Assessment of Cell Disruption and Carotenoids Extraction from Sporidiobolus salmonicolor (CBS 2636)

The increasing demand for carotenoids by industries has drawn attention to their bio-production. Since pigments are intracellular, extraction steps are then needed after cell cultivation. In this work, different strategies for extraction of carotenoid pigments from Sporidiobolus salmonicolor (CBS 2636) were studied. Different solvents (dimethyl sulfoxide, petroleum ether, hexane, ethyl acetate, chloroform, and acetone), liquid N₂, and diatomaceous earth were used to disrupt the cell and thus release the intracellular carotenoids. The results of this study showed that when multiple solvents were used, a synergistic effect on the extent of carotenoids recovery was obtained. Maximum concentration of total carotenoids (913 μg/L) was obtained in the treatment using liquid N₂ and dimethyl sulfoxide to disrupt the cell, followed by the extraction with a solution of acetone/methanol (7:3, v/v).     

Evaluation of aeration and substrate concentration on the production of carotenoids by <Emphasis Type="Italic">Sporidiobolus salmonicolor</Emphasis> (CBS 2636) in bioreactor

This study aimed at optimising the cultivation conditions for the production of carotenoids by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor. The maximum content of total carotenoids in the full factorial design 22 was 3131.3 μg/L in synthetic medium with 80 g/L of glucose, 15 g/L of peptone, 5 g/L of malt extract, aeration of 1.5 vvm, agitation of 180 rpm, initial pH of 4.0 at 25 °C. In the kinetic study, we could observe that the bioproduction of carotenoids is associated with cell growth in the exponential phase, and the average specific growth (μ) in bioreactor is 0.046 h⁻¹ with a maximum yield of 0.19 g cells/L h. The maximum yield of carotenoids (60.0 μg/Lh) is observed at 50-h bioproduction. The conversion factor for total organic carbon (TOC) in cells (Y_X/_SCOT) was 2.97 g/g (0–50 h) and 0.254 g/g (50–100 h), the conversion factor glucose into cells (Y_X/Sglicose) was 0.168 g/g (0–100 h). The specific production of carotenoids (Y_P/_X) was 390 μg of carotenoids per gram of cells, the conversion factor of carbon in the product (Y_P/SCOT) was 107.8 μg/g (0–50 h) and 34.4 μg/g (50–100 h), whereas the factor Y_P/_Sglicose was 69.59 μg/g. The agitation and aeration provided better homogeneity in the culture medium, and hence greater availability of nutrients and oxygen, leading to higher production of carotenoids.     

Picosecond Capture of Photoexcited Electrons Improves Photovoltaic Conversion in MAPbI3:C70‐Doped Planar and Mesoporous Solar Cells

In this work, solar cells based on methylammonium lead iodide (MAPbI₃) doped in solution with C₇₀ fullerene in a mesoporous as well as planar electron‐transporting layer (ETL)‐free architecture are realized, showcasing in the latter case a record efficiency of 15.7% and an improved open‐circuit voltage (V_OC). Contrary to the bulk heterojunction previously reported, the C₇₀ molecules do not phase segregate and they are rather finely dispersed in the perovskite film, possibly infiltrating at the grain boundaries, while assisting the growth of a highly uniform perovskite layer. By means of time‐resolved femtosecond‐to‐nanosecond optical spectroscopy, with an extended spectral coverage, it is observed that electrons photogenerated in the perovskite are transferred to C₇₀ with a time constant of 20 ps. Despite being captured by C₇₀, electrons are not deeply trapped and can potentially bounce back into the perovskite, as suggested by the high fill factor and enhanced V_OC of the MAPbI₃:C₇₀ solar cells, especially in the case of the ETL‐free device configuration.     

