β-Carotene is a terpenoid molecule with high hydrophobicity that is often used as an additive in foods and feed. Previous work has demonstrated the heterologous biosynthesis of β-carotene from an ...intrinsic high flux of acetyl-CoA in 12 steps through 11 genes in Yarrowia lipolytica. Here, an efficient biosynthetic pathway capable of producing 100-fold more β-carotene than the baseline construct was generated using strong promoters and multiple gene copies for each of the 12 steps. Using fed-batch fermentation with an optimized medium, the engineered pathway could produce 4g/L β-carotene, which was stored in lipid droplets within engineered Y. lipolytica cells. Expansion of these cells for squalene production also demonstrated that Y. lipolytica could be an industrially relevant platform for hydrophobic terpenoid production.
•The first time engineering Yarrowia lipolytica for heterologous β-carotene synthesis.•β-carotene production titer achieved in this study is the highest level so far.•Y. lipolytica has the potential to serve as an excellent host for hydrophobic terpenoids production.
Background: Golden Rice (GR) has been genetically engineered to be rich in β-carotene for use as a source of vitamin A.Objective: The objective was to compare the vitamin A value of β-carotene in GR ...and in spinach with that of pure β-carotene in oil when consumed by children.Design: Children (n = 68; age 6–8 y) were randomly assigned to consume GR or spinach (both grown in a nutrient solution containing 23 atom% 2H2O) or 2H8β-carotene in an oil capsule. The GR and spinach β-carotene were enriched with deuterium (2H) with the highest abundance molecular mass (M) at Mβ-C+2H10. 13C10Retinyl acetate in an oil capsule was administered as a reference dose. Serum samples collected from subjects were analyzed by using gas chromatography electron-capture negative chemical ionization mass spectrometry for the enrichments of labeled retinol: Mretinol+4 (from 2H8β-carotene in oil), Mretinol+5 (from GR or spinach 2H10β-carotene), and Mretinol+10 (from 13C10retinyl acetate).Results: Using the response to the dose of 13C10retinyl acetate (0.5 mg) as a reference, our results (with the use of AUC of molar enrichment at days 1, 3, 7, 14, and 21 after the labeled doses) showed that the conversions of pure β-carotene (0.5 mg), GR β-carotene (0.6 mg), and spinach β-carotene (1.4 mg) to retinol were 2.0, 2.3, and 7.5 to 1 by weight, respectively.Conclusions: The β-carotene in GR is as effective as pure β-carotene in oil and better than that in spinach at providing vitamin A to children. A bowl of ∼100 to 150 g cooked GR (50 g dry weight) can provide ∼60% of the Chinese Recommended Nutrient Intake of vitamin A for 6–8-y-old children. This trial was registered at www.clinicaltrials.gov as NCT00680212.
The aim of the study was to determine whether two postpartum intramuscular treatments with 200 mg of beta-(β-)carotene (Carofertin; Alvetra u. Werfft, Vienna, Austria) in a 14-day interval increases ...β-carotene concentrations in blood, particularly around the time of the first artificial insemination (AI), and to test the effect of the treatment on fertility parameters, luteal size, and progesterone blood levels of dairy cows. A total of 297 Holstein dairy cows were enrolled in the study. Between 28 and 34 days postpartum (dpp) β-carotene concentrations were measured in blood samples using an on-site test (iCheck carotene; BioAnalyt, Teltow, Germany). Cows with a β-carotene concentration <3.5 mg/L, indicating a deficiency of β-carotene, were allocated either to the β-carotene treatment group BCT (n = 123) or to the control group CON (n = 121). Cows with concentrations ≥3.5 mg/L were assigned to an optimally supplied reference group (REF; n = 53). Cows in the BCT group received 200 mg of β-carotene intramuscularly at 28–34 dpp and at 42–48 dpp. Further blood samples were collected at 35–41 dpp, 42–48 dpp, 49–55 dpp, and in the week after the first AI and their β-carotene concentrations were analyzed. Between day 10 and 14 after the first AI, the blood progesterone concentration was measured and the size of the corpus luteum (CL) was determined by ultrasound. Blood β-carotene concentrations increased in the BCT cows in the week after the treatment with a peak at 49–55 dpp and were significantly higher than in the CON group at each time point after the first treatment. Logistic regression models, however, revealed that the treatment with β-carotene had no effect on first service conception rate, days to first service, time to pregnancy, or percentage of pregnant cows within 150 dpp. Furthermore, there was no effect on progesterone concentration or the size of the CL between the groups. In conclusion, two treatments with Carofertin postpartum increased β-carotene blood concentrations but had no effect on the fertility parameters in this study.
