Astaxanthin Content Research Articles

FATTY ACID PROFILE OF COMMON CARP (CYPRINUS CARPIO) AFTER ADDITION OF ASTAXANTHIN TO THE FEED MIXTURE

Astaxanthin is a very strong antioxidant typically fed to rainbow trout mainly to alter the color of its’ meat to red. In our study, we incorporate a relatively low concentration of astaxanthin into the diet of common carp to enhance the chemical parameters and oxidation stability of carp meat without altering the typical coloration of meat. Also, we observed the fatty acid profile of reared fish. We observed an increase in protein content in animals with astaxanthin dietary addition. It was not statistically significant, but we observed a lowering of fat content in experimental groups. Regarding lipid oxidation, we did not observe any significant effect of astaxanthin on malondialdehyde production in samples. Fatty acid profiles were determined by gas chromatography and then compared. Only significant differences were observed in stearic and arachidonic acid and in the experimental group with lower astaxanthin addition. Our results conclude that dietary astaxanthin has no adverse effect on fatty acid profile or oxidation stability during storage (at -18 °C). On the other hand, astaxanthin has the potential to enhance the protein and lower the fat content, even in low concentrations.

Dietary lipid and astaxanthin contents affect the pigmentation of Arctic charr (Salvelinus alpinus)

The most important quality parameter of salmonids is the red color of their skin and muscles. In this contribution, the effects of astaxanthin and dietary lipid content on the pigmentation of Arctic charr (Salvelinus alpinus) were studied. Charrs were fed on diets containing 40, 60, and 80 ppm synthetic astaxanthin together with 10, 18, and 26% dietary lipids for 24 weeks. Results indicated that the astaxanthin concentration in the belly skin and flesh of fish was strongly correlated with both carotenoid and dietary lipid contents, suggesting a significant interaction between diets and the total carotenoid concentration in the belly skin and flesh. The Hunter color L* values of the fillet and the belly skin were inversely related to their carotenoid levels, whereas their a* and b* values were strongly correlated with the total carotenoid concentration. The apparent digestibility coefficient of carotenoids was directly correlated with the level of dietary lipid but inversely correlated with carotenoid contents. A strong correlation between the content of carotenoids retained in the flesh and their digestibility was observed. Thus, the pigmentation of Arctic charr could improve the overall consumer acceptability as well as nutritional and potential market values of Arctic charr.Graphical

Effect of carrot juice on Haematococcus pluvialis growth and astaxanthin production

In this work, we report the use of carrot juice (CJ) as a source of carotenoids as precursors of astaxanthin in a microalga Haematococcus pluvialis culture medium. Three experiments were carried out, two with the culture media supplemented with CJ (1.62 g.mL−1) at the beginning of the vegetative phase, and at the peak of the cell growth; and a control (without CJ). The samples supplemented with CJ resulted in a biomass production (531.9 mg and 625.3 mg) higher than the control (445.9 mg). Similar results were observed in astaxanthin production, resulting in a considerably higher amount (8.54 and 7.71 ppm) in the experiments supplemented with CJ compared to the control (4.79 ppm). These results showed the potential of CJ use as an additive to significatively enhance both the biomass of H. pluvialis and astaxanthin content, especially when CJ is added at the beginning of the microalga culture.

Mechanism of melatonin and sodium orthovanadate regulating astaxanthin biosynthesis in Phaffia rhodozyma

Astaxanthin is a kind of carotenoids, which has strong antioxidant activity. It is widely used in food, chemical industry, medical treatment and other fields. Our previous research confirmed that carotenoids in Phaffia rhodozyma could be influenced by melatonin (MT) and sodium orthovanadate (SOV), but their metabolic regulation mechanism of astaxanthin biosynthesis was not clear. In this study, metabolic regulation mechanism of MT and SOV was explored by metabonomics and fermentation dynamics. The results showed that adding 1.54 mM SOV at 27.03 h and 7.49 mM MT at 36 h could improve the astaxanthin cell yield by 64.67 %, from 3.54 mg/g to 5.83 mg/g. SOV promoted carbon flux into astaxanthin synthesis pathway by inhibiting its activity by binding to glutamate dehydrogenase pocket and reducing the expression of arginine, glutamine and isoleucine in amino acid pathway. The regulation of MT increased the expression of fatty acid synthase, fatty acid desaturase and acetyl-CoA carboxylase in fatty acid pathway, thus increasing the accumulation of fatty acids. Fermentation dynamic kinetics showed SOV and MT effectively weakened the growth coupling limitation of carotenoid and astaxanthin synthesis, which increased the astaxanthin content by 22.52 % and 21.32 %, respectively. This study provided a theoretical basis for regulating the production of astaxanthin in Phaffia rhodozyma.

