Search

The microalga Haematococcus pluvialis has diversified uses including formulation of fish foods. This microalga containing fish feed produces pigment in the flesh and enhances the growth and survival rate of the aquaculture organisms. The mass culture of H. pluvialis using commercial inorganic medium is expensive; therefore, in the present study, an alternate low-cost vegetable waste-based medium, the supernatant of the digested rotten wax gourd (Benincasa hispida), was used to culture the microalga. To assess the growth performance, H. pluvialis was cultured in 25% (T1), 50% (T2), and 75% (T3) of the digested rotten wax gourd supernatant (DRWGS) and in commercial Kosaric Medium (KM) (T4). The proximate composition of the rotten wax gourd, the physicochemical characteristics of the DRWGS, and the measured physicochemical parameters of the cultured media prepared using the DRWGS revealed the suitability of the rotten wax gourd for the growth of H. pluvialis. The growth of H. pluvialis in terms of cell density, mean daily division rate, optical density, dry cell weight, and chlorophyll-a was found highest in T4, followed by T3, T2, and T1, respectively. Importantly, the growth parameters and the protein and lipid content of the microalga H. pluvialis exhibited no significant (p > 0.05) difference between T4 (KM) and T3 (75% DRWGS). The findings of the present study revealed that the digested rotten wax gourd supernatant can be utilized for the mass culture of the microalga H. pluvialis, and the higher concentration up to a certain level of the supernatant is good for the culture. The cost of production of a certain amount of the commercial medium KM is about two times higher than the production of the same amount of the 75% DRWGS medium. This low-cost DRWGS can be used in mass production of the microalga H. pluvialis which has a high potential in rearing zooplankton and fish larvae in hatcheries. Fish larvae grown on live feeds (microalgae and zooplankton) normally have high growth and survival rate. Adequate supply of high-quality fish larvae to the farmers in due time is the prerequisite for sustainable enhanced aquaculture. [ABSTRACT FROM AUTHOR]

For biofuels and nutraceuticals, the green microalga Haematococcus pluvialis (Chlorophyceae) is a prospective source of biomass and lipids. This study examined how biomass production and lipid accumulation were affected by temperature (10 °C, 20 °C, and 30 °C) and potassium nitrate (KNO₃) concentrations (0.41 g/L, 0.31 g/L, 0.21 g/L, 0.10 g/L, and 0). The findings showed that the largest biomass (0.665 ± 0.200 g/L) was produced at a potassium nitrate concentration of 0.21 g/L at 20 °C, whereas the highest lipid content (46.31 ± 0.026% dry weight) was produced at a temperature without nitrate. Notably, a balanced result was obtained with a modest nitrate content (0.10 g/L) at 20 °C, yielding significant biomass (0.560 ± 0.136 g/L) and lipids (40.30 ± 0.012% dry weight). These results highlight how crucial it is to optimize cultivation settings in order to increase H. pluvialis's dual productivity, offering important new information for its industrial-scale use. By adjusting growing conditions, this research helps meet the need for renewable resources worldwide by promoting the production of high-value bioproducts and sustainable, commercially viable algae-based biofuels. [ABSTRACT FROM AUTHOR]

This study examined the effects of Haematococcus pluvialis on the growth performance, innate immunity, and gut microbiota of Litopenaeus vannamei under different water temperature conditions. Feeding regimens included a 20% fishmeal diet (control), a low-fish meal (LFM) diet with 10% fishmeal and an LFM diet supplemented with 0.03% H. pluvialis. These diets were administered to six groups of L. vannamei at normal (30°C) (NT) and low (20°C) (LT) temperatures (NT_C, NT_LFM, NT_LFM_HP, LT_C, LT_LFM, and LT_LFM_HP) over 8 weeks. The weight gain rate of L. vannamei in group NT_LFM_HP was significantly higher compared to group NT_LFM. Astaxanthin levels and body pigmentation intensity in L. vannamei were significantly increased in the NT_LFM_HP and LT_LFM_HP groups. Moreover, hepatopancreatic antioxidant capacities, such as superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC), were lower in normal-temperature groups compared to the low-temperature groups. Nevertheless, antioxidant capacity was significantly higher in both the NT_LFM_HP and LT_LFM_HP groups compared to the control group. Meanwhile, the expression levels of antioxidants were significantly higher at lower temperatures compared to higher temperatures, with the NT_LFM_HP and LT_LFM_HP groups exhibiting the highest expression levels. Additionally, the mRNA levels of genes associated with the Toll and IMD pathways indicated immunoregulatory effects in the organism. The expression levels of immune genes were significantly higher at lower temperatures, especially in the NT_LFM_HP and LT_LFM_HP groups compared to the control groups. Notably, significant differences in gut microbial composition were observed in the NT_LFM_HP group compared to other groups, with variations influenced by temperature and fishmeal content. Specifically, Vibrionaceae abundance was significantly lower in the LT_LFM_HP group compared to the control group. The results also revealed that the abundance of Actinomarinales was significantly higher in low-temperature groups, with the LT_LFM_HP group displaying the greatest increase. Overall, these findings suggest that L. vannamei may be susceptible to reduced fishmeal levels, potentially impacting growth and immune function. Furthermore, H. pluvialis supplementation may assist L. vannamei in acclimating to prolonged low-temperature conditions. [ABSTRACT FROM AUTHOR]

