Intraperitoneal and dietary administration of astaxanthin in rainbow trout (Oncorhynchus mykiss)--plasma uptake and tissue distribution of geometrical E/Z isomers

Astaxanthin enters circulation in salmonid fishes upon intraperitoneal injection (IP) of small doses. Blood uptake and tissue distribution of geometrical E/Z astaxanthin isomers were determined in tissues and plasma of duplicated groups of rainbow trout (Oncorhynchus mykiss, initial weight 550 g) some of which were administered high doses of astaxanthin by IP in a trial lasting for 8 weeks. Doses of 10 (IP10), 50 (IP50) or 100 mg (IP100) astaxanthin (Lucantin Pink, BASF, Germany), respectively, dispersed in phosphate buffered saline were tested in comparison with diets containing 10 (Control) or 60 (Fed 60) mg astaxanthin kg(-1). Astaxanthin concentrations in all examined tissues and plasma were significantly higher in IP50 and IP100 than in controls and Fed 60 (p<0.05). In IP50, 11 mg astaxanthin kg(-1) muscle was detected after 4 weeks, compared to 4 mg kg(-1) in rainbow trout fed 60 mg kg(-1). Concentrations up to 80 and 100 mg astaxanthin kg(-1) were detected in liver and kidney after IP, respectively, whereas fish only fed astaxanthin contained about 2 mg astaxanthin kg(-1). No increase in muscle astaxanthin concentration was found between 4 and 8 weeks in fish given IP, and the muscle astaxanthin concentration in IP50 and IP100 were similar. Muscle concentration and injected dose were curvilinearly correlated and the proportion of ingested dose retained by the muscle was negatively correlated with the amount of injected astaxanthin. Plasma and muscle concentrations of astaxanthin were highly correlated (p<0.0001). Astaxanthin Z-isomers accumulated selectively in the various tissues after IP, whereas all-E-astaxanthin was preferably absorbed into plasma when administered via the diet. There was a selective uptake of all-E-astaxanthin in the muscle of all fish. Mortality was not affected by treatment, but a dose-dependent reduction in SGR was evident after IP. In conclusion, a more rapid and higher uptake of astaxanthin in plasma, muscle, kidney and liver of rainbow trout takes place after IP compared to when astaxanthin is fed via the diet.     

Engineered maize as a source of astaxanthin: processing and application as fish feed

Astaxanthin from a transgenic maize line was evaluated as feed supplement source conferring effective pigmentation of rainbow trout flesh. An extraction procedure using ethanol together with the addition of vegetal oil was established. This resulted in an oily astaxanthin preparation which was not sufficiently concentrated for direct application to the feed. Therefore, a concentration process involving multiple phase partitioning steps was implemented to remove 90 % of the oil. The resulting astaxanthin raw material contained non-esterified astaxanthin with 12 % 4-keto zeaxanthin and 2 % zeaxanthin as additional carotenoids. Isomeric analysis confirmed the exclusive presence of the 3S, 3′S astaxanthin enantiomer. The geometrical isomers were 89 % all-E, 8 % 13-Z and 3 % 9-Z. The incorporation of the oily astaxanthin preparation into trout feed was performed to deliver 7 mg/kg astaxanthin in the final feed formulation for the first 3.5 weeks and 72 mg/kg for the final 3.5 weeks of the feeding trial. The resulting pigmentation of the trout fillets was determined by hue values with a colour meter and further confirmed by astaxanthin quantification. Pigmentation properties of the maize-produced natural astaxanthin incorporated to 3.5 µg/g dw in the trout fillet resembles that of chemically synthesized astaxanthin. By comparing the relative carotenoid compositions in feed, flesh and feces, a preferential uptake of zeaxanthin and 4-keto zeaxanthin over astaxanthin was observed.     

Effects of astaxanthin in obese mice fed a high-fat diet

Astaxanthin is a natural antioxidant carotenoid that occurs in a wide variety of living organisms. We investigated the effects of astaxanthin supplementation in obese mice fed a high-fat diet. Astaxanthin inhibited the increases in body weight and weight of adipose tissue that result from feeding a high-fat diet. In addition, astaxanthin reduced liver weight, liver triglyceride, plasma triglyceride, and total cholesterol. These results suggest that astaxanthin might be of value in reducing the likelihood of obesity and metabolic syndrome in affluent societies.     

