Improved production of lycopene and β-carotene by Blakeslea trispora with oxygen-vectors

Lycopene and β-carotene production were increased when oxygen-vectors, n-hexane and n-dodecane, were added to cultures of Blakeslea trispora because of the enhanced dissolved oxygen concentrations. With 1% (v/v) n-hexane or n-dodecane added in the medium, lycopene production was 51% or 78% higher and β-carotene production was 44% or 65% higher than that of the control, respectively. The highest lycopene and β-carotene production, 533 mg l⁻¹and 596 mg l⁻¹, were obtained when 1% (v/v) n-dodecane and 0.1% (w/v) Span 20 were added together, which were 2.1-fold and 1.8-fold of the control, respectively.     

Strain selection for β-carotene production by Dunaliella

Four strains of Dunaliella were grown at 25°C and pH 8±0.5, with continous illumination at 200 W/m². Their maximum specific growth rates ranged from 0.093 day^-1 to 0.234 day^-1, nitrate yields from 3.0 to 7.8 g cells/g NaNO₃ and lipid contents from 3% to 6% of the dry wt, with carotenes 50 to 80% of the lipids. Of the carotenes, -carotene made up 7 to 19%; all-trans--carotene 32 to 52% and 9-cis--carotene 29 to 55%. There are, therefore, considerable intra-specific differences between strains of Dunaliella.     

Influence of areal density on β-carotene production by Dunaliella salina

High irradiance is probably the most important factor responsible for the massive accumulation of β-carotene by the halotolerant green alga Dunaliella salina. Operating outdoor cultures at optimal areal densities should result in maximal productivity. It is known that the optimal areal density is not fixed for all algae, where it could vary depending on the type of algae cultured, pond construction, turbulence and prevailing environmental conditions. At biomass concentrations below the optimum, more light per cell is available than that which could be absorbed by the biomass. These high light conditions should favour carotenogenesis and could result in higher β-carotene production rates. The results obtained clearly showed that over and above light and nutrient stress, an extremely important aspect is the residence time of the cells in the ponds. Longer residence times resulted in the development of larger cells, containing larger quantities of β-carotene. Productivity of biomass and β-carotene were about 70% higher at areal densities of 35–45 g m^-2, compared to areal densities of 15–25 g m^-2.     

Exploitation of Dunaliella for β-carotene production

Halotolerant microalga Dunaliella, which is exploited for the production of dried biomass or cell extract, is used as a medicinal food. With the advancement in this field in recent years, the production of bio-organic compounds such as β-carotene is established in many countries. Large-scale production of β-carotene is controlled by numerous stress factors like high light intensity, high salinity, temperature and availability of nutrients. The state-of-the-art strategies in industries in closed systems under new set of inductive factors will additionally promote the ease of commercial production of β-carotene. This review mainly focuses on the different methodologies employed recently for the optimum production of β-carotene from Dunaliella species.     

Simultaneous production of high activities of thermostable endoglucanase and β-glucosidase by the wild thermophilic fungus Thermoascus aurantiacus

The culture-medium composition was optimised, on a shake-flask scale, for simultaneous production of high activities of endoglucanase and β-glucosidase by Thermoascus aurantiacus using statistical factorial designs. The optimised medium containing 40.2 g l⁻¹ Solka Floc as the carbon source and 9 g l⁻¹ soymeal as the organic nitrogen source yielded 1130 nkat ml⁻¹ endoglucanase and 116 nkat ml⁻¹β-glucosidase activities after 264 h as shake cultures. In addition, good levels of β-xylanase (3479 nkat ml⁻¹) and low levels of filter-paper cellulase, β-xylosidase, α-l-arabinofuranosidase, β-mannanase, β-mannosidase, α-galactosidase and β-galactosidase were detected. Batch fermentation in a 5-l laboratory fermentor using the optimised medium allowed the production of 940 nkat ml⁻¹ endoglucanase and 102 nkat ml⁻¹β-glucosidase in 192 h. Endoglucanase and β-glucosidase showed optimum activity at pH 4.5 and pH 5, respectively, and they displayed optimum activity at 75 °C. Endoglucanase and β-glucosidase showed good stability at pH values 4–8 and 4–7, respectively, after a prolonged incubation (48 h at 50 °C). Endoglucanase had half-lives of 98 h at 70 °C and 4.1 h at 75 °C, while β-glucosidase had half-lives of 23.5 h at 70 °C and 1.7 h at 75 °C. Alkali-treated bagasse, steam-treated wheat straw, Solka floc and Sigmacell 50 were 66, 48.5, 33.5 and 14.4% hydrolysed by a crude enzyme complex of T. aurantiacus in 50 h. Received: 12 November 1999 / Accepted: 14 November 1999     

Maternal-fetal transfer and metabolism of vitamin A and its precursor β-carotene in the developing tissues

