Astaxanthin Production Research Articles

The Discrepancy of Fatty Acid Composition of Astaxanthin Esters and Total Fatty Acids in Photoautotrophic and Heterotrophic Chlorella zofingiensis

Abstract Chlorella zofingiensis has great potential for astaxanthin and fatty acid production. This study investigated the accumulation of astaxanthin and total fatty acids (TFA), the fatty acid compositions of astaxanthin esters and TFA in photoautotrophic and heterotrophic C. zofingiensis, respectively. The results displayed that in photoautotrophic cells, 18:3 was the most predominant fatty acid, followed by 16:0, 18:2, and 18:1, while astaxanthin mono‐esters (mono‐AE) contained only 16:0 and 18:0, and astaxanthin di‐esters (di‐AE) contained 16:0 mostly, followed by 18:1, 18:0, 18:2, and 18:3. C. zofingiensis accumulated the highest level of astaxanthin and TFA under heterotrophic conditions fed with 30 g L−1 glucose. The percentage of 18:1 in TFA, mono‐AE, and di‐AE increased from 10.05%, 0%, and 17.76% to 35.80%, 14.84%, and 50.12%, respectively; in contrast, the percentages of 18:3 in TFA and di‐AE were observed to decrease from 40.42% and 7.59% to 9.56% and 1.30%, respectively, in comparison with those in photoautotrophic ones. The RNA sequencing (RNA‐seq) results showed that the expressions of the genes in astaxanthin and fatty acid biosynthetic pathways were increased under this heterotrophic condition. These results indicated differential accumulation of AE and TFA, especially fatty acid compositions of TFA and AE in photoautotrophic and heterotrophic cells, suggesting a positive correlation between astaxanthin and fatty acid biosynthesis.

Influence of agriculture fertilizer for the enhanced growth and astaxanthin production from Haematococcus lacustris RRGK isolated from Himachal Pradesh, India

In the present study, Haematococcus lacustris RRGK which is the former name of H. lacustris HPI-001 isolated from Himachal Pradesh, India, and another strain H. lacustris SAG-19a retrieved from Gottingen Culture Collection, Germany, were used. The H. lacustris SAG-19a served as a control. The both strains were grown in a Bold basal medium in which the components of NaNO3, K2HPO4∙3H2O and KH2PO4 were replaced with agriculture fertilizers such as NPK (17:17:17), urea (CH4N2O) and DAP (diammonium phosphate; (NH4)2HPO4 + potash (K2CO3) in different concentrations. The isolate of H. lacustris HPI-001 showed maximum growth at 1.2 mM NPK, while the H. lacustris SAG-19a showed maximum growth at 1.5 mM. However, both the strains showed maximum astaxanthin content at 0.6 mM NPK. The H. lacustris HPI-001 showed a maximum growth and astaxanthin content with 3.3 mM and 4.9 mM of urea, respectively, while H. lacustris SAG-19a showed maximum growth and astaxanthin accumulation with 3.3 mM and 6.6 mM of urea, respectively. The H. lacustris HPI-001 showed maximum growth at 250 mg/L (NH4)2HPO4 + 200 mg/L K2CO3 and maximum astaxanthin content at 150 mg/L (NH4)2HPO4 + 100 mg/L K2CO3, while the maximum growth in H. lacustris SAG-19a was observed at 200 mg/L (NH4)2HPO4 + 150 mg/L K2CO3, and the maximum astaxanthin content at 150 mg/L (NH4)2HPO4 + 100 mg/L K2CO3. The basal medium was also amended with the addition of commercial NaHCO3 wherein the maximum growth and content of astaxanthin in H. lacustris HPI-001 was at 0.6 mM and 1.5 mM of NaHCO3, respectively. The H. lacustris SAG-19a showed maximum growth and astaxanthin content at 1.5 mM and 0.6 mM, respectively. Based on the investigation, a medium was formulated and named as modified HPI-001 medium. The results of the present study suggest that commercial agricultural fertilizers may be used as excellent substitutes to enhance cell growth and astaxanthin production in H. lacustris.