Bioavailability of Astaxanthin in Haematococcus Algal Extract: The Effects of Timing of Diet and Smoking Habits

Astaxanthin is a caroteonid that possesses strong antioxidant activity. Recently, many studies on biological activity have been reported. In general, the absorption of carotenoids is affected greatly by diet and by smoking. In this report, we investigated astaxanthin pharmacokinetics after administration of Haematococcus algal extract, a source of astaxanthin, to smokers and nonsmokers before and after a meal; astaxanthin was given before the meal to nonsmokers (n=7), after the meal to nonsmokers (n=6), and after the meal to smokers (n=7), then serum samples were analyzed. The timing of administration greatly affected astaxanthin bioavailability including the area under the curve (AUC_0–168, 2,968±959 μg h/l in the before-meal group vs. 7,219±3,118 μg h/l in the after-meal group), indicating high availability in the after-meal group. Smoking also affected the pharmacokinetic parameters and reduced the half-life (t_1?2) of astaxanthin elimination significantly.     

Application of resonance raman microscopy to in vivo carotenoid

The high antioxidant activity of astaxanthin has been attracted considerable attention in these days. One of the major antioxidant activities of this carotenoid is anti-photoaging. We have been focusing our attention on this particular issue. The anti-photoaging activity should be functioning in inner skin. In this study we tried to find out the fact that astaxanthin that has been swabbed on the outer surface of the skin has really passed through and reached to the inner skin. For this purpose resonance Raman microscopy was applied to the rat skin sample on which astaxanthin was swabbed on its outer surface. Astaxanthin gives rise to a unique Raman spectrum that is characteristic of its molecular structure. Therefore, we can easily identify the presence or absence of astaxanthin in the area of the rat skin that is subjected to this spectroscopic measurement. We used 532 nm laser light for probing the resonance Raman scattering of astaxanthin. Astaxanthin shows three strong Raman lines at 1508, 1145, and 993 cm(-1). These three lines are ascribable to the C=C stretching, C-C stretching, and C-CH(3) in-plane rocking vibrational modes, respectively. We have constructed confocal Raman microscope that has the spatial resolution of ca. 500 nm. Three-dimensional mapping of the Raman spectrum of astaxanthin has been performed in order to determine its distribution in the rat skin.     

Plasma appearance of unesterified astaxanthin geometrical E/Z and optical R/S isomers in men given single doses of a mixture of optical 3 and 3'R/S isomers of astaxanthin fatty acyl diesters

Appearance, pharmacokinetics and distribution of astaxanthin all-E-, 9Z- and 13Z-geometrical and (3R,3'R)-, (3R,3'S)- and (3S,3'S)-optical isomers in plasma fractions were studied in three middle-aged male volunteers (41-50 years) after ingestion of a single meal containing first a 10-mg dose equivalent of astaxanthin from astaxanthin diesters, followed by a dose of 100 mg astaxanthin equivalents after 4 weeks. Direct resolution of geometrical isomers and optical isomers of astaxanthin dicamphanates by HPLC after saponification showed that the astaxanthin consisted of 95.2% all-E-, 1.2% 9Z- and 3.6% 13Z-astaxanthin, of (3R,3'R)-, (3R,3'S; meso)- and (3S,3'S)-astaxanthin in a 31:49:20 ratio. The plasma astaxanthin concentration-time curves were measured during 76 h. Astaxanthin esters were not detected in plasma. Maximum levels of astaxanthin (C(max)=0.28+/-0.1 mg/l) were reached 11.5 h after administration and the plasma astaxanthin elimination half-life was 52+/-40 h. The C(max) at the low dose was 0.08 mg/l and showed that, the dose response was non-linear. The (3R,3'R)-astaxanthin optical isomer accumulated selectively in plasma compared to the (3R,3'S)- and (3S,3'S)-isomers, and comprised 54% of total astaxanthin in the blood and only 31% of total astaxanthin in the administered dose. The astaxanthin Z-isomers were absorbed selectively into plasma and comprised approximately 32% of total astaxanthin 6-7.5 h postprandially. The proportion of all-E-astaxanthin was significantly higher in the very low density lipoproteins and chylomicrons (VLDL/CM) plasma lipoprotein fraction than in the high density lipoproteins (HDL) and low denisty lipoproteins (LDL) fractions (P<0.05). The results indicate that a selective process increase the relative proportion of astaxanthin Z-isomers compared to the all-E-astaxanthin before uptake in blood and that the astaxanthin esters are hydrolyzed selectively during absorption.     

