Microbial Carotenoids Research Articles

Production of Carotenoids by Microorganisms

Carotenoids are one of the most studied groups of biologically active compounds. They have antioxidant, anti-inflammatory, anti-cancer, and coloring properties and are particularly interesting for the pharmaceutical, nutraceutical, food, feed, cosmetic, and textile industries. Rapidly growing consumer demand for natural products has led to a significant increase in research and development of opportunities for their production from natural sources. Among the sources of carotenoids of natural origin, various microorganisms are of greater interest. This mini-review briefly summarizes the information published mainly during the last decade about carotenoid-producing microorganisms, the physiological importance of carotenoids for microbial cells, and the possibilities to improve their biosynthesis. This review also describes some new approaches/directions to make biotechnological production of microbial carotenoids more efficient.

Continuous valorization of food waste and oily food waste using bacteria-pumice and bacteria-smectite nanocomposites: Alternative cell immobilization and zooplankton lifespan impact

Recycling waste into commercial products is a profitable strategy but the lifetime of immobilized cells for long-term waste treatment remains a problem. This study presents alternative cell immobilization methods for valorizing food waste (FW) and oily food waste (OFW) to microbial carotenoids and proteins. Carriers (pumice or smectite), magnetite nanoparticles, and isolated photosynthetic bacteria were integrated to obtain magnetically recoverable bacteria-pumice and bacteria-smectite nanocomposites. After recycling five batches (50 d), chemical oxygen demand removal from FW reached 76% and 78% with the bacteria-pumice and bacteria-smectite nanocomposite treatments, respectively, and oil degradation in OFW reached 71% and 62%, respectively. Destructive changes did not occur, suggesting the durability of nanocomposites. The used nanocomposites had no impact on the lifespan of Moina macrocopa or water quality as assessed by toxicity analysis. Bacteria-pumice and bacteria-smectite nanocomposites are efficient for food waste recycling and do not require secondary treatment before being discharged into the environment.

Current Advances in Carotenoid Production by Rhodotorula sp.

Microbial carotenoids are pigments of lipophilic nature; they are considered promising substitutes for chemically synthesized carotenoids in the food industry. Their benefits for human health have been demonstrated due to their antioxidant capacity. Yeasts of the genus Rhodotorula have genotypic characteristics that allow them to accumulate high concentrations of carotenes under certain stress conditions. The present review includes recent information covering different aspects of carotenoid production in Rhodotorula sp. fermentation. This review focuses on fermentation carotenoid production strategies, describing various economic raw materials as sources of carbon and nitrogen, the capacity for tolerance to heavy metals, and the effect of light, pH, and salts on the accumulation of carotenoids. Genetic modification strategies used to obtain strains with increased carotenoid production are described. Furthermore, using magnetic nanoparticles in the fermentation system, which could be a stress factor that increases pigment production, is considered for the first time. Rhodotorula is a potential source of high-value carotenoids with applications in the cosmetics, pharmaceutical, and food industries.

Carotenoid Production of Rhodosporodimum Toruloides under Light Irradiation

Carotenoids are widely used as an antioxidant, a precursor to vitamin A, and food colorants in the medical, cosmetic, chemical, food, and feed industries. They were distributed in diverse microorganisms including bacteria, algae, and fungi. Among them, the yeast Rhodosporidium toruloides is convenient for large-scale fermentation due to its unicellular nature and high growth rate. However, many factors influence the biotechnological synthesis of carotenoids. Light is a crucial consideration while making microbial carotenoids. Carotenogenic is a photo-protective technique used by microorganisms to defend themselves from the light that causes oxidative damage. R. toruloides raised their carotenoid productivity under light conditions in this study. Various lights were used to compare the effect of color light in carotenoid productivity. Results showed that R. toruloides produced more carotenoid content when cultured in blue or white light as compared to a red light or in the dark. Besides, results from microarray showed that this light influence was in the transcription gene level, the light irradiation encouraged the formation of antioxidants such carotenoids, causes a protective mechanism against DNA damage and oxidative stress.