Astaxanthin, a natural ketone carotenoid, is among the environmentally friendly antioxidants and immunopotentiators. A 60-day feeding experiment was proceeded to assess the feasibility of astaxanthin-rich Haematococcus pluvialis as a growth promoter, antioxidant, and immunostimulant in the hybrid red tilapia (Oreochromis niloticus x O. mossambicus). Experimental diets containing grade amounts of Haematococcus pluvialis powder (0, 0.5, 1.0, and 1.5 g kg−1 feed) were formulated to be fed to red tilapia (Initial weight 27 ± 0.5 g) and designated as control, HP0.5, HP1, and HP1.5, respectively. The results indicated that the HP1 and HP1.5 promoted growth performance by decreasing FCR and increasing FBW, WG, WGR, and SGR confirmed by better intestinal morphology. Moreover, the HP1 and HP1.5 diets improved non-specific immunity via enhancing phagocytic activity, IgG and IgM contents, and nitric oxide, while decreasing MPO values compared to the control. Additionally, the H. pluvialis diets boosted antioxidant ability through elevating serum SOD and GSH activities, unlike the control group. The HP0.5, HP1, and HP1.5 diets also exerted hepatoprotective effects via histological sections as well as, suppressing liver enzymes (ALT, AST, ALP, and GGT) and reducing serum TG and cholesterol contents confirmed our data. Besides, a notable decrease in the serum levels of IFN-γ and IL-4 along with hepatic mRNA levels of TNF-α, IL-1β, IL-8, and caspase-3 with the increasing doses of H. pluvialis. These results proposed that a diet supplemented with 1 and 1.5 g kg−1H. pluvialis is exhorted to augment the growth performance, hepatoprotection, antioxidant capacity, immunity, and anti-inflammatory response of red tilapia. [ABSTRACT FROM AUTHOR]

The efficient production of the high-value antioxidant astaxanthin is crucial for economically viable biorefinement of the green microalga Haematococcus lacustris. In this study, we investigated the impact of reduced atmospheric pressure (0.8–0.2 bar) on cell morphology and astaxanthin biosynthesis in H. lacustris over 72 h. Astaxanthin content in microalgal cells subjected to depressurization at an optimal pressure of 0.6 bar for 48 h increased by 26.9 and 13.2% compared with that in initial cells and untreated controls, respectively. Furthermore, depressurization led to increased cell size and elevated levels of canthaxanthin (a major astaxanthin intermediate) and total fatty acids. Depressurized H. lacustris cells maintained high cell viability rates, ranging from 96.0 to 97.5% for 72 h. However, excessive or prolonged pressure reduction, particularly beyond 60 h or at 0.2–0.4 bar, hindered the ability of microalgae to synthesize astaxanthin. Astaxanthin accumulation under reduced pressure is likely associated with the formation of reactive oxygen species, which serve as signaling biomolecules triggering astaxanthin biosynthesis. These findings provide valuable insights into the biology and ketocarotenoid biosynthesis of microalgae under different hydraulic pressure conditions, as well as the responses of other biological components of life support systems required in low-pressure lunar and Martian environments. [ABSTRACT FROM AUTHOR]

Haematococcus pluvialis is a green microalga of commercial interests due to its ability to produce a high value ketocarotenoid, astaxanthin. As a non-model species that lacks a well annotated genome, omics analyses such as transcriptomics and proteomics analysis have often been used together with physiological and biochemical analysis to explore pathways of interest. However, interpretation of these datasets remains challenging. In this work, TMT-based proteomics and phosphoproteomics analyses were conducted on Haematococcus cells grown under favorable conditions (green stage biomass) and high-light stress conditions (red stage biomass). Phosphoproteins were enriched using titanium dioxide before LC–MS/MS analysis. Our proteomics and phosphoproteomics analyses identified 1394 proteins and 569 phosphosites on 366 phosphoproteins, respectively. Of these, 1315 proteins and 396 phosphosites on 314 phosphoproteins were quantifiable, among which 370 proteins and 121 phosphosites on 94 phosphoproteins were differentially expressed. Using an improved analysis pipeline that combines Blast2GO, KEGG, and DAVID to analyze differentially expressed proteins and phosphoproteins, total identified proteins increased from 255 to 322 and total identified phosphoproteins increased from 59 to 70, which were 26.28% and 18.64%, respectively, higher than with the UniProt analysis alone. Using this pipeline, a previously uncharacterized protein and phosphoprotein were identified as an ATPase subunit B and a phosphofructokinase, respectively, and further confirmed with translated genomic and transcriptomic data. This work provides an example of phosphoproteomics analysis in H. pluvialis, while the proteomics and phosphoproteomics analysis pipelines described here may be useful to analyze omics data from other non-model algal species. [ABSTRACT FROM AUTHOR]