Synergistic and stepwise treatment of resveratrol and catechol in Haematococcus pluvialis for the overproduction of biomass and astaxanthin

To increase the production of biomass and astaxanthin from Haematococcus pluvialis to meet the high market demand for astaxanthin, this study recruited two typical and negligible phytohormones (namely resveratrol and catechol) for the stepwise treatments of H. pluvialis. It was found that the hybrid and sequential treatments of resveratrol (200 μmol) and catechol (100 μmol) had achieved the maximum astaxanthin content at 33.96 mg/L and 42.99 mg/L, respectively. Compared with the hybrid treatment, the physiological data of H. pluvialis using the sequential strategy revealed that the enhanced photosynthetic performance via the Calvin cycle by RuBisCO improved the biomass accumulation during the macrozooid stage; meanwhile, the excessive ROS production had occurred to enhance astaxanthin production with the help of NADPH overproduction during the hematocyst stage. Overall, this study provides improved knowledge of the impacts of phytohormones in improving biomass and astaxanthin of H. pluvialis, which shed valuable insights for advancing microalgae-based biorefinery.

Optimizing color enhancement in dried Penaeus vannamei through high-humidity hot air impingement cooking: Enzyme inactivation, reduced drying time, and Maillard reaction inhibition

This study was aimed to evaluate the potential of high-humidity hot air impingement cooking (HHAIC) on Penaeus vannamei, focusing on its drying characteristics, microstructure, water distribution, enzyme activity, astaxanthin content, antioxidant capacity, color, and Maillard reaction. Results demonstrated that a 3 min HHAIC significantly improved the shrimp's color and optimized astaxanthin content with a notable increase in scavenging capacity based on an in-vitro as antioxidation activity evaluation. Compared to the untreated samples, HHAIC could significantly inactivate polyphenol oxidase by 95.76%. Also, it suppressed the Maillard reaction by decreasing 5-hydroxymethylfurfural content and shortened the drying time by 40%. In addition, the low-field nuclear magnetic resonance and microstructure analysis showed alterations in the shrimp muscle fiber structure and water distribution. This study indicated that HHAIC could elevate quality, enhance appearance, and reduce the processing time of dried shrimp, presenting valuable implications for industry progress.

Pengaruh pemberian sampah organik terhadap pertumbuhan dan kandungan astaxanthin pada pupa black soldier fly (Hermetia illucens (Linnaeus))

Black soldier fly (Hermetia illucens (Linnaeus)) atau BSF merupakan serangga pengolah sampah organik yang fase larvanya memiliki kandungan nutrisi tinggi sehingga berpotensi sebagai sumber protein alternatif pakan dan pangan. Astaxanthin merupakan senyawa antioksidan yang lazim diperoleh dari tumbuhan, alga, dan Crustacea. Deteksi astaxanthin pada Bombyx mori (Linnaeus) menjadi titik tolak dugaan bahwa astaxanthin potensial ditemukan pada serangga lain termasuk BSF. Penelitian bertujuan untuk mempelajari pengaruh pemberian jenis pakan sampah organik terhadap pertumbuhan larva BSF dan kandungan astaxanthin pada pupa BSF. Desain penelitian menggunakan rancangan acak lengkap dengan 4 perlakuan jenis pakan sampah organik berupa sisa buah dan sayur (BS), ampas tahu (AT), sisa nasi (N), campuran sisa buah dan sayur, ampas tahu dan sisa nasi (C). Pakan ternak T51 digunakan sebagai kontrol. Setiap perlakuan pakan diulang 3 kali. Parameter penelitian terukur meliputi parameter pertumbuhan larva berupa berat, panjang, dan karakteristik larva; dan parameter kandungan senyawa kimia termasuk astaxanthin pada pupa BSF. Ekstraksi pupa dilakukan dengan metode maserasi triphasic menggunakan kombinasi 5 pelarut berupa n-heptane, etil asetat, acetonitrile, butanol-l, dan akuades, sedangkan identifikasi senyawa dilakukan menggunakan uji kualitatif terpenoid, uji thin layer chromatography (TLC), dan liquid chromatography-mass spectrometry (LC-MS). Hasil penelitian menunjukkan bahwa buah dan sayur (BS) paling berpengaruh meningkatkan pertambahan ukuran tubuh larva dengan berat 0,09 ± 0,04 gram/larva dan panjang 1,49 ± 0,31 cm/larva. Analisis LC-MS mendeteksi senyawa dereplikasi lutein, anisodamine, derivat resveratrol, dehydroarginine, dan senyawa dereplikasi astaxanthin dengan massa molekuler sebesar 597,23 m/z pada larva BSF yang diberi pakan buah dan sayur.