Study of the bio‐production of carotenoids by Sporidiobolus salmonicolor (CBS 2636) using pre‐treated agro‐industrial substrates

BACKGROUND: The increasing industrial demand for carotenoids has aroused interest in their bio‐production, and the need to reduce production costs has encouraged the use of low cost industrial substrates, such as agro‐industrial residues. Thus the objective of this research was the bio‐production of carotenoids by Sporidiobolus salmonicolor using agro‐industrial substrates (corn steep liquor and sugarcane molasses), pre‐treated with acids (sulphuric and phosphoric). RESULTS: Bio‐production was carried out in an orbital shaker using a 10% (v/v) inoculum, incubation at 25 °C, and agitation at 180 rpm for 120 h in a non‐illuminated environment. The carotenoids were recovered using liquid N₂ combined with dimethylsulphoxide for cell rupture, and an acetone/methanol mixture (7:3 v/v) for extraction. CONCLUSION: The complete second‐order design allowed for optimisation of the carotenoid concentration obtained from industrial substrates pre‐treated with acids (sulphuric and phosphoric), obtaining a total carotenoid content of 541.5 µg L^?1 using 10 g L^?1 sugarcane molasses, 5 g L^?1 corn steep liquor and 5 g L^?1 yeast hydrolysate at 25 °C, with agitation at 180 rpm and an initial pH of 4.0. Copyright © 2008 Society of Chemical Industry     

Evaluation of the conditions of carotenoids production in a synthetic medium by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor

This work studied the cultivation conditions for the production of carotenoids by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor. A Plackett–Burman design was used for the screening of the most important factors, followed by a complete second order design, to maximise the concentration of total carotenoids. The maximum concentration of 3425.9 μg L^?1 of total carotenoids was obtained in a medium containing 80 g L^?1 glucose, 15 g L^?1 peptone and 5 g L^?1 malt extract, with an aeration rate 1.5 vvm, 180 r.p.m., 25 °C and an initial pH of 4.0. Fermentation kinetics showed that the maximum concentration of total carotenoids was reached after 90 h of fermentation. Carotenoid bio‐production was partially associated with cell growth. The specific carotenoid production (Y_P/X) was 238 μg carotenoids/g cells, whereas Y_P/S (substrate to product yield) was 41.3 μg g^?1. The specific growth rate (μ_x) was 0.045 h^?1. The highest cell and total carotenoid productivity were 0.19 g L^?1 h^?1 and 56.9 μg L^?1 h^?1, respectively.     

Assessment of Different Packaging Structures in the Stability of Frozen Fresh Brazilian Toscana Sausage

The aim of this work was to evaluate the effect of different package conditions on the characteristics of Toscana fresh sausage stored for 150?days under freezing. The analyses of lipid oxidation, moisture, pH, acidity, water activity, and counting of psychotrophic microorganisms were carried out along with the storage time for each package (low-density polyethylene with and without vacuum and oxygen permeability of 500?cm³ O₂/m² day atm at 23 ??C; nylon polyester with and without vacuum and permeability of 100?cm³ O₂/m² day atm at 23 ??C; and formal copolymer of ethylene and vinyl alcohol with and without vacuum and oxygen permeability of 5?cm³ O₂/m² day atm at 23 ??C). Results showed that from 60?days of storage, the samples stored using polyethylene without vacuum and nylon 100?cm³ O₂/m² day atm, without vacuum, presented a slight rancidity flavor, statistically different (p?<?0.05) from the other tested ones. After 151?days of storage, a relationship between 2-thiobarbituric acid reactive substances analysis and sensory characteristics could be observed. In this case, the packages without application of vacuum presented higher values in the sensory and oxidative rancidity analyses, configuring flavor of slight to moderate rancidity.     

Evaluation of production and characterization of polygalacturonase by Aspergillus niger ATCC 9642

The aim of our study was to evaluate polygalacturonase (PG) production and characterization by Aspergillus niger ATCC 9642. The maximum PG activity (51.82 U/mL) was obtained using pectin, l-asparagine, and, iron sulphate concentrations of 32 g/L, 2 g/L, 0.06 g/L and 1.0 g/L, respectively; 180 rpm of stirring rate, 25 °C and an initial pH of 4.0. The kinetic study showed that the highest enzyme activity was achieved at 27 h of fermentation. The evaluation of the optimum pH and temperature permitted us to observe that highest PG activities were achieved at 37 °C and pH of 5.5. The enzymatic extract presented higher stability at 55 °C and pH of 5.0. The results showed that at low temperatures the enzyme extract kept the initial activity until 40 days of storage. The experimental design methodology permitted us to optimize the PG activity and an important aspect of this study is the characterization of the PG in terms of optimum temperature and pH using experimental design technique and also, the characterization of enzyme stability at low temperature. Such studies are very scarce in the literature and should be helpful to understand the true potentialities of pectinases in its industrial applications.