Microalgal-Based Carbon Sequestration by Converting LNG-Fired Waste CO2 into Red Gold Astaxanthin: The Potential Applicability

The combinatorial approach of anthropogenic activities and CO2 sequestration is becoming a global research trend to alleviate the average global temperature. Although microalgae have been widely used to capture CO2 from industrial flue gas, the application of bioproducts was limited to bioenergy due to the controversy over the quality and safety of the products in the food and feed industry. Herein, the waste CO2 emitted from large point sources was directly captured using astaxanthin-hyperproducing microalgae Haematococcus pluvialis. Astaxanthin production was successfully carried out using the hypochlorous acid water-based axenic culture process under highly contamination-prone outdoor conditions. Consequently, after 36 days of autotrophic induction, the productivity of biomass and astaxanthin of H. pluvialis (the mutant) reached 0.127 g L−1 day−1 and 5.47 mg L−1 day−1 under high summer temperatures, respectively, which was 38% and 48% higher than that of wild type cell. After grinding the wet astaxanthin-enriched biomass, the extract was successfully approved by compliance validation testing from Korea Food and Drug Administration. The assorted feed improved an immune system of the poultry without causing any side effects. The flue gas-based bioproducts could certainly be used for health functional food for animals in the future.

Isolation of a Stable Astaxanthin-Hyperproducing Mutant of Xanthophyllomyces dendrorhous Through Random Mutagenesis

Astaxanthin is a red xanthophyll pigment which is widely commercially used due to its strong antioxidant properties. The heterobasidiomycetous yeast, Xanthophyllomyces dendrorhous, is one of the main microorganisms for industrial production of astaxanthin. However, astaxanthin content is low in wild type yeast strain. In our study, we had successfully isolated X. dendrorhous mutant with higher astaxanthin production capacity using chemical mutagen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), through β-ionone screening. The astaxanthin-hyperproducing mutant X. dendrorhous M34 had total carotenoid yield of 602.4 µg/g DW and a 110.8% increment of total carotenoid content compared to wild type. Survival studies indicated that MNNG treatment of yeast led to higher lethality in recipient cells compared to ethyl methanesulfonate (EMS) one. EMS-mutated strains did not show promising carotenoid yield during the screening process by β-ionone and the rate of reverse mutation was very high. In the stability test, no reversion was observed in X. dendrorhous M34 mutant after 10 successive transfers in culture broth. Reversed-phase HPLC showed that the elution profiles of carotenoid extracts of M34 and wild type X. dendrorhous were in agreement with the authentic standard and the major peak in M34 extract was identified as astaxanthin. The stable mutant with high yield of astaxanthin obtained in this work could be a suitable candidate for the industrial-scale production of astaxanthin.

Light Elicits Astaxanthin Biosynthesis and Accumulation in the Fermented Ultrahigh-Density Chlorella zofinginesis.

The growth and astaxanthin production of Chlorella zofingiensis were examined under both heterotrophic and photoautotrophic conditions, and it was found that, in comparison to the photoautotrophic mode, the heterotrophic mode led to high algal densities but attenuated intracellular astaxanthin accumulation. Following the heterotrophy-photoautotrophy transition, a considerable increase in the astaxanthin content was observed, accompanied by the upregulation of key carotenogenic genes, including phytoene synthase (PSY), β-carotenoid hydroxylase (CHYb), β-carotenoid ketolase 1 (BKT1), and β-carotenoid ketolase 2 (BKT2). In contrast, the astaxanthin content and carotenogenic genes underwent an opposite change following the photoautotrophy-heterotrophy transition, suggesting the key role of light in stimulating astaxanthin biosynthesis. To improve the astaxanthin production by C. zofingiensis, a novel heterotrophy-photoinduction culture strategy without dilution was developed and evaluated. The astaxanthin content and productivity reached 2.7 mg g-1 of dry weight and 9.9 mg L-1 day-1, respectively, which were 4.0- and 2.5-fold higher than that obtained under the heterotrophic condition.