Novel paradigm of light and CO2 feeding to improve the ‎ co-production of ‎astaxanthin and polyunsaturated fatty acids in Haematococcus ‎pluvialis

This study aimed to develop an innovative paradigm of lighting and CO2 flow rate in dilution and photoinduction stages of H. pluvialis cultivation to overcome the cell number reduction and stimulate the astaxanthin and polyunsaturated fatty acids accumulation joined by carbon bio-sequestration. The appropriate paradigm of lighting to reach the maximum cell number, astaxanthin concentration, and astaxanthin content in the dilution and photoinduction stages was obtained 2-fold (300 µmol/m2/s) and 6-fold (900 µmol/m2/s) of the final light intensity in the phototrophy stage (150 µmol/m2/s), respectively. Under the inventive lighting paradigm, feeding the 225 mL/L/min CO2 recorded optimum consequences in the dilution and photoinduction stages. The cell number, astaxanthin productivity, lipid content, polyunsaturated fatty acid and CO2 bio-fixation rate at the end of the photoinduction stages by lighting/CO2 balance were 94 %, 96 %, 32 %, 61 % and 40 % higher than control, respectively. Additionally, the levels of omega-6 fatty acids and omega-3 fatty acids were 70 % and 73 % higher than the control, respectively. This substantial increase was achieved by maintaining an optimal ratio of omega-6 to omega-3 fatty acids (3.05). Furthermore, to maximize the cell growth of microalgae and enhance the accumulation of valuable metabolites through CO2 bio sequestration, it is recommended to focus on the CO2 flow rate parameter instead of the CO2 percentage. That is affected by both the CO2 percentage and the aeration rate. Our findings provide a promising cost-effective and ecofriendly approach to improve the co-production of astaxanthin and polyunsaturated fatty acids in H. pluvialis.

Prevention of the Quality Degradation of Antarctic Krill (Euphausia superba) Meal through Two-Stage Drying.

To achieve a krill meal of high quality, a two-stage drying involving hot-air drying and vacuum drying was investigated. Five experimental groups were established according to the different drying conditions in the second stage, including 95 °C and 101 kPa, 95 °C and 60 kPa, 75 °C and 101 kPa, 75 °C and 60 kPa, and 75 °C and 20 kPa. The results showed that reducing the drying temperature and vacuum pressure in the second stage had a significant impact on the drying characteristics, sensory quality, and bioactive compounds of krill meal. Among all five groups, the drying condition of 75 °C and 60 kPa maintained a high drying rate while preserving a phospholipid content of 30.01 mg/kg and an astaxanthin content of 37.41 mg/kg. It also effectively reduced the isomerization of astaxanthin and the oxidation of unsaturated fatty acids. These results suggested that the two-stage drying method may contribute to the production of high-quality krill meal.

A Study on the Effect of Various Media and the Supplementation of Organic Compounds on the Enhanced Production of Astaxanthin from Haematococcus lacustris (Girod-Chantrans) Rostafinski (Chlorophyta).