Plasma appearance and distribution of astaxanthin E/Z and R/S isomers in plasma lipoproteins of men after single dose administration of astaxanthin

Appearance, pharmacokinetics, and distribution of astaxanthin E/Z and R/S isomers in plasma and lipoprotein fractions were studied in 3 middle-aged male volunteers (37-43 years) after ingestion of a single meal containing a 100 mg dose of astaxanthin. The astaxanthin source consisted of 74% all-E-, 9% 9Z-, 17% 13Z-astaxanthin (3R,3'R-, 3R,3'S; meso-, and 3S,3'S-astaxanthin in a 1:2:1 ratio). The plasma astaxanthin concentration--time curves were measured during 72 hr. Maximum levels of astaxanthin (1.3 +/- 0.1 mg/L) were reached 6.7 +/- 1.2 hr after administration, and the plasma astaxanthin elimination half-life was 21 +/- 11 hr. 13Z-Astaxanthin accumulated selectively, whereas the 3 and 3'R/S astaxanthin distribution was similar to that of the experimental meal. Astaxanthin was present mainly in very low-density lipoproteins containing chylomicrons (VLDL/CM; 36-64% of total astaxanthin), whereas low-density lipoprotein (LDL) and high-density lipoprotein (HDL) contained 29% and 24% of total astaxanthin, respectively. The astaxanthin isomer distribution in plasma, VLDL/CM, LDL, and HDL was not affected by time. The results indicate that a selective process increases the relative proportion of astaxanthin Z-isomers compared to the all-E-astaxanthin during blood uptake and that astaxanthin E/Z isomers have similar pharmacokinetics.     

Astaxanthin improves muscle lipid metabolism in exercise via inhibitory effect of oxidative CPT I modification

Intracellular redox balance may affect nutrient metabolism in skeletal muscle. Astaxanthin, a carotenoid contained in various natural foods, exerts high antioxidative capacity in the skeletal muscles. The present study investigated the effect of astaxanthin on muscle lipid metabolism in exercise. ICR mice (8 weeks old) were divided into four different groups: sedentary, sedentary treated with astaxanthin, running exercise, and exercise treated with astaxanthin. After 4 weeks of treatment, exercise groups performed treadmill running. Astaxanthin increased fat utilization during exercise compared with mice on a normal diet with prolongation of the running time to exhaustion. Colocalization of fatty acid translocase with carnitine palmitoyltransferase I (CPT I) in skeletal muscle was increased by astaxanthin. We also found that hexanoyl-lysine modification of CPT I was increased by exercise, while astaxanthin prevented this increase. In additional experiment, we found that astaxanthin treatment accelerated the decrease of body fat accumulation with exercise training. Our results suggested that astaxanthin promoted lipid metabolism rather than glucose utilization during exercise via CPT I activation, which led to improvement of endurance and efficient reduction of adipose tissue with training.     