The requirement of the developing mammalian embryo for retinoic acid is well established. Retinoic acid, the active form of vitamin A, can be generated from retinol and retinyl ester obtained from food of animal origin, and from carotenoids, mainly β-carotene, from vegetables and fruits. The mammalian embryo relies on retinol, retinyl ester and β-carotene circulating in the maternal bloodstream for its supply of vitamin A. The maternal-fetal transfer of retinoids and carotenoids, as well as the metabolism of these compounds in the developing tissues are still poorly understood. The existing knowledge in this field has been summarized in this review in reference to our basic understanding of the transport and metabolism of retinoids and carotenoids in adult tissues. The need for future research on the metabolism of these essential lipophilic nutrients during development is highlighted. This article is part of a Special Issue entitled: Retinoid and Lipid Metabolism.     

Copper status in rats fed diets supplemented with either vitamin E,vitamin A,or β-carotene

Copper status was measured in rats fed copper-adequate, purified diets supplemented with either vitamin E (250 IU/kg), vitamin A (40,000 IU/kg), or β-carotene (2 g/kg). It was hypothesized that the extra intake of the antioxidants would spare vitamin C resulting in a decreased copper status as shown previously after supplementation with vitamin C. A significant increase in plasma ascorbate concentration was observed after β-carotene supplementation, but not after supplemental vitamin E or vitamin A. Extra intake of either β-carotene or vitamin A slightly, but significantly, raised plasma copper concentrations. β-carotene also slightly raised liver copper concentration. Supplemental vitamin E had no effect on plasma and liver copper concentrations. It is concluded that the observed relatively small effects of supplemental vitamin A and β-carotene on copper status in rats are not mediated by changes in plasma vitamin C concentration.     

Simultaneous production of α-arabinofuranosidase and xylanase by Termitomyces clypeatus

Termitomyces clypeatus produced xylanase and -L-arabinofuranosidase simultaneously in various media. The arabinofuranosidase had pH and temperature optima of 5.5 and 50°C, respectively, and was stable at 50°C for 30 min and at pH values from 2 to 5. The partially purified enzyme was distinct from xylanase present in the same medium.The authors are with the Department of Applied Biochemistry, Indian Institute of Chemical Biology, 4 Raja S.C. Mullick Road, Calcutta 700 032, India     

Metabolic engineering of the terpenoid biosynthetic pathway of Escherichia coli for production of the carotenoids β-carotene and zeaxanthin

Metabolic engineering of the early non-mevalonate terpenoid pathway of Escherichia coli was carried out to increase the supply of prenyl pyrophosphates as precursor for carotenoid production. Transformation with the genes dxs for over-expression of 1-deoxy-d-xylulose 5-phosphate synthase, dxr for 1-deoxy-d-xylulose 5-phosphate reductoisomerase and idi encoding an isopentenyl pyrophosphate stimulated carotenogenesis up to 3.5-fold. Co-transformation of idi with either dxs or dxr had an additive effect on ß-carotene and zeaxanthin production which reached 1.6 mg g^–1 dry wt.     

Production of β-carotene by aRhodotorula strain

Summary The production of -carotene by the biomass ofRhodotorula strain var.glutinis, during the stationary phase of growth and in non-proliferating conditions was assayed. When the cells were transferred to distilled water, the fraction of -carotene produced increased from 130 to 630 g per gram of dried cells.     

Effective production of retinal from β-carotene using recombinant mouse β-carotene 15,15′-monooxygenase

The gene encoding β-carotene 15,15′-monooxygenase from Mus musculus (house mouse), which cleaves β-carotene into two molecules of retinal, was cloned and expressed in Escherichia coli. The expressed enzyme was purified by His-tag affinity and resource Q ion exchange chromatography columns to a final specific activity of 0.51 U mg⁻¹. The optimum pH, temperature, substrate and detergent concentrations, and enzyme amount for effective retinal production were determined to be 9.0, 37°C, 200 mg l⁻¹ β-carotene, 5% (w/v) Tween 40, and 0.2 U ml⁻¹ enzyme, respectively. Under optimum conditions, the recombinant enzyme produced 72 mg l⁻¹ retinal in a 15-h reaction time, with a conversion yield of 36% (w/w). The specific activity of the purified enzyme and retinal production obtained in the present study were the highest results ever reported.     