Conditions for the Production of Carotenoids by Thraustochytrium sp. ATCC 26185 and Aurantiochytrium sp. ATCC PRA-276

ABSTRACTThere is an intensive search for alternative sources of bioactive molecules, including carotenoids, due to their potent antioxidant activities. Some aquatic microorganisms, such as thraustochytrids, have the ability to synthesize large amounts of carotenoids. The objective of this investigation was to study the effect of growth conditions (carbon: total nitrogen ratio and cultivation system) on the production of carotenoids by Thraustochytrium sp. and Aurantiochytrium sp. For Thraustochytrium sp. culture, carotenoid production was lowered by increasing the initial glucose concentration or continuous supply of glucose and nitrogen. For Aurantiochytrium sp. culture, restraining nitrogen supply or especially using a continuous supply of glucose and total nitrogen decreased total carotenoid productivity. The highest total carotenoid production (2.22 mg/L, w/v) was obtained after 192 h of cultivation of Thraustochytrium sp. using initial concentrations of 30 g/L glucose and 2.4 g/L total nitrogen (batch system). The highest production of astaxanthin was achieved in the fed-batch system with a C/N ratio of 6.2 for Thraustochytrium sp. and 40 for Aurantiochytrium sp. Therefore, it was found that the carotenoid profile can be changed by modifying the growth conditions, which can be useful for the food industry and biotechnological applications.

Manipulation of trophic capacities in Haematococcus pluvialis enables low-light mediated growth on glucose and astaxanthin formation in the dark

Haematococcus pluvialis is an industrial green microalga, which presents the best photosynthetic source of the keto-carotenoid astaxanthin due to its high content, reaching over 4% of dry weight. Astaxanthin production by Haematococcus is currently achieved by a two-stage photoautotrophic process, which involves the transition of green biomass to nitrogen starvation under high light to induce astaxanthin accumulation. This production mode is associated with high costs, due to relatively low biomass productivities and other factors. The heterotrophic mode of cultivation, based on organic carbon assimilation under controlled conditions, may offer a solution to the disadvantages of phototrophic cultivation. We created transgenic strains of H. pluvialis by transformation of the hexose uptake protein (HUP1) gene from the green microalga Parachlorella kessleri into the nuclear genome. This manipulation resulted in the ability of modified H. pluvialis strains to proliferate in the dark and under very low illumination on nutrient media supplemented with glucose. Furthermore, modified strains were able to grow and produce astaxanthin under specific conditions. All tested transformants were susceptible to the toxic glucose analogue 2‑deoxyglucose, supporting that the foreign glucose carrier was functional. Here, we report the initial characterization of the transformants cultivated on solid and in liquid media, and address the implications of manipulating trophic regimes in H. pluvialis for biotechnological applications.

Improved astaxanthin production by Xanthophyllomyces dendrorhous SK984 with oak leaf extract and inorganic phosphate supplementation.

Astaxanthin is widely used in food, feed and nutraceutical industries. Xanthophyllomyces dendrorhous is one of the most promising natural sources of astaxanthin. However, the astaxanthin yield in the wild-type X. dendrorhous is considered low for industrial application. In the present study, X. dendrorhous ATCC 66272 was subjected to two-staged mutagenesis: (i) UV light and (ii) N-methyl-N'-nitro-N-nitroso-guanidine (NTG) toward attaining higher astaxanthin yield. The UV-irradiation mutant, X. dendrorhous SK974 showed 1.7-fold (1.07mg/g) higher astaxanthin production as compared with the wild-type strain (0.65mg/g). The UV mutant strain was then treated with NTG, designated as X. dendrorhous SK984, displayed further 1.4-fold (1.45mg/g) higher astaxanthin production. Furthermore, the oak leaf extract (5%, v/v) and inorganic phosphate (KH2PO4, 3mM) supplementation resulted about 1.4-fold (1.98mg/g) higher astaxanthin production ascompared with control (1.45mg/g) in X. dendrorhous SK984. These findings serve as a platform suggesting that intersecting approaches might be aimed toward systematically enhanced astaxanthin production.

The effect of nutrients on the growth of microalgae Haematococcus lacustris (Girod-chantrans) Rostafinski 1875

Haematococcus lacustris is capable to synthesize high content of astaxanthin. Moreover, astaxanthin extracted from H.lacustris has been shown to have the highest anti-oxidativeactivity. While the demand for astaxanthin in the world is increasing, the production of astaxanthin from H. lacustris is still not easy since they have low growth rate and are very sensitive to changes in culture conditions. This study aimed at investigating the effect of nutritional factors on the growth rate of H. lacustris in order to determine the optimal medium for the biomass growth and astaxanthin synthesis of this specy. The results showed that H.lacustris grew better in RM culture medium (2.62 ± 0.17 × 105 cells/ml) than in BBM culture medium (2.44 ± 0.10 × 105 cells/ml). The highest cell density of H. lacustris was achieved in the RM medium with NaNO3 at 1200 mg/l (3.72 ± 0.022 × 105 cells/ml), and in the RM medium with K2HPO4 at 320 mg/l (3.42 ± 0.05 × 105 cells/ml).