Background: Haematococcus pluvialis, a green microalga, is a rich source of natural astaxanthin and a potent antioxidant with high commercial value. This study investigates the biological characteristics and potential of H. pluvialis HB isolated from Hoa Binh, Vietnam, for growth and astaxanthin accumulation using a two-phase culture method. Methods: H. pluvialis HB was cultured in a C/RM medium at 25 °C, and morphological characteristics were examined. NMR spectroscopy was used to determine the structure of the astaxanthin, which was extracted using the Soxhlet method. Results: After 22 days, the highest cell density (4.96 × 106 cells mL−1) was achieved under optimized light and ultraviolet conditions. Nutrient deprivation followed by bicarbonate supplementation resulted in a maximal astaxanthin accumulation of 48.8 mg g−1 dry cell weight within two days. The extracted astaxanthin demonstrated potent antioxidant activity (IC50: 3.74 mg mL−1) compared to ascorbic acid (IC50: 18.53 µg mL−1) and exhibited strong acetylcholinesterase inhibition (IC50: 297.99 µg mL−1). It also showed neuroprotective effects against H2O2 and amyloid beta-induced neurotoxicity in C6 cells. Conclusions: This study highlights H. pluvialis HB as a promising source for large-scale astaxanthin production with potential applications in neuroprotective health products. [ABSTRACT FROM AUTHOR]

Han-Sol You,1,* Young-Sun Jang,2,* Anbazhagan Sathiyaseelan,1 Su-Ji Ryu,1 Ha-Yeon Lee,1 Jong-Suep Baek1,3 1Department of Bio-Health Convergence, Kangwon National University, Chuncheon, 24341, Republic of Korea; 2College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea; 3BeNatureBioLab, Chuncheon, 24206, Republic of Korea*These authors contributed equally to this workCorrespondence: Jong-Suep Baek, Email jsbaek@kangwon.ac.krPurpose: Multi-walled carbon nanotubes (MWCNTs) were used as carriers for silver nanoparticles (AgNPs). In this process, MWCNTs were coated with mesoporous silica (MWCNT-Silica) for uniform and regular loading of AgNPs on the MWCNTs. In addition, astaxanthin (AST) extract was used as a reducing agent for silver ions to enhance the antioxidant, antibiofilm, and anticancer activities of AgNPs. In this process, AST was extracted from Haematococcus pluvialis (H. pluvialis) and processed by hot melt extrusion (HME) to enhance the AST content of H. pluvialis. AST has strong antioxidative properties, which leads to anticancer activity. In addition, AgNPs are well known for their strong antibacterial properties. The antibiofilm and anticancer effects were studied comprehensively by loading the AST AgNPs onto MWCNT-Silica.Methods: AgNPs-loaded MWCNT-silica (MWCNT-Ag) was prepared through the binding reaction of TSD and silanol groups and the aggregation interaction of Ag and TSD. To enhance the antioxidant, antibiofilm, and anticancer activities of AgNPs, HME-treated H. pluvialis extract (HME-AST) was used as a reducing solution of silver ions. The increased AST content of HME-AST was confirmed by high-performance liquid chromatography (HPLC) analysis, and the total phenol and flavonoid content analysis confirmed that HME enhanced the active components of H. pluvialis. The antibiofilm activity of MWCNT-AST was investigated by biofilm inhibition and destruction test, SEM, and CLSM analysis, and the anticancer activity was investigated by WST assay, fluorescent staining analysis, and flow cytometry analysis.Results: MWCNT-AST showed higher antioxidant activity and antibiofilm activity than MWCNT-Ag against E. coli, S. aureus, and methicillin-resistant S. aureus (MRSA). MWCNT-AST showed higher anticancer activity against breast cancer cells (MDA-MB-231) than MWCNT-Ag, and lower toxicity in normal cells HaCaT and NIH3T3.Conclusion: MWCNT-AST exhibits higher antioxidant, antibiofilm, and anticancer activities than MWCNT-Ag, and exhibits lower toxicity to normal cells. Keywords: Haematococcus pluvialis, astaxanthin, silver nanoparticles, multi-walled carbon nanotubes, anticancer, antibiofilm, multi-drug resistance