Production of microbial carotenoid using innate inherent of the food industry wastewater

Yeast is considered as the leading participant in natural pigment production, which has a wide application in the industries relevant to food, medicine and health. This study is aimed to focus on producing carotenoids from food industry waste. The food industry waste's innate microbe (Rhodotorula mucilaginosa) is used for the bioremediation of the same waste, and it was also used as the precursor for carotenoid production. The nutritional supplement (different carbon sources) and their effect on carotenoid production were also studied in this research, revealing glucose could be a good carbon source for carotenoid production. The solvent effect on carotenoid separation was studied, which revealed that methanol, combined with ultrasonication, is the best solvent system for carotenoid extraction from Rhodotorula mucilaginosa. The batch study of this conjoint bioremediation and carotenoid production process was studied for its persuading parameters (pH, temperature, light, time and agitation) effects. The maximum carotenoid production (810 µg/g) was achieved at 72 hr with the pH 6 and 27 °C in light irradiation (White light), agitation (200 rpm) and with ethanol + ultrasonication recovery system in carotenoid extraction. HPLC, FTIR and UV analysis were performed to confirm the presence of β-carotene. The analytical studies revealed that the extracted pigment contains 32.5 % of β-carotene, 54 % of torulene and 13.5 % of torularhodin, respectively. The characteristic property of the treated water was analyzed and compared with the raw wastewater, which was also found to be within the limit for discharge and reusability. These results prove that the innate yeast of food industry wastewater could be a potential candidate for wastewater remediation and carotenoid production.

Natural Carotenoids: Recent Advances on Separation from Microbial Biomass and Methods of Analysis.

Biotechnologically produced carotenoids occupy an important place in the scientific research. Owing to their role as natural pigments and their high antioxidant properties, microbial carotenoids have been proposed as alternatives to their synthetic counterparts. To this end, many studies are focusing on their efficient and sustainable production from renewable substrates. Besides the development of an efficient upstream process, their separation and purification as well as their analysis from the microbial biomass confers another important aspect. Currently, the use of organic solvents constitutes the main extraction process; however, environmental concerns along with potential toxicity towards human health necessitate the employment of "greener" techniques. Hence, many research groups are focusing on applying emerging technologies such as ultrasounds, microwaves, ionic liquids or eutectic solvents for the separation of carotenoids from microbial cells. This review aims to summarize the progress on both the biotechnological production of carotenoids and the methods for their effective extraction. In the framework of circular economy and sustainability, the focus is given on green recovery methods targeting high-value applications such as novel functional foods and pharmaceuticals. Finally, methods for carotenoids identification and quantification are also discussed in order to create a roadmap for successful carotenoids analysis.

Effects of TiO2 and H2O2 treatments on the biosynthesis of carotenoids and lipids in oleaginous red yeast Rhodotorula glutinis ZHK

Microbial carotenoids and lipids are two groups of versatile biomolecules widely used in the food, fuel, pharmaceutical, and cosmetic industries. Rhodotorula glutinis is one of the best-known oleaginous red yeasts that has the remarkable capability to produce an assortment of valuable carotenoids and lipids. Here, the effects of different concentrations of TiO2 and H2O2 treatments on carotenoid and lipid production in R. glutinis ZHK were investigated. After 120 h of cultivation, the total amount of carotenoids was significantly increased in the TiO2 (100 mg/L: 23.165 μg/gdw, 750 mg/L: 19.65 μg/gdw) and H2O2 (5 mM: 21.51 μg/gdw, 10 mM: 118.858 μg/gdw) treatments than the control (6.099 μg/gdw). In contrast, as compared to the control, the relative abundance of total lipids was significantly decreased in the TiO2 (100 mg/L) and H2O2 (10 mM) treatments, respectively. In response to TiO2 and H2O2 stresses, the increased carotenoids were probably attributed to the down-regulated lipid biosynthesis flux, while the decreased lipids might be ascribed to the down-regulated fatty acid biosynthesis flux. Our results presented herein not only provide an effective strategy for modulating carotenoid and lipid biosynthesis in R. glutinis ZHK but also reveal the molecular foundation to further enhance their bioproductivity by molecular manipulation.