Iron overload prevents oxidative damage to rat brain after chlorpromazine administration

The hypothesis tested is that Fe administration leads to a response in rat brain modulating the effects of later oxidative challenges such as chlorpromazine (CPZ) administration. Either a single dose (acute Fe overload) or 6 doses every second day (sub-chronic Fe overload) of 500 or 50 mg Fe-dextran/kg, respectively, were injected intraperitoneally (ip) to rats. A single dose of 10 mg CPZ/kg was injected ip 8 h after Fe treatment. DNA integrity was evaluated by quantitative PCR, lipid radical (LR^·) generation rate by electron paramagnetic resonance (EPR), and catalase (CAT) activity by UV spectrophotometry in isolated brains. The maximum increase in total Fe brain was detected after 6 or 2 h in the acute and sub-chronic Fe overload model, respectively. Mitochondrial and nuclear DNA integrity decreased after acute Fe overload at the time of maximal Fe content; the decrease in DNA integrity was lower after sub-chronic than after acute Fe overload. CPZ administration increased LR^· generation rate in control rat brain after 1 and 2 h; however, CPZ administration after acute or sub-chronic Fe overload did not affect LR^· generation rate. CPZ treatment did not affect CAT activity after 1–4 h neither in control rats nor in acute Fe-overloaded rats. However, CPZ administration to rats treated sub-chronically with Fe showed increased brain CAT activity after 2 or 4 h, as compared to control values. Fe supplementation prevented brain damage in both acute and sub-chronic models of Fe overload by selectively activating antioxidant pathways.     

The antianxiety-like effect of astaxanthin extracted from Paracoccus carotinifaciens

Astaxanthin is a red carotenoid pigment and is widely found in living organisms. Astaxanthin has a potent antioxidative ability and has been reported as having various biological effects on the central nerve system, such as a protective effect against ischemia/reperfusion injury and improvement in cognitive function. In this study, to investigate the effects of astaxanthin on anxiety and depression, we performed some behavioral trials including the elevated plus maze test, hole-board test, forced swim test, and tail suspension test. Astaxanthin (100 and 300 mg/kg/day for 10 days, p.o.) significantly increased the time spent in open arms in the elevated plus maze test and increased the head-dipping count and duration in the hole-board test. On the other hand, astaxanthin (10, 100, 300, and 500 mg/kg/day for 10 days, p.o.) did not change the immobility time in the forced swim test or the tail suspension test. In conclusion, in mice, astaxanthin exerted anxiolytic-like effects, but not antidepressant-like effects.     

Astaxanthin from the red crab langostilla (Pleuroncodes planipes): optical R/S isomers and fatty acid moieties of astaxanthin esters

The composition of the fatty acids of astaxanthin esters and the distribution of astaxanthin optical RS isomers in the esterified and unesterified astaxanthin fractions extracted from the meal of the pelagic red crab langostilla (Pleuroncodes planipes; Decapoda, Anomura) were determined. Astaxanthin diesters comprised approximately 70%, monoesterified astaxanthin approximately 12%, and unesterified astaxanthin approximately 10% of total carotenoids, respectively. Unidentified carotenes and minor yellow xanthophylls represented approximately 8% of the total carotenoids. Three astaxanthin diester fractions (ratio 5:4:1) and one monoester fraction were clearly distinguished by thin-layer chromatography, and fatty acid moieties were determined in all of them. Saturated fatty acids accumulated in astaxanthin diesters, but were reduced in the monoester fraction when compared to langostilla crude oil extract (CE). Astaxanthin diesters, but not monoesters were enriched in C16:0 and C18:1n-9, when compared to the CE. Astaxanthin monoesters were rich in polyunsaturated fatty acids (approximately 70% of total fatty acids), in particular C20:5n-3 and C22:6n-3. Acylation of astaxanthin in langostilla seems to be selective rather than specific. The three diesterified astaxanthin fractions of langostilla had a ratio of approximately 3:1:3 between the (3R,3'R)-, (3R,3'S)-, and (3S,3'S)-astaxanthin isomers, whereas in the monoesterified and unesterified fractions the ratio was approximately 4:1:4. The astaxanthin optical RS isomer composition indicates that langostilla is unable to racemize astaxanthin.     