The slow growth and complex life cycle of Haematococcus lacustris pose significant challenges for cost-effective astaxanthin production. This study explores the use of microfluidic collision treatment to stimulate the germination of dormant seed cysts, thereby improving photosynthetic cell growth and astaxanthin productivity in H. lacustris cultivated in well plate and flask cultures. The flow rate (1.0–3.0 mL/min) and the number of T-junction loops (3–30) were optimized in the microfluidic device. Under optimal conditions (a flow rate of 2.0 mL/min with 10 loops), the total cell number density in well plate cultures increased by 44.5% compared to untreated controls, reaching 28.9 ± 2.0 × 104 cells/mL after 72 h. In flask cultures, treated cysts showed a 21% increase in astaxanthin productivity after 30 d, reaching 0.95 mg/L/d, due to higher biomass concentrations, while the astaxanthin content per cell remained constant. However, excessive physical collision stress at higher flow rates and loop numbers resulted in reduced cell viability and cell damage. These findings suggest that carefully controlled cyst mechanostimulation can be an effective and environmentally friendly strategy for Haematococcus biorefining, enabling the production of multiple bioactive products. [ABSTRACT FROM AUTHOR]

The increasing interest in hydrogel matrices and their diverse applications has fueled extensive research. However, single‐component gels have a limited adjustable performance range, and multi‐component gels raise concerns about biological safety, hindering their widespread use. This study focuses on harnessing high‐speed shearing and ultrasound‐assisted methods to incorporate active natural Haematococcus pluvialis (HP), creating novel composite hydrogels in conjunction with biological macromolecule gellan gum, and eliminating the need for structural modifications or chemical crosslinking. Rich astaxanthin, proteins, polysaccharides, and other components in HP can fill and promote the formation of a unified functional network. The study aims to explore the potential of HP as a rheology regulator and investigate its impact on the rheological properties of the gels. Various rheological models, including Power‐Law, Herschel–Bulkley, and Arrhenius, were employed for comparative analysis. This pioneering report on gellan/HP hydrogels holds significant importance as they exhibit optimized elasticity, thermal stability, enhanced injectability, and self‐recovery, making them suitable for a wide range of applications in specialized medical food and biomedicine. [ABSTRACT FROM AUTHOR]

Haematococcus pluvialis contains valuable bioactive compounds, including astaxanthin, proteins, and fatty acids. Astaxanthin is known for its various health benefits, such as preserving the redox balance and reducing inflammation. However, its low stability and poor water solubility present challenges for various applications. Hot-melt extrusion (HME) technology enhances the aqueous solubility of H. pluvialis extracts, increasing the usable astaxanthin content through nanoencapsulation (HME-DDS-applied extracts, ASX-60F and ASX-100F). This study compared the effects of HME-DDS-derived extracts (ASX-60F and ASX-100F) and the non-applied extract (ASX-C) under inflammatory and oxidative stress conditions. In animal models of sepsis, 60F and 100F treatment exhibited higher survival rates and a lower expression of pro-inflammatory biomarkers compared to those treated with C. In lipopolysaccharide-stimulated RAW 264.7 macrophages, nitric oxide (NO) production and the expression of pro-inflammatory mediators such as cyclooxygenase-2 and inducible NO synthase were reduced by 60F or 100F treatments via ERK/p-38 mitogen-activated protein kinase (MAPK) signaling. Moreover, 60F or 100F inhibited reactive oxygen species production regulated by nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling. Collectively, these findings suggest that HME-DDS-derived H. pluvialis extracts exert anti-inflammatory and antioxidant effects by inhibiting MAPK phosphorylation and activating Nrf2/HO-1 expression. [ABSTRACT FROM AUTHOR]

