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Exopolysaccharides (EPS) produced by diazotrophic bacteria are promising biomolecules with commercial potential; however, effects of cultivation conditions on their yield have remained underexplored. This study aimed to maximize EPS production by Mesorhizobium sp. SEMIA 816 in whey permeate (WP) as the carbon source. A Plackett–Burman (PB) design was applied to assess the impact of 12 variables, namely K?HPO?, KH?PO?, MgSO?·7H?O, NaCl, yeast extract (YE), MnCl?·4H?O, CaCl?·2H?O, WP, pH, medium-to-reactor volume ratio (VM:VR), agitation and temperature, on EPS and biomass concentrations. EPS production ranged from 0 to 9.28 g L-1; the WP concentration exerted the most positive influence. Biomass production ranged from 0.6 to 7.15 g L-1; YE exerted the greatest effect, although it was negatively correlated with EPS production. Maximum EPS concentration (9.28 g L-1) was achieved after 96 h under the central point conditions of the experimental design, whereas the highest biomass concentration (7.15 g L-1) was reached after 72 h under a different set of conditions. Agitation and temperature influenced both responses negatively, a fact that highlighted the need to control them precisely. This study provides insights into the maximization of EPS production since it shows the potential of WP as an effective carbon source and identifies key factors affecting both EPS and biomass yields.

The yeast Phaffia rhodozyma is known for producing carotenogenic pigments, commonly used in aquaculture feed formulation as well as in cosmetic, pharmaceutical, and food industries. Despite the high production of carotenoids from microorganisms by biotechnology, their use has limitation due to the cell wall resistance, which constitutes a barrier to the bioavailability of carotenoids. Therefore, there is a need to improve carotenoids recovering technique from microorganisms for the application of food industries. This study aimed to compare mechanical, chemical, and enzymatic techniques of cell disruption for extracting carotenoids produced by P. rhodozyma NRRL Y-17268. Among the techniques studied, the highest specific concentration of carotenoids (190.35 μg/g) resulted from the combined techniques of frozen biomass maceration using diatomaceous earth and enzymatic lysis at pH of the reaction medium of 4.5 at 55°C, with initial activity of β-1,3 glucanase of 0.6 U/mL for 30 min.

Search for naturally grown food has stimulated the biotechnological production of carotenoids. Therefore, the use of the yeast has been researched due to its abilities to assimilate different sources as substrates and to produce high amounts of carotenoids. Furthermore, alternative sources have been used as the culture medium to reduce costs and environmental impact. A potent carotenoid is astaxanthin in view of its health-promoting and antioxidative properties. It consists of different geometrical isomers with and configuration. In this carotenoid is mostly found in the form, but isomers can also be found. Carotenoid production was investigated in culture medium containing by-products such as raw glycerol (from biodiesel) and parboiled rice effluent. The effects of the culture medium components on biomass concentration and specific and volumetric productions of carotenoids were verified by the Plackett-Burman design. Cultivations were carried out with yeast NRRL Y-17268 at 25 °C and 150 rpm for 168 h. In this study, maximum production of carotenoids was obtained under the following conditions (in g/L): raw glycerol 10, glucose 10, yeast extract 10, malt extract 10 and peptone 1 at pH=6. Resulting specific and volumetric productions of carotenoids were 326.8 and 4.1 µg/g, respectively.

Carotenoids are natural pigments that can be produced through biotechnological processes. However, the costs are relatively high and can be minimized by using lower-cost substrates as alternative nutrient sources. The fed-batch fermentation is one of the techniques used to obtain a high biomass concentration and/or maximum production. Thus, the aim of this work is to produce carotenoids in batch and fed-batch fermentation with the yeast Rhodotorula mucilaginosa CCT 7688 using agroindustrial byproducts in the culture medium. Carotenoid production was increased using experimental designs, which modified the concentration of the agroindustrial medium. In batch production the highest concentrations of total carotenoids (1248.5 μg/L) and biomass (7.9 g/L) were obtained in the medium containing 70 g/L sugar cane molasses and 3.4 g/L corn steep liquor at 25 °C and 180 rpm in 168 h, demonstrating an increase of 17 % when compared to the standard yeast malt medium (1200 μg/L). In the fed-batch production, different feeding strategies were tested with 30 g/L sugar cane molasses and 6.5 g/L corn steep liquor, reaching a total carotenoid production of 3726 μg/L and biomass concentration of 16 g/L. Therefore, the strategy of the fed-batch process resulted in an increase in the carotenoid production of approx. 400 % compared to that in the batch process (740.3 μg/L). Thus, the R. mucilaginosa strain has the potential to produce carotenoids in agroindustrial medium.

This study focuses on the potential of Rhodotorula mucilaginosa CCT 7688 in simultaneous production of lipids and carotenoids in agroindustrial byproduct-based media and specially aims at establishing a process condition that guarantees high concentrations of both bioproducts, i.e., a carotenoid-rich microbial oil with potential economic value and health benefits attributed to carotenoids and fatty acids. Four different combinations of cultivation modes (batch and fed-batch) and alternative substrates (crude glycerol, sugarcane molasses and corn steep liquor) were tested. The M2-B assay, which comprises the use of an agroindustrial byproduct-based medium without any supplementation (70 g L −1 sugarcane molasses and 3.4 g L −1 corn steep liquor) and batch mode, was selected as the most promising one to produce both compounds. Total carotenoid production and total lipid content were 1794.2 µg L −1 and 43.2% (w/w), respectively, after 144 h of cultivation. The fatty acid profile showed predominance of oleic acid (69.9%) and palmitic acid (23.2%). Thus, R. mucilaginosa CCT 7688 may be used in simultaneous production of lipids and carotenoids successfully; its fatty acid profile is similar to that found in olive oil. Both compounds are economically interesting and have great possibility of future commercial applications.