II - Insulin processing in mitochondria

Our objective was to know how insulin is processing in mitochondria; if IDE is the only participant in mitochondrial insulin degradation and the role of insulin degradation on IDE accumulation in mitoplasts. Mitochondria and its fractions were isolated as described by Greenwalt. IDE was purified and detected in immunoblot with specific antibodies. High insulin degradation was obtained through addition to rat’s diet of 25 g/rat of apple and 10 g/rat of hard-boiled eggs, 3 days a week. Mitochondrial insulin degradation was assayed with 5 % TCA, insulin antibody or Sephadex G50 chromatography. Degradation was also assayed 60 min at 37 °C in mitochondrial fractions (IMS and Mx) with diet or not and without IDE. Degradation in fractions precipitated with ammonium sulfates (60–80 %) were studied after mitochondrial insulin incubation (1 ng. insulin during 15 min, at 30 °C) or with addition of 2.5 mM ATP. Supplementary diet increased insulin degradation. High insulin did not increase mitoplasts accumulation and did not decrease mitochondrial degradation. High insulin and inhibition of degradation evidence insulin competition for a putative transport system. Mitochondrial incubation with insulin increased IDE in matrix as observed in immunoblot. ATP decreased degradation in Mx and increased it in IMS. Chromatography of IMS demonstrated an ATP-dependent protease that degraded insulin, similar to described by Sitte et al. Mitochondria participate in insulin degradation and the diet increased it. High insulin did not accomplish mitochondrial decrease of degradation or its accumulation in mitoplasts. Mitochondrial incubation with insulin increased IDE in matrix. ATP suggested being a regulator of mitochondrial insulin degradation.     

In Vivo Effects of Free Form Astaxanthin Powder on Anti-Oxidation and Lipid Metabolism with High-Cholesterol Diet

Astaxanthin extracted from Pomacea canaliculata eggs was made into free-form astaxanthin powder (FFAP) and its effects on lipid metabolism, liver function, antioxidants activities and astaxanthin absorption rate were investigated. 45 hamsters were split into 5 groups and fed with normal diet, high-cholesterol control (0.2% cholesterol), 1.6FFAP (control+1.6% FFAP), 3.2FFAP (control+3.2% FFAP) and 8.0FFAP (control+8.0% FFAP), respectively, for 6 weeks. FFAP diets significantly decreased the liver total cholesterol, triglyceride levels and increased liver fatty acids (C20:5n3; C22:6n3) compositions. It decreased plasma alanine aminotransferase and aspartate aminotransferase. In terms of anti-oxidative activities, we found 8.0 FFAP diet significantly decreased plasma and liver malonaldehyde (4.96±1.96 μg TEP eq./mL and 1.56±0.38 μg TEP eq./g liver) and liver 8-isoprostane levels (41.48±13.69 μg 8-ISOP/g liver). On the other hand, it significantly increased liver catalase activity (149.10±10.76 μmol/min/g liver), Vitamin C (2082.97±142.23 μg/g liver), Vitamin E (411.32±81.67 μg/g liver) contents, and glutathione levels (2.13±0.42 mg GSH eq./g liver). Furthermore, 80% of astaxanthin absorption rates in all FFAP diet groups suggest FFAP is an effective form in astaxanthin absorption. Finally, astaxanthin was found to re-distribute to the liver and eyes in a dose dependent manner. Taken together, our results suggested that the appropriate addition of FFAP into high cholesterol diets increases liver anti-oxidative activity and reduces the concentration of lipid peroxidase and therefore, it may be beneficial as a material in developing healthy food.     

The Effect of Ethionine Feeding on the Retention of A Single Per Os Dose of Methyl Mercury on Rat

Six adult female rats were daily fed a diet containing DL-ethionine during three weeks. One daily rat dose was 30 mg of ethionine. Six similar rats, the controls, were kept on the same diet without ethionine. On the 21st day of the experiment all rats were given one dose of 203Hg labeled methyl mercury by stomach tube. Each rat received 163 µg in terms of metallic mercury. Ninety hrs. after the mercury administration all rats were sacrificed and the mercury contents of the brains, livers, caudal femoral muscles, erythrocytes and blood plasma were determined. The mean plasma mercury content was significantly (P<0.01) greater in the ethionine fed rats when compared to the controls.     