The cultivation of Haematococcus pluvialis is pivotal in the biotechnological production of astaxanthin, a powerful antioxidant with extensive applications in the nutraceutical, pharmaceutical, and aquaculture industries. Astaxanthin accumulation is known to be enhanced under stress conditions. Recent advancements have highlighted the efficacy of mixotrophic cultivation in enhancing both biomass production and carotenoid accumulation. The aim of this work is to evaluate the effect of mixotrophic conditions induced by BWW on biomass growth and carotenoid accumulation. To this aim, experiments carried out with different light intensities and cultivation time were specifically designed. This study displays the effective production of carotenoids by H. pluvialis using brewery wastewater (BWW) as an organic source able to sustain mixotrophic conditions. Various ratios of BWW were combined with the BG11 medium. When H. pluvialis was cultivated solely in BWW or in the control medium BG11, both the biomass and astaxanthin contents were reduced compared to the higher values obtained in their blended mixtures. In particular, the BWW-BG11 1:1 system exhibited the highest values of biomass (5.46 g L−1) and astaxanthin content (2.32%) compared to both undiluted BWW (3.34 g L−1 and 1.95%) and the control BG11 (3.65 g L−1 and 0.65%), respectively. BWW significantly boosted the growth rate and metabolic activity of H. pluvialis. This dual approach not only accelerates biomass accumulation but also enhances the synthesis of carotenoids, particularly astaxanthin. The integration of mixotrophic strategies into H. pluvialis cultivation systems presents a promising avenue for optimizing the commercial production of astaxanthin, ensuring higher yields and cost-effectiveness. [ABSTRACT FROM AUTHOR]

Microalgae are photosynthetic organisms that are described as an abundant source of numerous bio compounds of commercial value, and using this green treasure as a vital alternative to expensive synthetic hormones via biotechnological technique is the main objective of research. Murashige and Skoog medium supplemented with crude extract of Microcystis aeruginosa and Haematococcus pluvialis, separately was used to study its effect on Cynanchum acutum L., which is an important wild medicinal plant. Results revealed that all growth parameters have been affected where, the greatest shoot length (5.90 ± 0.45) has been reached with 4 mg/L of Microcystis aeruginosa extract, while the highest shoot number (7.50 ± 0.30) and leaf number (16.0 ± 0.59) were with 12 mg/L of Microcystis aeruginosa extract. Conversely, the maximum shoot length (12.5 ± 0.44) was reached with 2 mg/L of Haematococcus pluvialis extract, while the highest shoot number (6.00 ± 0.36) and leaf number per shootlet (22.0 ± 0.92) were with 5 mg/L of Haematococcus pluvialis extract. Biochemical analysis for algae and plant extracts conducted using HPLC proved the presence of phytohormones (zeatin, gibberellin, and kinetin) in algal extracts and nineteen important phenolic and flavonoid substances in plant extracts. The novelty of this study is to use algae as a natural source of growth regulators to achieve an economic benefit in addition to propagating Cynanchum acutum L. and increasing its important pharmaceutical products. [ABSTRACT FROM AUTHOR]

The consumption of fatty acids offers significant health benefits; however, they are prone to degradation by environmental factors. One method to preserve these fatty acids is the addition of synthetic antioxidants. This study focuses on the determination of peroxide and MDA formation rates at temperatures of 25 °C, 45 °C, and 65 °C. The oxidative stability of cold-pressed avocado oil was evaluated using pure astaxanthin, TBHQ, and H. pluvialis extract at concentrations of 100, 500, and 1000 ppm. Kinetic models and thermodynamic analysis were applied to determine the oxidation rate and compare the antioxidant effects of H. pluvialis extract with astaxanthin and TBHQ. The Arrhenius model was used to estimate activation energy (Ea), enthalpy, entropy, and free energy. Avocado oil with 500 ppm of H. pluvialis extract showed antioxidant effects comparable to TBHQ and pure astaxanthin. The activation energy of plain avocado oil was 40.47 kJ mol−1, while with H. pluvialis extract, it was 54.35 kJ mol−1. These findings suggest that H. pluvialis extract offers effective antioxidant properties and could serve as a natural alternative to synthetic antioxidants in food applications, despite the limitations of unprotected astaxanthin. [ABSTRACT FROM AUTHOR]

Experiments are increasingly performed in vitro; therefore, cell culture technology is essential for scientific progress. Fetal bovine serum (FBS) is a key cell culture supplement providing growth factors, amino acids, and hormones. However, FBS is not readily available on the market, has contamination risks, and has ethical concerns. This study aimed to investigate Haematococcus pluvialis extracts (HE) as a potential substitute for FBS. Therefore, we assessed the effects of HE on cell maintenance, growth, and cycle progression in human lung fibroblasts (MRC-5). Cell progression and monosaccharide, fatty acid, and free amino acid compositions were analyzed using cell cycle analysis, bio-liquid chromatography, gas chromatography, and high-performance liquid chromatography, respectively. The results of nutritional profiles showed that the extracts contained essential amino acids required for synthesizing non-essential amino acids and other metabolic intermediates. Furthermore, most of the components present in HE were consistent with those found in FBS. HE enhanced cell viability and regulated cell cycle phases. Additionally, the interaction between growth factor cocktails and HE significantly improved cell viability, promoted cell cycle progression, and activated key cell cycle regulators, such as cyclin A and cyclin-dependent kinases 1 (CDK1). Our findings suggest that HE have considerable potential to substitute FBS in MRC-5 cell cultures and have functional and ethical advantages. [ABSTRACT FROM AUTHOR]