유산균 유래 C<SUB>30</SUB> 카로티노이드 소재 개발 현황 및 포스트바이오틱스 개발 가능성

Lactic acid bacteria (LAB) are well-known for their role in the food, agriculture, and health industries. The health benefits of LAB include anti-inflammatory and antioxidant protection, immunomodulatory effects, anti-obesity effects, enhanced bioavailability of bioactive compounds, and antimicrobial properties. Many LAB are well-known probiotics and certain species have been identified as carotenoid-producers, giving them a new identity as potential postbiotic sources of carotenoids, in addition to the benefits that LAB already possess. Although the most abundant microbial carotenoids have CSUB40/SUB backbones, carotenogenic genes in LAB are specific to CSUB30/SUB carotenoid synthesis. This review discusses the production and optimization of identified CSUB30/SUB carotenoids by LAB and the current status of CSUB30/SUB carotenoid-producing LAB, to establish their potential in postbiotic development. The absorption of carotenoids in the gut is also explored to better understand the applications of viable LAB-carotenoid postbiotics in fermented food products and probiotic supplements.

Microbial Carotenoid Synthesis Optimization in Goat Cheese Whey Using the Robust Taguchi Method: A Sustainable Approach to Help Tackle Vitamin A Deficiency.

The work describes the carotenoid synthesis process by Rhodotorula glutinis P4M422 using an agro-industrial waste as the substrate, seeking a biorefinery platform approach for waste utilization to produce high-value molecules. A culture medium based on goat milk whey (GMW) was optimized via the Taguchi method (L9 array). Four factors (ethanol, carbon and nitrogen source, and pH) were evaluated at three levels. The carbon and nitrogen composition were the factors dominating the process performance. Optimized conditions were validated (Urea, 0.3% w/v; pH, 4.5; ethanol, 10% v/v; glucose, 6.0%), and the carotenoid production (4075 µg/L) was almost 200% higher than when using the un-optimized process (2058 µg/L). Provitamin A carotenoids torulene, β-carotene, and γ-carotene (different proportions) were produced under all conditions. The hydrolyzed goat milk whey showed promising expectations as a low-cost source for carotenoid production by Rhodotorula glutinis P4M422. The results are important for the innovative sustainable production of carotenoid-rich matrices for different purposes (nutrition, health promotion, color) and industries (foods, nutricosmetics, nutraceuticals, feeds), notably to help to combat vitamin A deficiency.

Microbial Carotenoids Production: Strains, Conditions, and Yield Affecting Factors

Abstract The research and development of carotenoid production has a long history, and interest in this group of pigments has not decreased to this day. Six existing carotenoids are considered industrially important: astaxanthin, β-carotene, lutein, zeaxanthin, canthaxanthin, and lycopene. These carotenoids have a wide range of applications and are used as additives in food and beverages, feed, nutraceuticals, pharmaceuticals, and cosmetics products due to their bioactive and pigmentation properties. Currently, the global pigment market is dominated by chemically synthesized carotenoids. Carotenoids derived from natural sources such as plants and microorganisms are not as popular or widespread. Currently, the market of natural carotenoids is mainly represented by microalgae Haematococcus pluvialis, Dunaliella salina, Botryococcus braunii, fungus Blakeslea trispora, yeast Phaffia rhodozyma and bacteria Paracoccus carotinifaciens. These microorganisms produce astaxanthin, β-carotene, canthaxanthin, and lycopene. Several yeast and bacteria species from Rhodotorula, Sporobolomyces, Sporidiobolus, Gordonia, and Dietzia genus can potentially become sources of carotenoids on an industrial scale, but available technologies still need improving. This paper reviews strategies for increasing the competitiveness of fungal and bacterial carotenoid production. Strategies such as selecting carotenogenic strains, using low-cost substrates, stimulating the synthesis of carotenoids by adding trace elements, TCA intermediates, NaCl, H2O2, light irradiation, and optimization of fermentation conditions such as pH, temperature and aeration are considered.

Red yeasts and their carotenogenic enzymes for microbial carotenoid production.

Carotenoids are C40 isoprene-based compounds with significant commercial interests that harbor diverse bioactivities. Prominent examples of carotenoids are beta-carotene, a precursor to vitamin A essential for proper eye health, and lycopene and astaxanthin, powerful antioxidants implicated in preventing cancers and atherosclerosis. Due to their benefits to human health, the market value for carotenoids is rapidly increasing and is projected to reach USD 1.7 billion by 2025. However, their production now relies on chemical synthesis and extraction from plants that pose risks to food management and numerous biological safety issues. Thus, carotenoid production from microbes is considered a promising strategy for achieving a healthy society with more sustainability. Red yeast is a heterogeneous group of basidiomycetous fungi capable of producing carotenoids. It is a critical source of microbial carotenoids from low-cost substrates. Carotenogenic enzymes from red yeasts have also been highly efficient, invaluable biological resources for biotechnological applications. In this minireview, we focus on red yeast as a promising source for microbial carotenoids, strain engineering strategies for improving carotenoid production in red yeasts, and potential applications of carotenogenic enzymes from red yeasts in conventional and nonconventional yeasts.