•Administration of β-carotene increased blood β-carotene concentrations in dairy cows.•Two postpartum administrations of beta-carotene did not improve fertility in dairy cows.•No effect on luteal size.•No effect on blood progesterone levels.•Results should be interpreted as herd specific.
Information on the physicochemical variability in rapeseed oil from different varieties during each refining process is lacking. Our purpose was to investigate the physicochemical properties, ...micronutrients and oxidative stability of the oil extracted from the five varieties of rapeseeds during their different stages of refining process. Increase in the acid value, peroxide value and p-anisidine value were detected in the refining, while content of tocopherols, sterols, β-carotene and phenols, which are regarded as important nutritional compounds diminished. Moreover, the loss rate of total phytosterols of all oils during neutralization (9.23-7.3%) and deodorization (9.97-8.27%) were higher than that of degumming (3.01-0.87%) and bleaching (2.75-1.18%). Deodorization affected total tocopherols contents the most, followed by bleaching, neutralization and degumming. There was a remarkable reduction in total content of phenol, β-carotene and oxygen radical absorbance of all oils during refining. The accumulated information can be used in looking for the optimum condition to meet the basic requirements for oil and minimize micronutrients losses so as to increase their market value.
Evidence from cell culture studies indicates that β-carotene-(BC)-derived apocarotenoid signaling molecules can modulate the activities of nuclear receptors that regulate many aspects of adipocyte ...physiology. Two BC metabolizing enzymes, the BC-15,15'-oxygenase (Bcmo1) and the BC-9',10'-oxygenase (Bcdo2) are expressed in adipocytes. Bcmo1 catalyzes the conversion of BC into retinaldehyde and Bcdo2 into β-10'-apocarotenal and β-ionone. Here we analyzed the impact of BC on body adiposity of mice. To genetically dissect the roles of Bcmo1 and Bcdo2 in this process, we used wild-type and Bcmo1(-/-) mice for this study. In wild-type mice, BC was converted into retinoids. In contrast, Bcmo1(-/-) mice showed increased expression of Bcdo2 in adipocytes and β-10'-apocarotenol accumulated as the major BC derivative. In wild-type mice, BC significantly reduced body adiposity (by 28%), leptinemia and adipocyte size. Genome wide microarray analysis of inguinal white adipose tissue revealed a generalized decrease of mRNA expression of peroxisome proliferator-activated receptor γ (PPARγ) target genes. Consistently, the expression of this key transcription factor for lipogenesis was significantly reduced both on the mRNA and protein levels. Despite β-10'-apocarotenoid production, this effect of BC was absent in Bcmo1(-/-) mice, demonstrating that it was dependent on the Bcmo1-mediated production of retinoids. Our study evidences an important role of BC for the control of body adiposity in mice and identifies Bcmo1 as critical molecular player for the regulation of PPARγ activity in adipocytes.
Increasing evidence has been provided for a connection between retinoid metabolism and the activity of peroxisome proliferator receptors (Ppars) in the control of body fat reserves. Two different ...precursors for retinoids exist in the diet as preformed vitamin A (all-trans-retinol) and provitamin A (β,β-carotene). For retinoid production, β,β-carotene is converted to retinaldehyde by β,β-carotene monooxygenase 1 (Bcmo1). Previous analysis showed that Bcmo1 knock-out mice develop dyslipidemia and are more susceptible to diet-induced obesity. However, the role of Bcmo1 for adipocyte retinoid metabolism has yet not been well defined. Here, we showed that Bcmo1 mRNA and protein expression are induced during adipogenesis in NIH 3T3-L1 cells. In mature adipocytes, β,β-carotene but not all-trans-retinol was metabolized to retinoic acid (RA). RA decreased the expression of Pparγ and CCAAT/enhancer-binding protein α, key lipogenic transcription factors, and reduced the lipid content of mature adipocytes. This process was inhibited by the retinoic acid receptor antagonist LE450, showing that it involves canonical retinoid signaling. Accordingly, gavage of β,β-carotene but not all-trans-retinol induced retinoid signaling and decreased Pparγ expression in white adipose tissue of vitamin A-deficient mice. Our study identifies β,β-carotene as a critical physiological precursor for RA production in adipocytes and implicates provitamin A as a dietary regulator of body fat reserves.