Astaxanthin is a naturally occurring xanthophyll with powerful: antioxidant, antitumor, and antibacterial properties that are widely employed in food, feed, medicinal and nutraceutical industries. Currently, chemical synthesis dominates the world's astaxanthin market, but the increasing demand for natural products is shifting the market for natural astaxanthin. Haematococcus pluvialis (H. pluvialis) is the factory source of natural astaxanthin when grown in optimal conditions. Currently, various strategies for the production of astaxanthin have been proposed or are being developed in order to meet its market demand. This up-to-date review scrutinized the current approaches or strategies that aim to increase astaxanthin yield from H. pluvialis. We have emphasized the genetic and environmental parameters that increase astaxanthin yield. We also looked at the transcriptomic dynamics caused by environmental factors (phytohormones induction, light, salt, temperature, and nutrient starvation) on astaxanthin synthesizing genes and other metabolic changes. Genetic engineering and culture optimization (environmental factors) are effective approaches to producing more astaxanthin for commercial purposes. Genetic engineering, in particular, is accurate, specific, potent, and safer than conventional random mutagenesis approaches. New technologies, such as CRISPR-Cas9 coupled with omics and emerging computational tools, may be the principal strategies in the future to attain strains that can produce more astaxanthin. This review provides accessible data on the strategies to increase astaxanthin accumulation natively. Also, this review can be a starting point for new scholars interested in H. pluvialis research. [ABSTRACT FROM AUTHOR]

This study examined the effects of Haematococcus pluvialis on the growth performance, innate immunity, and gut microbiota of Litopenaeus vannamei under different water temperature conditions. Feeding regimens included a 20% fishmeal diet (control), a low-fish meal (LFM) diet with 10% fishmeal and an LFM diet supplemented with 0.03% H. pluvialis. These diets were administered to six groups of L. vannamei at normal (30°C) (NT) and low (20°C) (LT) temperatures (NT_C, NT_LFM, NT_LFM_HP, LT_C, LT_LFM, and LT_LFM_HP) over 8 weeks. The weight gain rate of L. vannamei in group NT_LFM_HP was significantly higher compared to group NT_LFM. Astaxanthin levels and body pigmentation intensity in L. vannamei were significantly increased in the NT_LFM_HP and LT_LFM_HP groups. Moreover, hepatopancreatic antioxidant capacities, such as superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC), were lower in normal-temperature groups compared to the low-temperature groups. Nevertheless, antioxidant capacity was significantly higher in both the NT_LFM_HP and LT_LFM_HP groups compared to the control group. Meanwhile, the expression levels of antioxidants were significantly higher at lower temperatures compared to higher temperatures, with the NT_LFM_HP and LT_LFM_HP groups exhibiting the highest expression levels. Additionally, the mRNA levels of genes associated with the Toll and IMD pathways indicated immunoregulatory effects in the organism. The expression levels of immune genes were significantly higher at lower temperatures, especially in the NT_LFM_HP and LT_LFM_HP groups compared to the control groups. Notably, significant differences in gut microbial composition were observed in the NT_LFM_HP group compared to other groups, with variations influenced by temperature and fishmeal content. Specifically, Vibrionaceae abundance was significantly lower in the LT_LFM_HP group compared to the control group. The results also revealed that the abundance of Actinomarinales was significantly higher in low-temperature groups, with the LT_LFM_HP group displaying the greatest increase. Overall, these findings suggest that L. vannamei may be susceptible to reduced fishmeal levels, potentially impacting growth and immune function. Furthermore, H. pluvialis supplementation may assist L. vannamei in acclimating to prolonged low-temperature conditions.

Abstract Astaxanthin biosynthesis in Haematococcus pluvialis is driven by energy. However, the effect of the flagella-mediated energy-consuming movement process on astaxanthin accumulation has not been well studied. In this study, the profiles of astaxanthin and NADPH contents in combination with the photosynthetic parameters with or without flagella enabled by pH shock were characterized. The results demonstrated that there was no significant alteration in cell morphology, with the exception of the loss of flagella observed in the pH shock treatment group. In contrast, the astaxanthin content in the flagella removal groups was 62.9%, 62.8% and 91.1% higher than that of the control at 4, 8 and 12 h, respectively. Simultaneously, the increased Y(II) and decreased Y(NO) suggest that cells lacking the flagellar movement process may allocate more energy towards astaxanthin biosynthesis. This finding was verified by NADPH analysis, which revealed higher levels in flagella removal cells. These results provide preliminary insights into the underlying mechanism of astaxanthin accumulation enabled by energy reassignment in movement-lacking cells.