4,4'-Diaponeurosporene Production as C30 Carotenoid with Antioxidant Activity in Recombinant Escherichia coli.

Carotenoids, a group of isoprenoid pigments, are naturally synthesized by various microorganisms and plants, and are industrially used as ingredients in food, cosmetic, and pharmaceutical product formulations. Although several types of carotenoids and diverse microbial carotenoid producers have been reported, studies on lactic acid bacteria (LAB)-derived carotenoids are relatively insufficient. There is a notable lack of research focusing on C30 carotenoids, the functional characterizations of their biosynthetic genes and their mass production by genetically engineered microorganisms. In this study, the biosynthesis of 4,4'-diaponeurosporene in Escherichia coli harboring the core biosynthetic genes, dehydrosqualene synthase (crtM) and dehydrosqualene desaturase (crtN), from Lactiplantibacillus plantarum subsp. plantarum KCCP11226 was constructed to evaluate and enhance 4,4'-diaponeurosporene production and antioxidant activity. The production of 4,4'-diapophytoene, a substrate of 4,4'-diaponeurosporene, was confirmed in E. coli expressing only the crtM gene. In addition, recombinant E. coli carrying both C30 carotenoid biosynthesis genes (crtM and crtN) was confirmed to biosynthesize 4,4'-diaponeurosporene and exhibited a 6.1-fold increase in carotenoid production compared to the wild type and had a significantly higher antioxidant activity compared to synthetic antioxidant, butylated hydroxytoluene. This study presents the discovery of an important novel E. coli platform in consideration of the industrial applicability of carotenoids.

Production and stability of food-grade liposomes containing microbial carotenoids from Rhodotorula mucilaginosa

We demonstrated the technical feasibility of obtaining carotenoids-loaded liposomes from soybean lecithins using an ethanol injection technique. We evaluated the influence of three lecithin-types with different phosphatidylcholine content and microbial carotenoids produced by yeast Rhodotorula mucilaginosa on liposome properties. The liposomal systems were characterized by average hydrodynamic diameter, polydispersity index, ζ-potential, and stability under different pH and heat temperature conditions commonly observed in food processing. The lecithin type and concentration used to produce liposomes significantly influence the hydrodynamic diameter, polydispersity index, and ζ-potential. In general, we observed the presence of liposomes with diameters ranging from 150 to 221 nm and a polydispersity index of approximately 0.300 when Lipoid S45 was used. The incorporation of microbial carotenoids promoted a significant increase in hydrodynamic diameter and ζ-potential, while carotenoid-loaded liposomes showed a lower polydispersity index. The carotenoid-loaded liposomes submitted to pH 3 presented a visual phase separation, while liposomes submitted at 70 °C for 15 min showed degradation of carotenoids equal to control assay (without treatment). We concluded that it is possible to incorporate microbial carotenoids in food-grade liposomal systems, allowing for further studies aimed at their application as an encapsulating and/or delivery system to be used in aqueous food products.

Transcriptomic and metabolomic analysis reveals the potential mechanisms underlying the improvement of β-carotene and torulene production in Rhodosporidiobolus colostri under low temperature treatment

Carotenoids are a group of versatile isoprenoid pigments widely utilized in the food, pharmaceutical and cosmetic industries. Rhodosporidiobolus colostri is a cold-adapted yeast that has piqued interest as a natural source of microbial carotenoids, including β-carotene, torulene and torularhodin. Here, the effect of low temperature on carotenoid production in R. colostri was investigated. The results indicated that the total carotenoid production was significantly increased at the low temperature (16 ℃) treatment (29.016 mg/L) as compared to control (25 ℃) (17.147 mg/L) after 5 days of cultivation. Among them, the increase in β-carotene and torulene serve as the main contributors to the improvement in total carotenoid production. Integrative analyses of the transcriptome and metabolome suggested that the up-regulation of the terpenoid backbone biosynthesis pathway and the down-regulation of the TCA cycle flux allow more acetyl-CoA to be diverted to carotenogenesis, which might be the reason for the increased production of β-carotene and torulene in R. colostri under low temperature treatment. Our results presented herein should not only provide an effective strategy for increasing total carotenoids production in R. colostri, but lay the molecular groundwork to further facilitate genetic engineering to enhance the yield of certain carotenoids.