An improved process for cell disruption and astaxanthin extraction from Phaffia rhodozyma

Phaffia rhodozyma is one of the most important natural sources of the carotenoid astaxanthin, and the key process for extracting intracellular astaxanthin is disrption of the thick cell wall. In this work, an improved process for cell disruption and astaxanthin extraction from Phaffica rhodozyma was studied using an autoclave at low acid concentration. Under the optimum conditions (HCl 0.5 M and autoclave pressure 0.1 Mpa, 15 min), the relative residual astaxanthin and astaxanthin extractability reached 90.4 ± 3.5% and 84.8 ± 3.2%, respectively. The scanning electron microscopy pictures showed that all yeast cells shattered into fragments after autoclave treatment at low acid concentration condition, whereas cells were intact or partly broken after treatment by some other physical and chemical processes. This new method left no residual toxin and gavehigher extraction recovery, with good prospects for industrial use.     

雨生红球藻的光周期效应

雨生红球藻(Haematococcus pluvialis)是一种单细胞淡水绿藻, 是自然界已知的中虾青素含量最高的生物物种。通过分析3种光照强度(70、120和300 μmol·m^–2·s^–1)下雨生红球藻细胞形态、生长速率和虾青素含量的差异, 对其光周期效应进行了研究。结果表明, 不同光强下适宜雨生红球藻生长的光周期均为16小时光照/8小时黑暗, 光强为120 μmol·m^–2·s^–1时其细胞生长速率最大, 为0.43 d^–1; 细胞内虾青素含量随着光强和光照时间的增加而增加, 在300 μmol·m^–2·s^–1光强下连续光照15天后, 藻细胞呈亮红色, 平均直径为21.02 μm, 最大虾青素值达39.40 pg·cell^–1。     

Retinol-deficient rats can convert a pharmacological dose of astaxanthin to retinol: antioxidant potential of astaxanthin, lutein, and β-carotene

Retinol (ROH) and provitamin-A carotenoids are recommended to treat ROH deficiency. Xanthophyll carotenoids, being potent antioxidants, can modulate health disorders. We hypothesize that nonprovitamin-A carotenoids may yield ROH and suppress lipid peroxidation under ROH deficiency. This study aimed to (i) study the possible bioconversion of astaxanthin and lutein to ROH similar to β-carotene and (ii) determine the antioxidant potential of these carotenoids with reference to Na(+)/K(+)-ATPase, antioxidant molecules, and lipid peroxidation (Lpx) induced by ROH deficiency in rats. ROH deficiency was induced in rats (n = 5 per group) by feeding a diet devoid of ROH. Retinol-deficient (RD) rats were gavaged with astaxanthin, lutein, β-carotene, or peanut oil alone (RD group) for 7 days. Results show that the RD group had lowered plasma ROH levels (0.3 μmol/L), whereas ROH rose in astaxanthin and β-carotene groups (4.9 and 5.7 μmol/L, respectively), which was supported by enhanced (69% and 70%) intestinal β-carotene 15,15'-monooxygenase activity. Astaxanthin, lutein, and β-carotene lowered Lpx by 45%, 41%, and 40% (plasma), respectively, and 59%, 64%, and 60% (liver), respectively, compared with the RD group. Lowered Na(+)/K(+)-ATPase and enhanced superoxide dismutase, catalase, and glutathione-S-transferase activities support the lowered Lpx. To conclude, this report confirms that astaxanthin is converted into β-carotene and ROH in ROH-deficient rats, and the antioxidant potential of carotenoids was in the order astaxanthin > lutein > β-carotene.     