Haematococcus pluvialis residue powder, which has been extracted with astaxanthin, was used as the raw material to prepare Haematococcus pluvialis protein by alkaline extraction and acid precipitation method. The protein structure of Haematococcus pluvialis was characterized, and the effects of pH and ion strength on the functional characteristics of Haematococcus pluvialis protein were studied. The results showed that the isoelectric point of Haematococcus pluvialis protein was 4.2. The molecular weight of the subunit was around 14.4, 18.4 and 38 kDa, respectively and the content of α-helix, β-fold, β-corner and disordered structure in the secondary structure was 14.86%, 18.47%, 40.3% and 26.37%, respectively. It contained 7 kinds of essential amino acids required by the human body, accounting for 36.38% of the total amino acid content. Microscopic observation showed that the protein of Haematococcus pluvialis was rod-shaped and sheet-like, with a rough and porous surface. With the increase of pH, the solubility, water absorption, emulsion capability, foam stability and foam stability of the protein of Haematococcus pluvialis increased first and then decreased, while the emulsification stability showed the opposite trend. With the increase of NaCl concentration, the foam capability, foam stability, emulsion capability and emulsification stability of the protein of Haematococcus pluvialis increased first and then decreased, while the solubility showed a trend of first decreasing, then increasing, and then decreasing again.

Abstract 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.

Astaxanthin biosynthesis in Haematococcus pluvialis is driven by energy. However, the effect of the flagella-mediated energy-consuming movement process on astaxanthin accumulation has not been well studied. In this study, the profiles of astaxanthin and NADPH contents in combination with the photosynthetic parameters with or without flagella enabled by pH shock were characterized. The results demonstrated that there was no significant alteration in cell morphology, with the exception of the loss of flagella observed in the pH shock treatment group. In contrast, the astaxanthin content in the flagella removal groups was 62.9%, 62.8% and 91.1% higher than that of the control at 4, 8 and 12 h, respectively. Simultaneously, the increased Y(II) and decreased Y(NO) suggest that cells lacking the flagellar movement process may allocate more energy towards astaxanthin biosynthesis. This finding was verified by NADPH analysis, which revealed higher levels in flagella removal cells. These results provide preliminary insights into the underlying mechanism of astaxanthin accumulation enabled by energy reassignment in movement-lacking cells. [ABSTRACT FROM AUTHOR]

Astaxanthin has 550 times more antioxidant activity than vitamin E, so it can scavenge free radicals in vivo and improve body immunity. However, the poor stability of astaxanthin becomes a bottleneck problem that limits its application. Herein, Haematococcus pluvialis (H. pluvialis) as a raw material was used to extract astaxanthin, and the optimal extraction conditions included the extraction solvent (EA:EtOH = 1:6, v/v), extraction temperature (60 °C), and extraction time (70 min). The extracted astaxanthin was then loaded using lecithin to form corresponding liposomes via the ethanol injection method. The results showed that the particle size and zeta potential of the prepared liposomes were 105.8 ± 1.2 nm and −38.0 ± 1.7 mV, respectively, and the encapsulation efficiency of astaxanthin in liposomes was 88.83%. More importantly, the stability of astaxanthin was significantly improved after being embedded in the prepared liposomes. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Science & Technology of Cereals, Oils & Foods is the property of Science & Technology of Cereals, Oils & Foods Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

Introduction: Astaxanthin is a xanthophyll carotenoid derived from the green algae Haematococcus pluvialis, which is a potential candidate for ulcer therapy because of its antioxidant and anti-inflammatory effects. The purpose of this research was to explore the anti-inflammatory potency of 0,5%, and 1% astaxanthin (Haematococcus pluvialis) gel to oral traumatic ulcers. Materials and methods: Twenty Wistar rats with traumatic ulcer models were divided randomly into 4 groups based on the administration of topical therapy for 3 and 7 days. Groups were: Base Gel Group (BGG) as negative control, Hyaluronic acid 0,2% Gel Group (HGG), Astaxanthin gel 0,5% Group (AGG1), Astaxanthin gel 1% Group (AGG2). Neutrophils, macrophages, and fibroblasts were examined by hematoxylin-eosin (HE) staining, under the light microscope (400x magnification). Data were analyzed by Univariate analysis One way-ANOVA with post hoc LSD and Kruskal-walis with post hoc Mann-Whitney. Results: TThere were signification differences in the number of neutrophils, macrophages, fibroblasts, and collagen density (p<0,05) between all groups on days 3 and 7. Conclusion: Astaxanthin gel 0,5%, and 1% have the therapeutic effect in increasing the number of neutrophils, macrophages, and fibroblast on day 3 so did fibroblast and collagen density on day 7 of the healing process of oral traumatic ulcer. The most effective dose was on astaxanthin gel 0,5%. [ABSTRACT FROM AUTHOR]

