%).

The Effect of Different Light Intensities on the Growth and Yield of Tomato (Lycopersicon Esculentum Mill.)

Tomato (Lycopersicon Esculentum Mill.) is one of the popular fruit vegetables, especially rich in vitamins, minerals, and antioxidants. Inconsistent light intensity, due to unfavorable weather conditions, reduced tomato performance. Response of one tomato variety (Diamante Max F1), under different light intensities (T1: Control, T2: Single net T3: Double net,) was assessed in field trials. The experimental design was a randomized complete block design (RCBD). Effects of different light intensities were measured in terms of plant height, number of days to flower, number of fruits, the weight of fruits, yield per hectare, and light intensity received in every treatment. All results were significantly different at a 1% level of significance for all parameters. Treatment 2 manifested the highest mean for plant height, treatment 1 for the number of days to flower, and treatment 3 for the number of fruits. Treatment 3 obtained the highest yield per hectare and Treatment 1 for the highest light intensity received per treatment. Treatment 2 has the least mean for all parameters measured, in conclusion, the effect using a double net is highly recommended in tomato production.

Antioxidant Activities of Photoinduced Phycogenic Silver Nanoparticles and Their Potential Applications.

While various methods exist for synthesizing silver nanoparticles (AgNPs), green synthesis has emerged as a promising approach due to its affordability, sustainability, and suitability for biomedical purposes. However, green synthesis is time-consuming, necessitating the development of efficient and cost-effective techniques to minimize reaction time. Consequently, researchers have turned their attention to photo-driven processes. In this study, we present the photoinduced bioreduction of silver nitrate (AgNO3) to AgNPs using an aqueous extract of Ulva lactuca, an edible green seaweed. The phytochemicals found in the seaweed functioned as both reducing and capping agents, while light served as a catalyst for biosynthesis. We explored the effects of different light intensities and wavelengths, the initial pH of the reaction mixture, and the exposure time on the biosynthesis of AgNPs. Confirmation of AgNP formation was achieved through the observation of a surface plasmon resonance band at 428 nm using an ultraviolet-visible (UV-vis) spectrophotometer. Fourier transform infrared spectroscopy (FTIR) revealed the presence of algae-derived phytochemicals bound to the outer surface of the synthesized AgNPs. Additionally, high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) images demonstrated that the NPs possessed a nearly spherical shape, ranging in size from 5 nm to 40 nm. The crystalline nature of the NPs was confirmed by selected area electron diffraction (SAED) and X-ray diffraction (XRD), with Bragg's diffraction pattern revealing peaks at 2θ = 38°, 44°, 64°, and 77°, corresponding to the planes of silver 111, 200, 220, and 311 in the face-centered cubic crystal lattice of metallic silver. Energy-dispersive X-ray spectroscopy (EDX) results exhibited a prominent peak at 3 keV, indicating an Ag elemental configuration. The highly negative zeta potential values provided further confirmation of the stability of AgNPs. Moreover, the reduction kinetics observed via UV-vis spectrophotometry demonstrated superior photocatalytic activity in the degradation of hazardous pollutant dyes, such as rhodamine B, methylene orange, Congo red, acridine orange, and Coomassie brilliant blue G-250. Consequently, our biosynthesized AgNPs hold great potential for various biomedical redox reaction applications.

Effects of different light intensity on growth, feeding, retinal structure and expression of vision-related genes of silver pomfret

The intensity of light has been known to play a crucial role in the growth and developmental processes of fish through the visual system. To investigate effects of light intensity on the growth, feeding patterns, retinal structure, and vision-related genes of silver pomfret, we set four groups including control (natural light), L0 (darkness), L100 (100 lux), and L1000 (1000 lux) at larval, juvenile and young stages. Full length and survival rate were significantly lower in L0 at larval and juvenile, while feeding rate was significantly higher in control and L1000; at young stage, weight and feeding rate was significantly lower in L0 and specific growth rate was significantly higher in control; but there was no significant difference in condition factor among four groups. Next, at larvae stage, we observed a clear ten-layer structure of the retina, which developed better in high light intensity groups; the number of melanin particles in pigment epithelial layer also increased with development of retina; at juvenile and young stages, low light intensity led to aggregation of melanin particles, and thickness of ganglion cell layer became thinner, with cell body decreasing to one layer in high light intensity groups. Finally, we examined expression of seven vision-related genes: RH1 gene was up-regulated at larvae stage and down-regulated at juvenile and young stages in L0 and L100, and RH2 and LWS initially increased and then declined with the development of the fish in control; conversely, SWS, SWS2, RPE65, and RBP were up-regulated in high light intensity groups. In conclusion, our study suggests that high light intensity can lead to improved growth and feeding patterns in fish, as well as promoting the development of retina and up-regulating the expression of pigment genes. Consequently, our findings provide a valuable theoretical foundation for optimizing the lighting scheme of the artificial breeding process of silver pomfret.

Effects of Light Intensity on in Vitro Regeneration Of Stevia Rebaudiana Bertoni, Bacopa Monnieri L. And Solanum Tuberosum L.