A MINI REVIEW ON CAROTENOIDS FROM THERMOPHILES- STRUCTURAL FEATURES AND ITS BIOLOGICAL ADVANTAGES

Microbial carotenoids offer several advantages such as ready accessibility and reproducibility than plants, with no seasonal-dependence to limit their availability. The carotenoid producing microbes are found in varied sources, of which, those isolated from extremophilic conditions show intense coloration and their resistance to extreme conditions makes them valuable during industrial production. The present review focuses on the core structural features and the possible modifications in carotenoids from thermophiles that renders functionality and survival advantage thus making them best candidate for future applications.

Recent development in the production strategies of microbial carotenoids.

Carotenoids are a diverse group of lipid-soluble pigments that exhibit potent biological activities such as antioxidant, anti-inflammatory, and provitamin A activities. The potent health benefits of carotenoids result in the surge in the market demands for carotenoids, especially natural carotenoids from sustainable sources. Microbial carotenoids have attracted considerable interests for many industrial applications because of the low costs and ease of scaling-up with shorter production time. There is a growing interest in the search of new and sustainable microbial sources and cost-efficient production strategies following the high economical values and vast commercial applications of carotenoids. This article presents a review on the industrial production strategies of microbial carotenoids from microalgae, fungi, and bacteria sources. The industrial significance of the mass production of microbial carotenoids is also discussed. The structure, classification, and biosynthesis pathway of the carotenoids are also presented in this review.

Carotenoid Production by Rhodosporidium paludigenum Using Orange Peel Extract as Substrate

Carotenoids are fat-soluble pigments that have various benefits in health and beauty. The demand and market of carotenoids are increasing; thus, the faster and cheaper biological production of these pigments using microorganisms is desired. In this study, the optimum medium pH and nitrogen concentration for carotenoid production by Rhodosporidium ( R. ) paludigenum using orange peel extract as substrate were determined. The soluble sugars from orange peels were extracted using distilled water at 100 °C. The yeast inoculum was cultivated in Yeast Peptone Dextrose (YPD) media before fermentation. The independent variables in the fermentation factorial design included initial medium pH (5; 6; and 7) and nitrogen concentration (0; 1; and 1.75 g/L urea in the medium). The decrease in reducing sugar concentration and the increase in biomass dry weight during fermentation demonstrated carbon source consumption by R. paludigenum for growth and carotenoid production. On the sixth day of fermentation (D6), the culture was harvested for the total carotenoid extraction and determination. The highest total carotenoid yield (107.63 µg/g) was achieved by the treatment group with an initial medium pH of 6 without nitrogen supplementation. This result indicated the orange peel extract potential as a substrate for carotenoid production using R. paludigenum as a workhorse. This was the first reported research in natural carotenoid generation using R. paludigenum (strain InaCC Y-236) locally isolated in Indonesia as the producer and orange peel extract as the substrate. Thus, this research would enrich the microbial carotenoid exploration and waste valorization to value-added products at the same time. The study can then be developed further and upscaled for industrial applications.Â

Carotenoid Production by Red Yeast Isolates Grown in Agricultural and "Mandi" Waste

Microbial synthesis of carotenoids has gained interest as an alternative to synthetic carotenoid production due to its easy extraction and high yield. The current study investigates the usability of fruit and vegetable waste- ‘mandi’ waste and agricultural waste as growth medium for carotenoid production by different isolated yeast strains. In this study, five isolated yeast strains were identified which were able to utilize C5 and C6 sugars. These yeast strains were compared for their carotenoid production and growth properties when cultivated in inexpensive growth media such as, vegetable ‘mandi’-waste and paddy straw hydrolysate (agricultural waste). During the cultivation, optical density (600 nm), cell weight (wet biomass and dry biomass), total sugar and reducing sugar in selected culture media were determined at different time intervals. The microbial carotenoids were extracted in DMSO (Dimethyl sulfoxide) and were finally transferred to hexane for separation by liquid–liquid extraction. Using ‘mandi’-waste hydrolysate (waste extract), the strains gave best results with biomass ranging from 29 ± 0.18 to 54 ± 0.14 g/L and the maximum carotenoid produced ranged between 38 ± 0.8 and 62 ± 0.93 mg/L. Based on our results, ‘Mandi’ waste hydrolysate was found to be the most potent source for carotenoid production. This report provides a suitable bioprocess for the production of yeast-carotenoids, using vegetable ‘mandi’ waste (waste extract) and agricultural waste hydrolysates (paddy straw hydrolysate) via sustainable and cost-effective strategy that may be scaled up in future.