Natural astaxanthin is in high demand due to its multiple health benefits. The microalga Haematococcus lacustris has been used for the commercial production of astaxanthin. In this study, we investigated the effects of six different media with and without a nitrogen source and supplementation with nine organic compounds on the growth and astaxanthin accumulation of H. lacustris. The highest astaxanthin contents were observed in cultures of H. lacustris in Jaworski's medium (JM), with a level of 9.099 mg/L in JM with a nitrogen source supplemented with leucine (0.65 g/L) and of 20.484 mg/L in JM without a nitrogen source supplemented with sodium glutamate (0.325 g/L). Six of the nine organic compounds examined (leucine, lysine, alanine, sodium glutamate, glutamine, and cellulose) enhanced the production of astaxanthin in H. lacustris, while malic acid, benzoic acid, and maltose showed no beneficial effects.

Comparative Pharmacokinetic Study of Standard Astaxanthin and its Micellar Formulation in HealthyMale Volunteers.

Astaxanthin is a naturally occurring carotenoid with high anti-oxidant properties, but it is a very lipophilic compound with low oral bioavailability. This study was conducted to compare the pharmacokinetic parameters of a novel astaxanthin preparation based on micellar solubilization technology, NovaSOL® 400-mg capsules (Test product), and those of astaxanthin 400-mg capsules (reference product), after single oral dose administration to healthy male adults. A single oral dose (400 mg equivalent to 8 mg astaxanthin) of test and reference astaxanthin were administered with 240 mL of water to 12 volunteers according to crossover design, in two phases, with a washout period of 1week in between. Blood samples were collected at hourly intervals for the first 12 h, then at 24.0, 48.0, and 72.0 h after administration. Aliquots of plasma were centrifuged and the clear supernatant was injected into the high performance liquid chromatography-diode array detection (HPLC-DAD) system. Plasma concentration of astaxanthin versus time profiles were constructed, and the primary pharmacokinetic parameters, maximum concentration (Cmax), area under concentration time curve from time of administration (0) to time (t) [AUC0-t] or to infinity ∞, [AUC0-∞], half-life (T½) and time to reach Cmax (Tmax)were calculated. The test micellar astaxanthin reached a Cmax of 7.21 µg/ml after 3.67 h compared to only 3.86 µg/ml after 8.5 h for the reference native astaxanthin. Micellar formulation of astaxanthin is capable of producing a high concentration of astaxanthin in plasma in a shorter time, thereby expected to provide faster potential therapeutic efficacy.

Effects of Three Sources of Astaxanthin on the Growth, Coloration, and Antioxidant Capacity of Rainbow Trout (Oncorhynchus mykiss) during Long-Term Feeding

Astaxanthin is an important pigment for the rainbow trout Oncorhynchus mykiss. This study was conducted to investigate the effects of different sources of dietary astaxanthin on the growth, coloration, and antioxidant capacity of the commercial-sized O. mykiss during long-term feeding. Haematococcus pluvialis (HP), yeast Phaffia rhodozyma (PR), and synthetic astaxanthin (SA) were added to the basic feed (no astaxanthin, NA) to prepare the isonitrogenous and isolipidic experimental diets; the actual astaxanthin content values in the diets were 31.25, 32.96, and 31.50 mg/kg, respectively. Eighteen hundred O. mykiss, averaging 670 ± 20 g, were randomly divided into four groups and then fed with the experimental diet for four months. Dietary supplementation of P. rhodozyma and synthetic astaxanthin had no significant effects on the growth and tissue indexes of O. mykiss. In contrast, dietary supplementation with astaxanthin from H. pluvialis significantly increased the weight gain rate after four months of feeding. The fillet lightness of O. mykiss in the PR and SA was statistically lower than that in the NA and HP; the redness and astaxanthin content of fillet in the HP, PR, and SA groups were statistically higher than those in the NA. The total antioxidant capacity of the liver and serum in the HP was statistically higher than that in other diet groups, and a higher liver total superoxide dismutase activity was detected in the HP compared with the PR. Dietary supplementation of astaxanthin significantly increased the glutathione peroxidase activity in the liver and serum, and the highest serum glutathione peroxidase activity was detected in the HP, while dietary astaxanthin significantly decreased the malondialdehyde content in the liver and serum. Dietary supplementation of PR significantly increased the fillet ash content, while the highest fillet total lipid content was detected in the HP. Dietary astaxanthin significantly improved fillet redness and antioxidant capacity, among which H. pluvialis astaxanthin has greater effects on improving weight gain, antioxidant capacity, and fillet total lipid content.