Stimulation and Isolation of Paraphysoderma sedebokerense (Blastocladiomycota) Propagules and Their Infection Capacity Toward Their Host Under Different Physiological and Environmental Conditions.

Paraphysoderma sedebokerense (P. sedebokerense) (Blastocladiomycota) is a facultative pathogenic chytrid that causes irreversible damage to some green microalgae. Specific attacks leading to culture collapse under different conditions have only been described in the lucrative microalga Haematococcus pluvialis (H. pluvialis), while generating biomass for ketocarotenoid astaxanthin production, both indoors and outdoors. In order to manage the infection, parasite propagules (zoospores/amoeboid swarmers), the initiators of the disease, must be studied. Until now, no report on isolated P. sedebokerense propagules has been published. Here, we report on a reproducible method for the stimulation of P. sedebokerense propagule release and their isolation from fungal cultures in synthetic media and infected H. pluvialis cultures, and we further studied their development under different conditions. The isolated propagules featured different spore morphotypes, with coatless spherical spores and amoeboid swarmers being the most dominant in the first pulse of propagule release in both cultures. Inoculating the pure propagules with the host, in both the presence and absence of nitrogen, resulted in epidemic development in both green and red cells; however, in red cells, the epidemic developed more quickly in the presence of nitrogen. Biologically non-active autoclaved host cells were used to distinguish the initial stages of recognition from more progressive stages of the epidemics; on these cells, propagules encysted but did not develop further. These results prove the existence of heat-stable recognition sites on the host and an obligatory signal transduction from the host to support fungal cyst development. The propagule isolation method described herein is a breakthrough that will enable researchers to study the influence of different substances on the propagules, specifically as the initiators of the infection, and thus assist in the management of chytrid diseases. Moreover, it will be useful in studying host-parasite recognition and, therefore, will increase our understanding of the multiple chytrid infections found in nature.

Investigation on the effects of cultivation conditions, fed-batch operation, and enzymatic hydrolysate of corn stover on the astaxanthin production by Thraustochytrium striatum

Marine protists have recently been studied for the production of high-value bioactive compounds such as polyunsaturated fatty acids and carotenoids. This paper researched astaxanthin production by Thraustochytrium striatum. The studies on carbon and nitrogen sources showed that glucose and yeast extract + peptone (YEP) were the best C and N sources, respectively to achieve maximum cell growth and astaxanthin concentration/content except that ammonia chloride led to the maximum astaxanthin content. The effects of cultivation conditions were comprehensively studied on cell growth and astaxanthin production including glucose/YEP concentrations, salinity, initial medium pH, and temperature. The optimum cultivation conditions favoring cell growth were 40 g/L of glucose, 16 g/L of YEP, 100% artificial seawater of salinity, initial pH 7.0, and 15 °C. The favorable growth conditions were almost consistent with that for astaxanthin concentration, but not for astaxanthin content of cells. Glucose concentration of 40 g/L achieved the highest astaxanthin concentration of 1.5 mg/L, but the maximum astaxanthin content of 0.5 mg/g dry cell mass occurred at 100 g/L of glucose. In addition, 4.0 g/L instead of 16 g/L of YEP led to the maximum astaxanthin concentration and content. Certain oxidative stress including aeration, H2O2 and illumination were found to effectively induce astaxanthin production, but need to be well controlled at certain level. In general, unfavorable growth conditions caused growth stress that stimulated astaxanthin accumulation in cells. Using pure glucose and enzymatic hydrolysate of NaOH pretreated corn stover as a carbon source separately, we found that fed-batch was more effective than batch to achieve both high cell mass and astaxanthin production. With glucose, about double cell mass and triple astaxanthin content were achieved by fed-batch, reaching 9.7 g/L and 6.2 mg/L, respectively. The enzymatic hydrolysate could be low cost carbon source for astaxanthin production by T. striatum.