Keywords: beta-carotene; lipid components; lipid metabolism pathways; Saccharomyces cerevisiae Saccharomyces cerevisiae is a widely used cell factory for the production of fuels and chemicals. ...However, as a non-oleaginous yeast, S. cerevisiae has a limited production capacity for lipophilic compounds, such as beta-carotene. To increase its accumulation of beta-carotene, we engineered different lipid metabolic pathways in a beta-carotene producing strain and investigated the relationship between lipid components and the accumulation of beta-carotene. We found that overexpression of sterol ester synthesis genes ARE1 and ARE2 increased beta-carotene yield by 1.5-fold. Deletion of phosphatidate phosphatase (PAP) genes (PAH1, DPP1, and LPP1) also increased beta-carotene yield by twofold. Combining these two strategies resulted in a 2.4-fold improvement in beta-carotene production compared with the starting strain. These results demonstrated that regulating lipid metabolism pathways is important for beta-carotene accumulation in S. cerevisiae, and may also shed insights to the accumulation of other lipophilic compounds in yeast. Article Note: Yijin Zhao and Yueping Zhang contributed equally to this study. CAPTION(S): Supporting information. Byline: Yijin Zhao, Yueping Zhang, Jens Nielsen, Zihe Liu
The effect of beta‐carotene supplementation on cancer incidence has been investigated in several randomized controlled trials. The objective was to review the effect of beta‐carotene supplementation ...on cancer incidence in randomized trials by cancer site, beta‐carotene supplementation characteristics and study population. Relevant trials were retrieved by searching PubMed (up to April 2009). Authors involved in selected studies were contacted for additional information. Thirteen publications reporting results from 9 randomized controlled trials were included. Overall, no effect of beta‐carotene supplementation was observed on the incidence of all cancers combined (RR, 1.01; 95% CI, 0.98–1.04), pancreatic cancer (RR, 0.99; 95% CI, 0.73–1.36), colorectal cancer (RR, 0.96; 95% CI, 0.85–1.09), prostate cancer (RR, 0.99; 95% CI, 0.91–1.07), breast cancer (RR, 0.96; 95% CI, 0.85–1.10), melanoma (RR, 0.98; 95% CI, 0.65–1.46) and non melanoma skin cancer (RR, 0.99; 95% CI, 0.93–1.05). The incidence of lung and stomach cancers were significantly increased in individuals supplemented with beta‐carotene at 20–30 mg day−1 (RR, 1.16; 95% CI, 1.06–1.27 and RR, 1.34; 95% CI, 1.06–1.70), in smokers and asbestos workers (RR, 1.20; 95% CI, 1.07–1.34 and RR, 1.54; 95% CI, 1.08–2.19) compared to the placebo group. Beta‐carotene supplementation has not been shown to have any beneficial effect on cancer prevention. Conversely, it was associated with increased risk not only of lung cancer but also of gastric cancer at doses of 20–30 mg day−1, in smokers and asbestos workers. This study adds to the evidence that nutritional prevention of cancer through beta‐carotene supplementation should not be recommended.
•β-Carotene was encapsulated in nanoemulsions and emulsions.•Initial droplet size influenced potential biological fate of delivery systems.•Lipid digestion rate and extent increased with decreasing ...droplet size.•β-Carotene bioaccessibility increased with decreasing droplet size.