Response surface methodology was used to determine optimum conditions for the esterification of ethanol and butyric acid to produce a flavour ester using immobilized lipase. Various reaction parameters including butyric acid concentration, enzyme concentration, temperature and ethanol/butyric acid molar ratio affecting ethyl butyrate production were investigated using a fractional factorial design [2.sup.4-1]. Based on the results from the first factorial design, all of the variables which were significant in the process were selected to be used in a [2.sup.4] central composite rotatable design (CCRD). The optimum conditions for the enzymatic reaction were obtained at a 90 mM butyric acid concentration using a 7.7 g/L enzyme concentration at 45°C and the ethanol/butyric acid molar ratio of 1.1 for 3 h. The esterification percentage, under these conditions, was 87 %. Key words. ethyl butyrate, immobilized lipase, esterification, optimization, enzymatic synthesis

Background: Nanotechnology provides innovative strategies to enhance drug delivery and therapeutic efficacy through advanced nanocarrier systems. Objectives: This study aimed to develop and optimize a nanostructured lipid carrier (NLC) co-encapsulating curcumin (CUR) and resveratrol (RESV) using a fractional factorial design to develop a topical formulation with antioxidant and anti-inflammatory properties. Methods: NLCs were produced via hot emulsification followed by high-pressure homogenization, and their physicochemical characteristics, drug content, stability, release profile, antioxidant activity, skin delivery, and cellular compatibility were evaluated. Results: The optimized formulation exhibited an average particle size of approximately 300 nm, a polydispersity index below 0.3, and high drug loading for both compounds. Stability studies over 90 days revealed no significant changes in physicochemical parameters, confirming the formulation’s robustness. In vitro release assays demonstrated sustained release of both actives, with 58.6 ± 2.9% of CUR and 97 ± 3% of RESV released after 72 h. Antioxidant activity, assessed by the DPPH and ABTS assays, showed concentration-dependent radical-scavenging effects, indicating antioxidant potential. Skin permeation/retention experiments using porcine skin showed enhanced retention of CUR and RESV within the tissue, with no detectable permeation, indicating suitability for topical delivery. In addition, in vitro cell assays using human keratinocytes showed concentration-dependent responses and acceptable cellular compatibility. Conclusions: Overall, this study demonstrates the successful application of nanotechnology and experimental design to develop stable and efficient lipid-based nanocarriers containing natural polyphenol for topical therapy targeting oxidative and inflammatory skin disorders.

This study was aimed at evaluating the effects of light-emitting diode (LED) (blue, green, red, and white) on carotenoid and lipid production by Rhodotorula mucilaginosa CCT 7688. Results showed that LED at 50 µmol m−2 s−1 enhanced carotenoid production in all colors under study, by comparison with the control (1794.21 µg L−1). However, both green (3473.00 µg L−1) and red (3497.76 µg L−1) stood out in the production since there was increase of 93.5 and 94.9%, respectively. β-Carotene and astaxanthin were found to be the major carotenoids. However, at intensity of 100 µmol m−2 s−1, there was decrease (green 1377.0 µg L−1; red 826.86 µg L−1). In lipid production, there was no significant change when 50 µmol m−2 s−1 was used. The yeast exhibited distinct behavior towards the LED; i.e., carotenogenic production was notably more accentuated, a fact that shows that adequate illumination is an effective strategy to increase carotenoid production. In this sense, it is concluded that the intensity of light and colors applied to microbial cultivation is extremely important, as it affects the metabolism of yeasts, leading to an increase in the production of carotenoids and causing a significant change in the profile of fatty acids produced.

This study aimed to evaluate different methods of recovery of carotenoid-rich microbial oil (CRMO) produced by Rhodotorula mucilaginosa in renewable agro-industrial by-products to achieve oleogels based on CRMO and carnauba wax (CW). Among the oil extraction methods, Bligh and Dyer was selected since this system kept color stability. Extracted CRMO showed 41.1 µg g −1 of total carotenoid and lipid content of 23.8%. Oleogels based on CRMO or olive oil (control system) and CW at concentrations of 2.5, 5, 7.5, and 10% were characterized and their potential application to food systems was highlighted. This study is one of the first to describe production of oleogel based on CRMO. Its results contribute to its potential as a fat replacer. This novel oleogel may meet worldwide demands to reduce trans fatty acids in foods and act as a protective system of bioactive biocompounds.

Biosurfactant are surface active compounds with emulsifying capacity and are produced by microorganisms, and they may be affected by factors related to microbial cultivation, such as pH, salinity, incubation time, carbon and nitrogen sources. The aim of this work was to study the influence of the culture conditions on the production of biosurfactants by Phialemonium sp using agroindustrial wastes. The processing parameters of temperature, humidity and pH produced the most significant effects on the production of biosurfactant and emulsifying activity. The maximum concentration of biosurfactant obtained in this study was equivalent to a surface tension reduction of 8.5 mg L-1 surfactin commercial solution using wheat bran, pH of 4.5, and 0.5% of soybean oil added at 30°C. Under these conditions, 83.4 EU g-1 of emulsifying activity, 16.4 g L-1 of emulsifier index and 18.3 U g-1 lipolytic capacity were obtained.