RESUMEN
Patulin (PAT) is a mycotoxin produced by Penicillium species, which often contaminates fruit and fruit-derived products, posing a threat to human health and food safety. This work aims to investigate the detoxification of PAT by Kluyveromyces marxianus YG-4 (K. marxianus YG-4) and its application in apple juice. The results revealed that the detoxification effect of K. marxianus YG-4 on PAT includes adsorption and degradation. The adsorption binding sites were polysaccharides, proteins, and some lipids on the cell wall of K. marxianus YG-4, and the adsorption groups were hydroxyl groups, amino acid side chains, carboxyl groups, and ester groups, which were combined through strong forces (ion interactions, electrostatic interactions, and hydrogen bonding) and not easily eluted. The degradation active substance was an intracellular enzyme, and the degradation product was desoxypatulinic acid (DPA) without cytotoxicity. K. marxianus YG-4 can also effectively adsorb and degrade PAT in apple juice. The contents of organic acids and polyphenols significantly increased after detoxification, significantly improving the quality of apple juice. The detoxification ability of K. marxianus YG-4 toward PAT would be a novel approach for the elimination of PAT contamination.
Asunto(s)
Jugos de Frutas y Vegetales , Kluyveromyces , Malus , Patulina , Kluyveromyces/metabolismo , Kluyveromyces/química , Patulina/metabolismo , Patulina/química , Malus/química , Malus/metabolismo , Jugos de Frutas y Vegetales/análisis , Contaminación de Alimentos/análisis , AdsorciónRESUMEN
ABSTRACT The present study evaluated the purification of inulinase by changing the ionic strength of the medium by addition of NaCl and CaCl2 followed by precipitation with n-propyl alcohol or iso-propyl alcohol. The effects of the concentration of alcohols and the rate of addition of alcohols in the crude extract on the purification yield and purification factor were evaluated. Precipitation caused an activation of enzyme and allowed purification factors up to 2.4-fold for both alcohols. The purification factor was affected positively by the modification of the ionic strength of the medium to 0.5 mol.L-1 NaCl before precipitation with the alcohol (n-propyl or iso-propyl). A purification factor of 4.8-fold and an enzyme yield of 78.1 % could be achieved by the addition of 0.5 mol.L-1 of NaCl to the crude extract, followed by the precipitation with 50 % (v/v) of n-propyl alcohol, added at a flow rate of 19.9 mL/min.
Asunto(s)
Concentración Osmolar , Precipitación Química , Alcoholes/química , Glicósido Hidrolasas/aislamiento & purificación , Glicósido Hidrolasas/química , Valores de Referencia , Sales (Química)/química , Solventes/química , Kluyveromyces/aislamiento & purificación , Kluyveromyces/química , Cloruro de Calcio/química , Cloruro de Sodio/química , Reproducibilidad de los Resultados , Medios de Cultivo/químicaRESUMEN
Abstract Stress tolerance is a key attribute that must be considered when using yeast cells for industrial applications. High temperature is one factor that can cause stress in yeast. High environmental temperature in particular may exert a natural selection pressure to evolve yeasts into thermotolerant strains. In the present study, three yeasts (Saccharomyces cerevisiae, MC4, and Kluyveromyces marxianus, OFF1 and SLP1) isolated from hot environments were exposed to increased temperatures and were then compared with a laboratory yeast strain. Their resistance to high temperature, oxidative stress, and antioxidant response were evaluated, along with the fatty acid composition of their cell membranes. The SLP1 strain showed a higher specific growth rate, biomass yield, and biomass volumetric productivity while also showing lower duplication time, reactive oxygen species (ROS) production, and lipid peroxidation. In addition, the SLP1 strain demonstrated more catalase activity after temperature was increased, and this strain also showed membranes enriched in saturated fatty acids. It is concluded that the SLP1 yeast strain is a thermotolerant yeast with less oxidative stress and a greater antioxidant response. Therefore, this strain could be used for fermentation at high temperatures.