Multiple promoters driving the expression of astaxanthin biosynthesis genes can enhance free-form astaxanthin production

Astaxanthin possesses various biological properties and is used in the animal and fish feed, food, and beverage industries. In this study, we derived zeaxanthin biosynthesis genes (crtE, crtB, crtI, crtY, and crtZ) from Erwinia uredovora and crtW from Agrobacterium aurantiacum. We fused inducible and constitutive promoters to astaxanthin biosynthesis genes to construct a novel plasmid (dubbed PTP3-6) that can effectively enhance free-form astaxanthin (FFAX) production. The PTP3-6 plasmid contains one T7 promoter, driving IPTG inducible crtW expression, and three constitutive promoters (isolated from E. uredovora) driving expression of the other zeaxanthin biosynthesis genes. Escherichia coli BL21 (DE3) cells carrying the PTP3-6 plasmid produced 8.3 mg/g dry cell weight astaxanthin, which is 69.4-fold higher than has been previously reported. Using multiple promoter fusions of astaxanthin biosynthesis genes could be applied in other hosts to enhance astaxanthin production. FFAX was identified in recombinant E. coli cells through ultra-performance liquid chromatography-mass spectrometry.

Effect of linoleic acid and methyl jasmonate on astaxanthin content of Scenedesmus acutus and Chlorella sorokiniana under heterotrophic cultivation and salt shock conditions

Aquatic organisms, especially microalgae, are sources of highly bioactive metabolites which could be used in pharmaceutical, biofuels, food, agricultural, and cosmetics industries. In this research, the effect of linoleic acid (LA), as allelochemical and the precursor of two phytohormones, on astaxanthin production in Scenedesmus acutus and Chlorella sorokiniana was investigated under heterotrophic and salt stress conditions. In the absence of salt addition, addition of 32 μM LA after 96 h post inoculation during C. sorokiniana cultivation enhanced cell astaxanthin concentration 1.6 times compared to the control (no addition of LA), while the addition of 160 μM LA during the logarithmic phase of S. acutus enhanced astaxanthin production 10 times compared to the control. In C. sorokiniana under salt stress conditions, the incremental effect of LA on astaxanthin production is expanded, while salt addition did not have significant impact on astaxanthin production during S. acutus culture. In the presence of 20% salt, methyl jasmonate (MJ) treatment produced approximately threefold astaxanthin compared to LA in C. sorokiniana, while the astaxanthin formation for LA and MJ treatment in the presence of 20% salt were roughly equal during S. acutus culture. It can be therefore concluded that LA, as allelochemical and precursor of jasmonic and traumatic acid in oxylipin pathway, has an important role in the astaxanthin production in microalgae. Moreover, for the first time, the potential of LA as an enhancer of algal astaxanthin production was shown.

A novel strategy for the hyper-production of astaxanthin from the newly isolated microalga Haematococcus pluvialis JNU35

The two-stage cultivation system is widely employed for natural astaxanthin production using Haematococcus pluvialis, but the high biomass concentration of green vegetative cells (GVCs) is often difficult to achieve and little has been known about the combined photoinduction effect of light path (LP, inner diameter of 3 cm or 6 cm) and illumination mode (IM, unilateral or bilateral high light illumination). On the basis of isolating an excellent astaxanthin-producing algal strain (named H. pluvialis JNU35) and the optimized nutrient conditions, this study innovatively investigated the combined effect of LP and IM on biomass and astaxanthin hyper-production by this isolate. As a result, H. pluvialis JNU35 exhibited an ultrahigh biomass concentration of 20.1 ± 0.2 g/L and astaxanthin productivity of 18.1 mg/L/d under an optimum photoinduction combination (6 cm LP in the green stage, 3 cm LP in the red stage with bilateral high light illumination) in column photobioreactors. Moreover, an appropriate phase of GVCs being transferred into the red inductive stage was also determined to further increase the biomass concentration to 27.3 ± 0.6 g/L. By combining above optimal culture conditions, a novel culture strategy for enhancing astaxanthin production was proposed and validated in a flat-plate photobioreactor, which achieved a significant amount of astaxatnthin (5.6%, wt%) and a higher biomass concentration (3.0 g/L). This novel strategy will provide a technical solution for high-titer astaxanthin production from H. pluvialis for industrial scale.