Dietary Astaxanthin Can Promote the Growth and Motivate Lipid Metabolism by Improving Antioxidant Properties for Swimming Crab, Portunus trituberculatus.

This study aimed to assess the influence of varying dietary levels of astaxanthin (AST) on the growth, antioxidant capacity and lipid metabolism of juvenile swimming crabs. Six diets were formulated to contain different AST levels, and the analyzed concentration of AST in experimental diets were 0, 24.2, 45.8, 72.4, 94.2 and 195.0 mg kg-1, respectively. Juvenile swimming crabs (initial weight 8.20 ± 0.01 g) were fed these experimental diets for 56 days. The findings indicated that the color of the live crab shells and the cooked crab shells gradually became red with the increase of dietary AST levels. Dietary 24.2 mg kg-1 astaxanthin significantly improved the growth performance of swimming crab. the lowest activities of glutathione (GSH), total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and peroxidase (POD) were found in crabs fed without AST supplementation diet. Crabs fed diet without AST supplementation showed lower lipid content and the activity of fatty acid synthetase (FAS) in hepatopancreas than those fed diets with AST supplementation, however, lipid content in muscle and the activity of carnitine palmitoyl transferase (CPT) in hepatopancreas were not significantly affected by dietary AST levels. And it can be found in oil red O staining that dietary 24.2 and 45.8 mg kg-1 astaxanthin significantly promoted the lipid accumulation of hepatopancreas. Crabs fed diet with 195.0 mg kg-1 AST exhibited lower expression of ampk, foxo, pi3k, akt and nadph in hepatopancreas than those fed the other diets, however, the expression of genes related to antioxidant such as cMn-sod, gsh-px, cat, trx and gst in hepatopancreas significantly down-regulated with the increase of dietary AST levels. In conclusion, dietary 24.2 and 45.8 mg kg-1 astaxanthin significantly promoted the lipid accumulation of hepatopancreas and im-proved the antioxidant and immune capacity of hemolymph.

Astaxanthin suppresses the malignant behaviors of nasopharyngeal carcinoma cells by blocking PI3K/AKT and NF-κB pathways via miR-29a-3p

BackgroundAs a natural extraction, astaxanthin is gaining increasing attention because of its safety and anti-tumor properties. It has been reported to participate in the progression of various types of cancer such as gastric cancer and ovarian cancer. Nevertheless, the role of astaxanthin in nasopharyngeal carcinoma (NPC) has not been investigated.ObjectThe study aimed to explore the anticancer mechanism of astaxanthin in regulating NPC cell proliferation, cell cycle progression, apoptosis, migration, and invasion.MethodsHuman NPC cells (C666-1) were treated with different concentrations of astaxanthin (0, 1, 10, 20 mg/mL) followed by detection of cell viability. Then, C666-1 cell proliferation, apoptosis, cell cycle progression, invasion, and migration in response to 10 mg/mL astaxanthin, LY294002 (PI3K/AKT inhibitor) or parthenolide (PTL; NF-κB inhibitor) treatment were measured using cell counting kit-8 assay, colony forming assay, flow cytometry analyses, Transwell assay, and wound healing assay, respectively. Western blotting was performed to quantify protein levels of factors involved in PI3K/AKT and NF-κB signaling pathways, cell cycle phase markers (Cyclin D1, p21) and apoptotic markers (Bcl-2 and Bax).ResultsC666-1 cell proliferation, invasion, and migration were significantly suppressed by astaxanthin while cell apoptosis and cell cycle arrest at G1 phase were effectively enhanced in the context of 10 mg/mL astaxanthin. Protein levels of p-AKT, p-P65 and p-IκB levels were suppressed by astaxanthin treatment. After LY294002 or PTL treatment, the suppressive impact of astaxanthin on C666-1 cell process was strengthened, accompanied by the more obvious decrease in cell activity and cell colony number, more enhanced cell apoptosis and G1 phase arrest, and further inhibited cell migration and invasion. Moreover, the inhibitory effect of astaxanthin on Cyclin D1 and Bcl-2 protein levels as well as the promoting impact of astaxanthin on p21 and Bax were also amplified in combination with LY294002 or PTL treatment.ConclusionsAstaxanthin significantly suppresses NPC cell proliferation, cell cycle arrest, migration, invasion while promoting cell apoptosis by inactivating PI3K/AKT and NF-κB pathways. The study first reveals the anticancer role of astaxanthin in NPC, providing a potential candidate for NPC treatment.