In vivo creation of plasmid pCRT01 and its use for the construction of carotenoid-producing Paracoccus spp. strains that grow efficiently on industrial wastes

BackgroundCarotenoids are natural tetraterpene pigments widely utilized in the food, pharmaceutical and cosmetic industries. Currently, chemical synthesis of these compounds outperforms their production in Escherichia coli or yeast due to the limited efficiency of the latter. The use of natural microbial carotenoid producers, such as bacteria of the genus Paracoccus (Alphaproteobacteria), may help to optimize this process. In order to couple the ability to synthesize these pigments with the metabolic versatility of this genus, we explored the possibility of introducing carotenoid synthesis genes into strains capable of efficient growth on simple low-cost media.ResultsWe constructed two carotenoid-producing strains of Paracoccus carrying a new plasmid, pCRT01, which contains the carotenoid synthesis gene locus crt from Paracoccus marcusii OS22. The plasmid was created in vivo via illegitimate recombination between crt-carrying vector pABW1 and a natural “paracoccal” plasmid pAMI2. Consequently, the obtained fusion replicon is stably maintained in the bacterial population without the need for antibiotic selection. The introduction of pCRT01 into fast-growing “colorless” strains of Paracoccus aminophilus and Paracoccus kondratievae converted them into efficient producers of a range of both carotenes and xanthophylls. The exact profile of the produced pigments was dependent on the strain genetic background. To reduce the cost of carotenoid production in this system, we tested the growth and pigment synthesis efficiency of the two strains on various simple media, including raw industrial effluent (coal-fired power plant flue gas desulfurization wastewater) supplemented with molasses, an industrial by-product rich in sucrose.ConclusionsWe demonstrated a new approach for the construction of carotenoid-producing bacterial strains which relies on a single plasmid-mediated transfer of a pigment synthesis gene locus between Paracoccus strains. This strategy facilitates screening for producer strains in terms of synthesis efficiency, pigment profile and ability to grow on low-cost industrial waste-based media, which should increase the cost-effectiveness of microbial production of carotenoids.

Photoprotective nanoemulsions containing microbial carotenoids and buriti oil: Efficacy and safety study

Photoprotective nanoemulsions are able to attenuate skin damage from overexposure to the sun, thus avoiding the immediate effects caused by ultraviolet radiation. The global cosmetics market understands that there is a demand and greater acceptance by consumers for formulations containing natural products compatible with the skin. Consequently, there is an increasingly need to develop such products that are safe and effective. Furthermore, there is a growing interest in nanoemulsions (NE) in the pharmaceutical industry, due the versatility of incorporating lipophilic substances into cosmetic formulations. In the present work, oil-in-water photoprotective nanoemulsions containing microbial carotenoids, buriti oil and chemical filters were developed and characterized. The essential physical properties of the droplets, the transmission electronic microscopy (TEM), the sun protection factor (SPF) as well as the stability of the formulations were determined. In vitro phototoxicity was evaluated using Balb 3 T3 with relative cell viability estimated by Neutral Red Uptake, with the Photo Irritation Factor (PIF) and the Medium Photo Effect Factor (MPF) as the measurement parameters. Nanoemulsion 3 (NE3) showed spherical morphology with an average droplet size of 142.11 ± 0.92 nm and polydispersity index (PDI) of 0.198 ± 0.017. This nanoemulsion containing microbial carotenoids and buriti oil exhibited a SPF of 36 ± 1.5. Neutral Red Uptake revealed that the cells kept their viability even after irradiation and those nanoemulsions containing the microbial carotenoids and buriti oil were not phototoxic. The addition of microbial carotenoids and buriti oil in nanoemulsions was positive in increasing the mean SPF values compared to the control formulation.