Microalgae are the preferred species for producing astaxanthin because they pose a low toxicity risk than chemical synthesis. Astaxanthin has multiple health benefits and is being used in: medicines, nutraceuticals, cosmetics, and functional foods. Haematococcus pluvialis is a model microalga for astaxanthin biosynthesis; however, its natural astaxanthin content is low. Therefore, it is necessary to develop methods to improve the biosynthesis of astaxanthin to meet industrial demands, making its commercialization cost-effective. Several strategies related to cultivation conditions are employed to enhance the biosynthesis of astaxanthin in H. pluvialis. However, the mechanism of its regulation by transcription factors is unknown. For the first time, this study critically reviewed the studies on identifying transcription factors, progress in H. pluvialis genetic transformation, and use of phytohormones that increase the gene expression related to astaxanthin biosynthesis. In addition, we propose future approaches, including (i) Cloning and characterization of transcription factors, (ii) Transcriptional engineering through overexpression of positive regulators or downregulation/silencing of negative regulators, (iii) Gene editing for enrichment or deletion of transcription factors binding sites, (iv) Hormonal modulation of transcription factors. This review provides considerable knowledge about the molecular regulation of astaxanthin biosynthesis and the existing research gap. Besides, it provides the basis for transcription factors mediated metabolic engineering of astaxanthin biosynthesis in H. pluvialis. [ABSTRACT FROM AUTHOR]

The Chinese mitten crab (Eriocheir sinensis) is bred extensively in Eastern and Northern China and faces a series of problems such as frequent diseases, germplasm degradation, and declining benefits, which have appeared to seriously affect the sustainable development of the cultivation industry. Haematococcus pluvialis, a type of unicellular green algae, have been proven to be the suitable dietary supplementation in crustacean feeds. After 14 days of feeding with 5% dietary supplementation with Haematococcus pluvialis powder, the growth, antioxidantase activities, and gut microbiota of E. sinensis were analyzed. The results indicated that H. pluvialis powder could significantly improve growth indicators including weight gain rate (WGR) and specific growth rate (SGR) of E. sinensis (p < 0.05). The levels of superoxide dismutase (SOD) and catalase (CAT) declined, while that of phenoloxidase (PO) kept rising under the treatment of H. pluvialis powder. Moreover, alkaline phosphatase (AKP) activity dropped initially and then increased. No significant differences in the Simpson index and Chao1 index in the control and H. pluvialis powder treatment were observed (p > 0.05). Although the dominant microbiota in the crab gut were not affected significantly by H. pluvialis powder, significant differences in the relative abundance of the dominant phyla between the control and H. pluvialis powder treatment groups were observed (p < 0.05). Furthermore, the relative abundance of Firmicutes and Candidatus_Bacilloplasma, which play an important role in the life activities of E. sinensis, were significantly higher in the group treated by H. pluvialis powder than in the control (p < 0.05). Therefore, the H. pluvialis powder could be potentially used not only as a rapid fattening regulator, but also to improve the immunity and metabolic capacity of E. sinensis. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) are nano-sized particles involved in intercellular communications that intrinsically possess many attributes as a modern drug delivery platform. Haematococcus pluvialis-derived EVs (HpEVs) can be potentially exploited as a high-value-added bioproduct during astaxanthin production. The encapsulation of HpEV cargo is a crucial key for the determination of their biological functions and therapeutic potentials. However, little is known about the composition of HpEVs, limiting insights into their biological properties and application characteristics. This study examined the protein composition of HpEVs from three growth phases of H. pluvialis grown under high light (350 µmol·m−2·s−1) and sodium acetate (45 mM) stresses. A total of 2038 proteins were identified, the majority of which were associated with biological processes including signal transduction, cell proliferation, cell metabolism, and the cell response to stress. Comparative analysis indicated that H. pluvialis cells sort variant proteins into HpEVs at different physiological states. It was revealed that HpEVs from the early growth stage of H. pluvialis contain more proteins associated with cellular functions involved in primary metabolite, cell division, and cellular energy metabolism, while HpEVs from the late growth stage of H. pluvialis were enriched in proteins involved in cell wall synthesis and secondary metabolism. This is the first study to report and compare the protein composition of HpEVs from different growth stages of H. pluvialis, providing important information on the development and production of functional microalgal-derived EVs. [ABSTRACT FROM AUTHOR]