Lycopene Inhibits Ischemia/Reperfusion-Induced Neuronal Apoptosis in Gerbil Hippocampal Tissue

Plant lycopene exhibits antioxidant activity in animal tissues. Transient cerebral ischemia/reperfusion in Mongolian gerbils resulted in delayed neuronal death in hippocampal regions. We examined the antioxidant effects of lycopene because we expected lycopene to attenuate ischemia-related neuronal damage by controlling apoptosis at the gene level. The gerbils were divided into two groups: the normal feeding (control) group that received normal market food (MF) and the lycopene group that received MF containing lycopene (5 mg in 100 g MF food). After 1.5–2.0 months (when body weight were 60–65 g), the lycopene level was 38.2 ± 17.6 ng/ml in serum and 11.9 ± 4.0 μg/g-wet weight tissue in the liver. Levels of B cell leukemia-2, an apoptosis-suppressing protein, decreased in control animal brains 1, 3, and 7 days after surgery, whereas the levels increased in lycopene-treated animal brains. Moreover, cysteinyl aspartate-specific protease-3 activity increased gradually after ischemia, but was suppressed in the lycopene-treated animal brains 7 days after surgery. Finally, hippocampal superoxide dismutase (SOD) activity decreased in the control group 3 h after ischemia and, gradually increased thereafter, whereas it was significantly elevated in the lycopene group. Thus, orally administered lycopene is accumulated in the body, and provided protections against ischemia/reperfusion-induced brain injury by inducing an increase in SOD activity and inhibiting apoptosis.     

Influence of sodium orthovanadate on the production of astaxanthin from green algae Haematococcus lacustris

Astaxanthin production is commonly induced under stress conditions such as nutrient deficiency (N or P), high light stress, and variations of temperature, high NaCl concentrations, and other factors. The objective of the present study is the analysis of the effect of oxidative stress by sodium orthovanadate (SOV), a nonspecific inhibitor of protein tyrosine phosphatases, on the cells growth and astaxanthin production of H. lacustris. In the presence of SOV (lower than 5.0 mM), maximum growth of H. lacustris obtained was 2.4 × 10⁵ cells/mL in MBBM medium at 24°C under continuous illumination (40 μE/m²/s) of white fluorescent light, with continuous aeration of CO₂ (0.2 vvm). Total carotenoids accumulated per cell biomass unit treated with 2.5 mM SOV has approximately shown 2.5 folds higher than the control after short period of SOV induction time as 2 days, despite that cells were grown under normal light. Meanwhile, maximal astaxanthin production from H. lacustris was 10.7 mg/g biomass in MBBM with 5 days of continuous illumination at 40 μE/m²/s, which has been established as optimal light intensity for the control culture of H. lacustris. Treating algae H. lacustris with sodium orthovanadate showed promoting the accumulation of astaxanthin by advancing either the inhibition of dephosphorylation or synthesis of ATP. Its potential role of PTPases in microalgae H. lacustris is discussed. The first two authors are equally contributed to this work.     

Utilization of cane molasses towards cost-saving astaxanthin production by a Chlorella zofingiensis mutant

The aim of the present study was to survey the growth and astaxanthin production of E17, an astaxanthin-rich mutant of Chlorella zofingiensis, through feeding the low-cost carbon source cane molasses. In heterotrophic batch cultivation, E17 fed with pretreated molasses achieved biomass (1.79 g L^?1 day^?1) and astaxanthin (1.99 mg L^?1 day^?1) productivities comparable to those with glucose, which were about 2- and 2.8-fold of those fed with untreated molasses, respectively. Molasses-induced astaxanthin accumulation may be attributed to the elicited expression of carotenogenic genes, in particular the genes specifically responsible for the ketolation and hydroxylation of β-carotene to form astaxanthin. A two-stage fed-batch strategy was employed to grow E17 and induce astaxathin accumulation, resulting in 45.6 g L^?1 biomass and 56.1 mg L^?1 astaxanthin, the highest volumetric astaxanthin yield ever reported for this alga. In addition, the astaxanthin production by E17 was tested with a semi-continuous culture method, where the directly diluted raw molasses (giving 5 g L^?1 sugar) was used as the carbon source. Little growth inhibition of E17 was observed in the semi-continuous culture with a biomass productivity of 1.33 g L^?1 day^?1 and an astaxanthin productivity of 0.83 mg L^?1 day^?1. The mixotrophic semi-continuous cultures enhanced the biomass and astaxanthin productivities by 29.3 % and 42.2 %, respectively. This study highlights the potential of using the industrially cheap cane molasses towards large-scale cost-saving production of the high-value ketocarotenoid astaxanthin.