Astaxanthin as an Anticancer Agent against Breast Cancer: An In Vivo and In Vitro Investigation.

This study aimed to investigate the antioxidant properties, cytotoxic activity, and apoptotic effects of astaxanthin (ASX) on genes and pathways involved in breast cancer in Balb/c mice models injected with the 4T1 cell line. ASX could inhibit some tumor progression by using in vivo and in vitro models. The effect of ASX on breast cancer was not fully understood till now. In an in vivo model, 4T1 cells-injected mice were administered with different concentrations of ASX (100 and 200 mg/kg), and histopathological evaluations were done using an optical microscope and the hematoxylin and eosin (H&E) staining. The real- time PCR investigated the expression levels of B-cell lymphoma 2-associated X (Bax), B-cell lymphoma 2 (Bcl-2), and Caspase 3 genes in mice treated with 100 and 200 mg/kg ASX. Also, the level of superoxide dismutase (SOD) and malondialdehyde (MDA) were examined in ASX-treated cancer mice. ASX (200 mg/kg) caused a significant reduction in the mitotic cell count of tumor tissues compared to ASX (100 mg/kg). The antiproliferative effects of different concentrations of ASX were shown based on the MTT results. The treatment of breast tumor mice with both concentrations of ASX, especially 200 mg/kg, elevated the expression of Caspase 3, Bax, and SOD enzyme levels and decreased Bcl-2 expression and MDA enzyme levels. ASX can be considered a promising alternative treatment for breast cancer.

Investigating the effect of astaxanthin on the survival rate of MCF-7 breast cancer cells by MTT method (cytotoxicity test)

Cancer is known as a very dangerous and incurable disease, with symptoms such as pain and disability. In recent years, changes in the way people live have increased the prevalence of breast cancer in different societies. This terrible disease has increased research in this field. Astaxanthin is one of the most famous natural carotenoids, which, due to its strong antioxidant activity, can prevent cardiovascular diseases, strengthen the body's immune system, and prevent cell ageing. In this study, the effect of astaxanthin on MCF-7 cancer cells was investigated. After culturing the cells in 96-well plates, they were treated with different concentrations of astaxanthin and then evaluated using the MTT method. The results showed that astaxanthin can inhibit cell growth and induce apoptosis, and this effect is enhanced by increasing the concentration of astaxanthin, so that at a concentration of 100 μM, the rate of apoptosis increased to 35%. Therefore, it can be concluded that astaxanthin may be used as a control treatment for cancer.

Establishing an astaxanthin-rich live feed strain of Pseudodiaptomus annandalei

This study aimed to establish an astaxanthin-rich strain of the calanoid copepod Pseudodiaptomus annandalei, through selective breeding based on RGB (red, green and blue) value, a parameter indicating color intensity. We evaluated the RGB value frequency distributions of the copepod populations, and selected individuals with the highest 10% and the lowest 10% RGB value over six generations. The RGB value, nauplii production, clutch interval and clutch number were assessed, and the genetic gain was calculated across generations (G0-G5). Two strains of copepods were selected and defined as dark body copepod strain (DBS) and light body copepod strain (LBS) at the end of experiment. Results revealed significantly lower RGB values (male: 121.5 ± 14.1; female: 108.8 ± 15) in the G5 DBS population compared to the G0 (male: 163.9 ± 13.1; female: 162.2 ± 14.6), with higher genetic gains of RGB values during G0 to G2. While DBS females exhibited longer clutch intervals in the G3 and G4, there was no significant difference in nauplii production between the two strains across all generations. Significantly higher astaxanthin content was found in the DBS copepods (0.04 μg/ ind.) compared to the LBS copepods (0.01 μg/ ind.) and the non-selective copepods (0.02 μg/ ind.) 20 months post selective breeding, validating the stability of the desired trait in the DBS strain. This study successfully established an astaxanthin-rich strain of P. annandalei, which provides implications for enhancing marine and brackish larviculture production.