A novel approach to enhance astaxanthin production in Haematococcus lacustris using a microstructure-based culture platform

The green alga Haematococcus lacustris is a freshwater unicellular microalga belonging to Chlorophyceae. It is a natural source of astaxanthin, a secondary metabolite commonly used as an antioxidant and anti-inflammatory agent. Due to the expansive applications of astaxanthin, efforts to increase production are underway. In this study, a novel microfabricated culture platform was developed to physically enhance intracellular stress levels of H. lacustris. The microfabricated culture device increased the level of reactive oxygen species (ROS) in the cells through physical stress, thereby inducing the production of astaxanthin. Consequently, employing the device to stress H. lacustris cells increased astaxanthin production (per cell) by up to 204%. Our novel findings in this study suggest that the microfabricated culture platform can endow mechanical stress on H. lacustris, and could serve as an attractive alternate strategy for increased astaxanthin production.

Strategy and regulatory mechanisms of glutamate feeding to enhance astaxanthin yield in Xanthophyllomyces dendrorhous

Xanthophyllomyces dendrorhous is an excellent industrial source for production of natural astaxanthin, but the yield of astaxanthin is relative low due to the contradiction between biomass weight and astaxanthin accumulation. Glutamate, a metabolite connecting nitrogen and carbon metabolisms, is probably a promising entry point to interfere cellular metabolisms. Thus, the effect of glutamate on cell growth and astaxanthin accumulation in X. dendrorhous was investigated. Results showed that glutamate feeding facilitated glucose consumption and further led to the increment of astaxanthin content with little influence of cell growth. A comparative proteomics study was applied to decipher the regulatory mechanisms of enhanced astaxanthin biosynthesis in X. dendrorhous as a response to the glutamate feeding. The expressions of proteins with the highest degree of fold change were involved in carbohydrate, amino acids, and carotenogenesis metabolisms as well as redox and stress-associated metabolisms. In addition, a possible regulatory model of enhanced astaxanthin accumulation in response to glutamate feeding in X. dendrorhous is also proposed.

Glucose triggers cell structure changes and regulates astaxanthin biosynthesis in Chromochloris zofingiensis

Heterotrophic cultivation of Chromochloris zofingiensis is considered as a promising means of astaxanthin production; however, the astaxanthin content in heterotrophic cells is generally lower than that in photoautotrophic cells. To address this issue, the regulatory effects of glucose on astaxanthin accumulation were investigated. We found that glucose could increase astaxanthin accumulation by elevating the gene expression of PSY, LCYb, CHYb and BKT within 24 h; however, after 24 h, expression of those genes in the control group was higher than that in the glucose group, leading to an increased astaxanthin content in the control group after 48 h. At 96 and 192 h, the astaxanthin contents in the control group were 1.26 and 1.27 times of those in the glucose group, respectively. Further investigation showed that, glucose treatment triggered a decrease in chlorophylls content, caused degradation of chloroplasts at 24 h, which may be the reason for the above variation in gene expression and that in astaxanthin accumulation. Moreover, glucose also caused a slight increase in total fatty acid content and altered cellular lipid composition. Collectively, these findings suggested that glucose may regulate astaxanthin accumulation through its influence on cell structure.

ИЗУЧЕНИЕ ХИМИЧЕСКОГО СОСТАВА И СВОЙСТВ БИОМАССЫ ИЗ МИКРОВОДОРОСЛЕЙ CHLORELLA SOROKINIANA ПРИ РАЗЛИЧНЫХ ВИДАХ ФИЗИЧЕСКИХ ВОЗДЕЙСТВИЙ