Effects of cold stress on juvenile Piaractus mesopotamicus and the mitigation by β-carotene

This study investigated the effects of cold stress on morphometrical and hematological biomarkers, energy metabolism, and oxidative stress in different tissues of P. mesopotamicus, and the protective role of β-carotene. Fish were fed with a control diet (CD) and the same diet supplemented with 105 mg/kg β-carotene (BD) for 60 days. After the feeding trial, fish fed CD or BD diets were exposed to control (24 °C) and low temperature (14 °C) for 24 h. Fish (CD and BD) exposed to thermal stress showed lower hepatosomatic index. The hemoglobin increased only in CD-fed fish exposed to 14 °C. Increased glycemia, plasmatic protein depletion, and decreased hepatic glycogen were observed in fish fed the CD, while only the lipid levels in liver were augmented in BD-fed fish exposed at 14 °C. Regarding the oxidative stress, increased antioxidant enzymes activity and lipid peroxidation were observed in CD-fed fish exposed to cold. The two-way ANOVA showed an interaction between dietary treatment and temperature for glucose and oxidative stress biomarkers, with the highest values recorded in 14 °C-exposed fish fed with the CD. Our study demonstrated that cold stress had the greatest impact on fish oxidative status, and β-carotene reduces harmful effects induced by cold in P. mesopotamicus.     

Simultaneous production of endoglucanase and β-glucosidase using synthetic two cistron genes

Summary Simultaneous production of endoglucanase and -glucosidase by using a synthetic two cistron system inEscherichia coli was attempted as a possible way of reducing production cost. The first cistron in this system we constructed is an endoglucanase gene fused to a tac promoter that provides for efficient expression. The second cistron is a -glucosidase structural gene. A ribosome binding site sequence of 33-base was inserted between the two cistron genes.E. coli cells transformed with the system produced 12.4 units/mg protein of endoglucanase and 327 units/mg protein of -glucosidase, which represent 15% and 22% of total cellular protein, respectively, in L medium within three hours after induction with IPTG.     

Improved β-carotene production of Rhodotorula glutinis in fermented radish brine by continuous cultivation

Fermentation kinetics of growth and β-carotene production by Rhodotorula glutinis DM28 in batch and continuous cultures using fermented radish brine, a waste generated from fermented vegetable industry, as a cultivation medium were investigated. The suitable brine concentration for β-carotene production by R. glutinis DM28 was 30 g l^?1. Its growth and β-carotene production obtained by batch culture in shake flasks were 2.2 g l^?1 and 87 μg l^?1, respectively, while, in a bioreactor were 2.6 g l^?1 and 186 μg l^?1, respectively. Furthermore, its maximum growth rate and β-carotene productivity in continuous culture obtained at the dilution rate of 0.24 h^?1 were 0.3 g l^?1 h^?1 and 19 μg l^?1 h^?1, respectively, which were significantly higher than those in the batch. Therefore, improved growth rate and β-carotene productivity of R. glutinis in fermented radish brine could be accomplished by continuous cultivation.     

Absolute configuration of β,γ-carotene and biosynthetic implications

Racemic γ-ionone, partly resolved via its menthydrazone, was used for total synthesis of β,γ-carotene enriched in the 6′R and 6′S enantiomers. By CD correlation with natural β,γ-carotene isolated from Caloscypha fulgens 6′S-chirality is demonstrated for the natural carotene. Biosynthetic implications regarding the cyclization reaction are discussed.     

Improved β-carotene production by oxidative stress in Blakeslea trispora induced by liquid paraffin

When 3 % (v/v) liquid paraffin was added to the medium, β-carotene production increased from 397 to 715 mg l^?1 in mated cultures of Blakeslea trispora. Liquid paraffin also enhanced the oxygen concentration and induce high oxidative stress, as observed by the increase in activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). After 84 h of cultivation in the presence of liquid paraffin, the activities of SOD, CAT and POD in B. trispora increased 77, 52.5 and 76.6 %, respectively.     

Simultaneous hydrolysis of cheese whey and lactulose production catalyzed by β-galactosidase from Kluyveromyces lactis NRRL Y1564

Bioprocess and Biosystems Engineering - β-Galactosidase was produced by the yeast Kluyveromyces lactis NRRL Y1564 in cheese whey supplemented with yeast extract under the optimal temperature...     

The role of β-carotene and vitamin A in atherogenesis: Evidences from preclinical and clinical studies

Atherosclerotic cardiovascular disease (ASCVD) is the principal contributor to myocardial infarction, the leading cause of death worldwide. Epidemiological and mechanistic studies indicate that β-carotene and its vitamin A derivatives stimulate lipid catabolism in several tissues to reduce the incidence of obesity, but their roles within ASCVD are elusive. Herein, we review the mechanisms by which β-carotene and vitamin A modulate ASCVD. First, we summarize the current knowledge linking these nutrients with epidemiological studies and lipoprotein metabolism as one of the initiating factors of ASCVD. Next, we focus on different aspects of vitamin A metabolism in immune cells such as the mechanisms of carotenoid uptake and conversion to the vitamin A metabolite, retinoic acid. Lastly, we review the effects of retinoic acid on immuno-metabolism, differentiation, and function of macrophages and T cells, the two pillars of the innate and adaptive immune response in ASCVD, respectively.This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.