Asunto(s)
Saccharomyces cerevisiae/fisiología , Estrés Fisiológico , Kluyveromyces/fisiología , Estrés Oxidativo , Antioxidantes/metabolismo , Saccharomyces cerevisiae/crecimiento & desarrollo , Saccharomyces cerevisiae/efectos de la radiación , Saccharomyces cerevisiae/química , Kluyveromyces/crecimiento & desarrollo , Kluyveromyces/efectos de la radiación , Kluyveromyces/química , Peroxidación de Lípido , Catalasa/análisis , Membrana Celular/química , Especies Reactivas de Oxígeno/metabolismo , Biomasa , Ácidos Grasos/análisis , CalorRESUMEN
This work investigated the partitioning of (beta)-galactosidase from "Kluyveromyces fragilis" in aqueous two-phase systems (ATPS) by bioaffinity. PEG 4000 was chemically activated with thresyl chloride, and the biospecific ligand p-aminophenyl 1-thio-(beta)-D-galactopyranoside (APGP) was attached to the activated PEG 4000. A new two-step method for extraction and purification of the enzyme (beta)-galactosidase from "Kluyveromyces fragilis" was developed. In the first step, a system composed of 6(per cent) PEG 4000-APGP and 8(per cent) dextran 505 was used, where (beta)-galactosidase was strongly partitioned to the top phase (K = 2.330). In the second step, a system formed of 13(per cent) Peg-APGP and 9(per cent) phosphate salt was used to revert the value of the partition coefficient of (beta)-galactosidase (K = 2.0E-5) in order to provide the purification and recovery of 39(per cent) of the enzyme in the bottom salt-rich phase
Asunto(s)
Kluyveromyces/enzimología , Kluyveromyces/química , beta-Galactosidasa/análisis , Proteínas/análisis , Proteínas/química , Electroforesis , Cromatografía Liquida/métodosRESUMEN
The milk whey from a mature cheese factory deproteinised by acid thermic coagulation (pH 4.5 and 90 degrees C), provides a good culture media for the production of Kluyveromices fragilis biomass. The optimal experimental conditions for the maximal production of biomass were established by using fermenters with different capacity and design. For lactose concentration of 15 g/l, pH 4.5, 30 degrees C and aireation between 0.25 and 1 VVM, the duplication time was below two hours and 98 per cent of the lactose was consumed. The obtained yield in dried weight was between 36 and 49 per cent (g biomass/g lactose). The biomass (without broken cell) contain 46 per cent protein on dry base and showed an "in vitro" digestibility of 65 per cent. The organic mass decreased 80 per cent after 12 hour of fermentation. This process eliminates a polluting agent and simutaneously, produces a biomass that could have industrial use as a protein complement in feeds.
Asunto(s)
Animales , Kluyveromyces/metabolismo , Biomasa , Leche/microbiología , Kluyveromyces/química , Queso/microbiología , FermentaciónRESUMEN
De la fermentación de suero de leche entera se obtuvo un producto consistente en una mezcla de biomasa de Kluyveromyces fragilis y proteínas coaguladas del suero. El producto tuvo una composición similar a la de productos lavados de que se informa en la literatura, con un alto contenido de proteína cruda y un bajo contenido de cenizas. Asimismo, acusó tambiém un alto contenido de aminoácidos azufrados y de triptofano, los que usualmente son limitantes en al biomasa de levadura. El contenido de lisina fue inexplicablemente más bajo de lo esperado resusltando ser el aminoácido limitante. La calificación química de la protéina fue 91%. Del producto de biomasa com proteínas de suero se obtuvo un concentrado proteínico con un rendimento de 80%. El contenido de proteína del aislado fue de 75% y el contenido de ácidos nucleícos se redujó en 90.8%. Los restos de pared celular también se redujeron considerablemente