The enhancement of astaxanthin production in Phaffia rhodozyma through a synergistic melatonin treatment and zinc finger transcription factor gene overexpression.

Astaxanthin has multiple physiological functions and is applied widely. The yeast Phaffia rhodozyma is an ideal source of microbial astaxanthin. However, the stress conditions beneficial for astaxanthin synthesis often inhibit cell growth, leading to low productivity of astaxanthin in this yeast. In this study, 1 mg/L melatonin (MT) could increase the biomass, astaxanthin content, and yield in P. rhodozyma by 21.9, 93.9, and 139.1%, reaching 6.9 g/L, 0.3 mg/g DCW, and 2.2 mg/L, respectively. An RNA-seq-based transcriptomic analysis showed that MT could disturb the transcriptomic profile of P. rhodozyma cell. Furthermore, differentially expressed gene (DEG) analysis show that the genes induced or inhibited significantly by MT were mainly involved in astaxanthin synthesis, metabolite metabolism, substrate transportation, anti-stress, signal transduction, and transcription factor. A mechanism of MT regulating astaxanthin synthesis was proposed in this study. The mechanism is that MT entering the cell interacts with components of various signaling pathways or directly regulates their transcription levels. The altered signals are then transmitted to the transcription factors, which can regulate the expressions of a series of downstream genes as the DEGs. A zinc finger transcription factor gene (ZFTF), one of the most upregulated DEGs, induced by MT was selected to be overexpressed in P. rhodozyma. It was found that the biomass and astaxanthin synthesis of the transformant were further increased compared with those in MT-treatment condition. Combining MT-treatment and ZFTF overexpression in P. rhodozyma, the biomass, astaxanthin content, and yield were 8.6 g/L, 0.6 mg/g DCW, and 4.8 mg/L and increased by 52.1, 233.3, and 399.7% than those in the WT strain under MT-free condition. In this study, the synthesis and regulation theory of astaxanthin is deepened, and an efficient dual strategy for industrial production of microbial astaxanthin is proposed.

ASTAXANTHIN SYNTHESIS IN SYNECHOCOCCUS PC7002: OPTIMIZATION AND PRODUCTSECRETIONTO CULTURE MEDIUM

Synechococcus sp. PCC7002 can produce theastaxanthin precursor β-carotene but not astaxanthin.Using a synthetic ketolase-and a synthetic hydroxylase-gene we modifiedSynechococcuscarotene metabolism to produce astaxanthin. The total cellular content of astaxanthin was further increased by over-expressing the intrinsic phytoene synthase. Besides a beneficial step in astaxanthin production our results indicate for some modifications in the suggestedprocess of carotenoid metabolism. In addition, we were expressing an E. coli ABC-transporter to export astaxanthinand decrease intracellular product accumulation. By this, the synthesis was increased further and significant amounts of astaxanthin can be recovered from culture medium without cell destruction.

Comparison of Body Characteristics, Carotenoid Composition, and Nutritional Quality of Chinese Mitten Crab (Eriocheir sinensis) with Different Hepatopancreas Redness.

In this study, we investigated the body characteristics, carotenoid composition, and nutritional quality of Eriocheir sinensis with different hepatopancreas redness (a*). We distributed the crabs into two groups based on the hepatopancreas a* values and compared their body characteristics, chroma, carotenoid composition, and protein, lipid, total sugar, amino acid, and fatty acid content via paired t-test. The results revealed that the relationships between hepatopancreas a* values and crab quality are sex specific. In female crabs, the differences in nutritional characteristics were evident mainly in the hepatopancreases and ovaries. In the redder hepatopancreases, the content of zeaxanthin and β-carotene increased, and the levels of C22:6n3 and C20:5n3 decreased (p < 0.05). In the ovaries, the content of astaxanthin, canthaxanthin, β-carotene, umami, and sweet amino acids were lower in the redder hepatopancreas crabs (p < 0.05). In male crabs, there were positive relationships between hepatopancreas a* and amino acid and fatty acid content. The content of leucine, arginine, and total umami amino acids in muscles and of unsaturated fatty acids and n-6 polyunsaturated fatty acids in hepatopancreases and testicles increased with increasing hepatopancreas a* values (p < 0.05). Therefore, the redder the hepatopancreas, the higher the nutritional quality of male crabs.