The paper presents data on the current issue of the processing of microalgae Chlorella sorokiniana, the richness of the vitamin and amino acid composition of which ensures its nutritional (twice as much as soy protein) and biological value. This article also provides information on the utilization of chlorella as an enrichment supplement to develop a modern Life Support System for manned spacecraft. Based on the data collected from various bibliographical studies, it is recommended to take into account the established positive effect of light exposure on the microalgae for the production of astaxanthin, as well as, to vary the composition of the nutrient medium in order to obtain a dry microalgae biomass with a fixed lipid, protein and starch content. The influence of various physical factors on the specificity of biochemical processes in the cell and the variation in the composition of dry biomass in the cultivation of Chlorella sorokiniana was studied. Experimental results of the application of a red laser (output power 1.6 mW, wavelength 0.63 µm), the exposure to daylight (intensity 2800 Lux), infrared (power 250 W, intensity 14100 Lux) and ultraviolet (wavelength 280-315 nm) radiations of the microalgal samples are presented. The most significant concentrations of protein compounds (46.0% and 48.4% of dry biomass) were obtained after the exposure to daylight and to infrared radiation. In the last case, the fatty acid composition of the sample was represented mainly by unsaturated acids (77% by weight). The biomass of C. sorokiniana cultivated under the influence of daylight showed an increased content of chlorophylls a (19.3 mg/g), chlorophyll b (7.1 mg/g) and of total carotenoids (2.8 mg/g). Under the action of ultraviolet light, the quantity of saccharides increased (up to 430 mg/g). The data obtained enables to select optimal cultivation conditions of Chlorella sorokiniana in order to obtain a biomass with a given composition and properties.

Accumulation of Astaxanthin Was Improved by the Nonmotile Cells of Haematococcus pluvialis

The current commercial production of natural astaxanthin is mainly carried out using Haematococcus pluvialis vegetative cells in the “two-stage” batch mode. The motile vegetative cells are more sensitive to stress than nonmotile vegetative cells, thereby affecting the overall astaxanthin productivity in H. pluvialis cultures. In this study, we compared the differences between motile cells and nonmotile cells in astaxanthin productivity, morphological changes, the mortality rate, and the diameter of the formed cysts. The experimental design was achieved by two different types H. pluvialis cell under continuous light of 80 μmol photons m−2 s−1 for a 9-day induction period. The highest astaxanthin concentration of 48.42 ± 3.13 mg L−1 was obtained in the nonmotile cell cultures with the highest the productivity of 5.04 ± 0.15 mg L−1 day−1, which was significantly higher than that in the motile cell cultures. The microscopic examination of cell morphological showed a large number of photooxidative damaged cells occurring in the motile cell cultures, resulting in higher cell mortality rate (22.2 ± 3.97%) than nonmotile cell cultures (9.6 ± 0.63%). In addition, the analysis results of cell diameter statistics indicated that nonmotile cells were more conducive to the formation of large astaxanthin-rich cysts than motile cells. In conclusion, the works presented here suggest that the accumulation of astaxanthin was significantly improved by nonmotile cells of H. pluvialis, which provided a possibility of optimizing the existing H. pluvialis cultivation strategy for the industrial production.

The road to astaxanthin production in tomato fruit reveals plastid and metabolic adaptation resulting in an unintended high lycopene genotype with delayed over-ripening properties.

SummaryTomato fruit are an important nutritional component of the human diet and offer potential to act as a cell factory for speciality chemicals, which are often produced by chemical synthesis. In the present study our goal was to produce competitive levels of the high value ketocarotenoid, astaxanthin, in tomato fruit. The initial stage in this process was achieved by expressing the 4, 4′ carotenoid oxygenase (crtW) and 3, 3′ hydroxylase (crtZ) from marine bacteria in tomato under constitutive control. Characterization of this genotype showed a surprising low level production of ketocarotenoids in ripe fruit but over production of lycopene (~3.5 mg/g DW), accompanied by delayed ripening. In order to accumulate these non‐endogenous carotenoids, metabolite induced plastid differentiation was evident as well as esterification. Metabolomic and pathway based transcription studies corroborated the delayed onset of ripening. The data also revealed the importance of determining pheno/chemotype inheritance, with ketocarotenoid producing progeny displaying loss of vigour in the homozygous state but stability and robustness in the hemizygous state. To iteratively build on these data and optimize ketocarotenoid production in this genotype, a lycopene β‐cyclase was incorporated to avoid precursor limitations and a more efficient hydroxylase was introduced. These combinations resulted in the production of astaxanthin (and ketocarotenoid esters) in ripe fruit at ~3 mg/g DW. Based on previous studies, this level of product formation represents an economic competitive value in a Generally Regarded As Safe (GRAS) matrix that requires minimal downstream processing.