Light is the most essential factor controlling plant growth, morphogenesis, metabolism and chlorophyll content of plant cells, tissues and organ culture. The present investigations were carried out to find out effects of different light intensities (210, 500, 1000, 1500, 2000, 2500 and 3000 lx) on the regeneration of three plants, namely Stevia rebaudiana Bertoni., Solanum tuberosum L. and Bacopa monnieri L. Results showed that light intensity has a direct effect on plant growth in vitro. There was less time for shoot initiation and the highest mean number of shoots/explants (9.75 ± 3.862) of S. rebaudiana was observed from the nodal explants when the culture was maintained at 1000 lx light conditions. At maximum light intensity (3000 lx) best result was recorded for S. tuberosum. A distinct intensity of light, 1500 lx showed the best outcome both for the number and length of shoots of B. monnieri (p = 0.00). The present study also demonstrated the relationship between root growth and light condition. Bangladesh J. Bot. 52(1): 53-60, 2023 (March)

Effect of different light intensities on prolactin and cortisol plasma concentration in farming African catfish (Clarias gariepinus) in RAS with low-water exchange

In the Bulgarian aquaculture sector, focusing research efforts on the technical specifications of the cultivation of African catfish (Clarias gariepinus) is important due to the need for more information. We aimed to assess the impact of light intensities on prolactin and cortisol levels as stress markers in African catfish. Fish were acclimated over an appropriate period to the short photoperiod (16D and 8L) and then distributed randomly to three groups, each separated by sex. Fish exposed to different light intensities (63, 51, and 40 lux, respectively) were followed for 45 days by lux meter. Blood samples were collected from the caudal vein using a 2 ml K2EDTA-coated syringe. A laser fluorescence reader assayed plasma prolactin and cortisol. The pituitary was removed from anesthetized fish and fixed for histological examinations. The results of our study suggest that increasing light intensity increases prolactin and cortisol levels in African catfish.

Effect of different light intensities and colors on growth performance and reproductive characteristics in Japanese quails

Effect of different light intensities and colors on growth performance and reproductive characteristics in Japanese quails

Effects of light intensity and photoperiod on the cultivation of the soft coral Sarcophyton trocheliophorum

Coral reefs are one of the most diverse, productive ecosystems in the world, and light plays crucial role in its survival. Notably, the effects of light conditions on soft coral and its adaptive mechanism were unclear. Thus, the present study aimed to investigate and evaluate the effects of different light intensities (30, 80 and 130 μmol m−2 s−1) and photoperiods (18D:6L, 12D:12L and 6D:18L) on cultivation of soft coral Sarcophyton trocheliophorum. During two 50-day of the experiments, we monitored the zooxanthellae density, Chl a content, enzyme activities (SOD, CAT and GST) and microbial diversity of S. trocheliophorum. Our study's outcomes found that, at the end of the experiment, the 80 μmol m−2 s−1 light intensity group and 12D:12L photoperiod group both possessed the highest zooxanthellae density (2.54 × 108 ± 0.14 × 108 cells g−1 DW and 2.40 × 108 ± 0.07 × 108 cells g−1 DW, respectively), Chl a content (295.01 ± 14.13 μg g−1 DW and 287.78 ± 16.13 μg g−1 DW, respectively) and microbial diversity and relatively stable enzyme activities level. Besides, we speculated that the reason for the decline of zooxanthellae density, Chl a content and microbial diversity under other light conditions might be that it induced light stress and caused oxidative damage. The main bacterial composition of S. trocheliophorum in different light conditions was similar at the phylum level, showing the stability of microbial community structure. Proteobacteria, Actinobacteria and Firmicutes were dominant under all light conditions, so we hypothesized that these bacteria phylum play a crucial role in coral growth and survival.In conclusion, compared with the other treatments, 80 μmol m−2 s−1 light intensity and 12D:12L photoperiod were more beneficial to the growth performance of S. trocheliophorum and could be recommended for its cultivation condition. Our study could provide helpful information for sustainable management plans for the cultivation and conservation of soft corals, which was especially important to the protection and restoration of degraded coral reefs.

Efficient Co-production of Docosahexaenoic Acid Oil and Carotenoids in Aurantiochytrium sp. Using a Light Intensity Gradient Strategy.

Aurantiochytrium is a promising source of docosahexaenoic acid (DHA) and carotenoids, but their synthesis is influenced by environmental stress factors. In this study, the effect of different light intensities on the fermentation of DHA oil and carotenoids using Aurantiochytrium sp. TZ209 was investigated. The results showed that dark culture and low light intensity conditions did not affect the normal growth of cells, but were not conducive to the accumulation of carotenoids. High light intensity promoted the synthesis of DHA and carotenoids, but caused cell damage, resulting in a decrease of oil yield. To solve this issue, a light intensity gradient strategy was developed, which markedly improved the DHA and carotenoid content without reducing the oil yield. This strategy produced 30.16g/L of microalgal oil with 15.11g/L DHA, 221µg/g astaxanthin, and 386µg/g β-carotene. This work demonstrates that strain TZ209 is a promising DHA producer and provides an efficient strategy for the co-production of DHA oil together with carotenoids.

Roles of illumination on distribution of phosphorus in Chlorella vulgaris under mixotrophic cultivation.

Phosphorus (P) is a non-substitutable resource and global reserves of phosphate rock are limited. In this study, phosphorus recovery by Chlorella vulgaris, and the effects of different light intensities (2000 Lux, 5000 Lux, 8000 Lux, 12,000 Lux) on the phosphorus distribution in the soluble microbial product (SMP), extracellular polymeric substance (EPS) and intracellular polymeric substance (IPS) were analyzed. The results showed that the 5000 Lux was the optimum light intensity for P uptake and transformation by Chlorella vulgaris under mixotrophic cultivation. At the light intensity of 5000 Lux, the P uptake rate was 100% after 32 days of cultivation, and the concentration of intracellular organic phosphorus (OP) was 5.77mgP/L. Moreover, EPS was the main P pool when inorganic phosphorus (IP) was depleted in bulk solution. Phosphorus recovery by microalgae is an important solution to treat P-containing wastewater.