The interest in incorporating carotenoids, such as β-carotene, into foods and beverages is growing due to their potential health benefits. However, the poor water-solubility and low bioavailability of carotenoids is currently a challenge to their incorporation into many foods. The aim of this work was to study the influence of particle size on lipid digestion and β-carotene bioaccessibility using corn oil-in-water emulsions with different initial droplet diameters: large (d43≈23μm); medium (d43≈0.4μm); and small (d43≈0.2μm). There was a progressive increase in the mean particle size of all the emulsions as they passed through a simulated gastrointestinal tract (GIT) consisting of mouth, stomach, and small intestine phases, which was attributed to droplet coalescence, flocculation, and digestion. The electrical charge on all the lipid particles became highly negative after passage through the GIT due to accumulation of anionic bile salts, phospholipids, and free fatty acids at their surfaces. The rate and extent of lipid digestion increased with decreasing mean droplet diameter (small≈medium≫large), which was attributed to the increase in lipid surface area exposed to pancreatic lipase with decreasing droplet size. There was also an appreciable increase in β-carotene bioaccessibility with decreasing droplet diameter (small>medium>large). These results provide useful information for designing emulsion-based delivery systems for carotenoids for food and pharmaceutical uses.
Oral supplementation with the Age-Related Eye Disease Study (AREDS) formulation (antioxidant vitamins C and E, beta carotene, and zinc) has been shown to reduce the risk of progression to advanced ...age-related macular degeneration (AMD). Observational data suggest that increased dietary intake of lutein + zeaxanthin (carotenoids), omega-3 long-chain polyunsaturated fatty acids (docosahexaenoic acid DHA + eicosapentaenoic acid EPA), or both might further reduce this risk.
To determine whether adding lutein + zeaxanthin, DHA + EPA, or both to the AREDS formulation decreases the risk of developing advanced AMD and to evaluate the effect of eliminating beta carotene, lowering zinc doses, or both in the AREDS formulation.
The Age-Related Eye Disease Study 2 (AREDS2), a multicenter, randomized, double-masked, placebo-controlled phase 3 study with a 2 × 2 factorial design, conducted in 2006-2012 and enrolling 4203 participants aged 50 to 85 years at risk for progression to advanced AMD with bilateral large drusen or large drusen in 1 eye and advanced AMD in the fellow eye.
Participants were randomized to receive lutein (10 mg) + zeaxanthin (2 mg), DHA (350 mg) + EPA (650 mg), lutein + zeaxanthin and DHA + EPA, or placebo. All participants were also asked to take the original AREDS formulation or accept a secondary randomization to 4 variations of the AREDS formulation, including elimination of beta carotene, lowering of zinc dose, or both.
Development of advanced AMD. The unit of analyses used was by eye.
Median follow-up was 5 years, with 1940 study eyes (1608 participants) progressing to advanced AMD. Kaplan-Meier probabilities of progression to advanced AMD by 5 years were 31% (493 eyes 406 participants) for placebo, 29% (468 eyes 399 participants) for lutein + zeaxanthin, 31% (507 eyes 416 participants) for DHA + EPA, and 30% (472 eyes 387 participants) for lutein + zeaxanthin and DHA + EPA. Comparison with placebo in the primary analyses demonstrated no statistically significant reduction in progression to advanced AMD (hazard ratio HR, 0.90 98.7% CI, 0.76-1.07; P = .12 for lutein + zeaxanthin; 0.97 98.7% CI, 0.82-1.16; P = .70 for DHA + EPA; 0.89 98.7% CI, 0.75-1.06; P = .10 for lutein + zeaxanthin and DHA + EPA). There was no apparent effect of beta carotene elimination or lower-dose zinc on progression to advanced AMD. More lung cancers were noted in the beta carotene vs no beta carotene group (23 2.0% vs 11 0.9%, nominal P = .04), mostly in former smokers.
Addition of lutein + zeaxanthin, DHA + EPA, or both to the AREDS formulation in primary analyses did not further reduce risk of progression to advanced AMD. However, because of potential increased incidence of lung cancer in former smokers, lutein + zeaxanthin could be an appropriate carotenoid substitute in the AREDS formulation.
clinicaltrials.gov Identifier: NCT00345176.
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