Comparative of Lignocellulosic Ethanol Production by Kluyveromyces marxianus and Saccharomyces cerevisiae

The world faces a progressive depletion of its energy resources, mainly fossil fuels based on non-renewable resources. At the same time, the consumption of energy grows at high rates, and the intensive use of fossil fuels has led to an increase in the generation of gaseous pollutants released into the atmosphere, which has caused changes in the global climate. The lignocellulosic bioethanol is considered as a promising alternative for use as fuel ethanol. However, one of the main problems in producing ethanol is toxic compounds generated during hydrolysis of lignocellulosic wastes; these compounds cause a longer lag phase and irreversible cell damage to the microorganisms used in the fermentation step. These conditions of fermentation affect the productivity and the economic feasibility of the lignocellulosic ethanol production process. In this context, many efforts had been carried out to improve the capacity of volumetric ethanol productivity of the yeast. The yeast Saccharomyces cerevisiae is commonly employed in industrial ethanol production. However non-Saccharomyces yeast as Kluyveromyces marxianus can produce alcohols at similar or higher levels than S. cerevisiae and on inhibitory conditions

Fermentative capacity of Saccharomyces and non-Saccharomyces in agave juice and semi-synthetic medium

Various consortia of yeasts and bacteria involved in the natural fermentation process of tequila have been identified, particularly non-Saccharomyces yeasts. This study evaluates the fermentative capacity of two non-Saccharomyces yeasts (isolated from traditional mezcal fermentation): Kluyveromyces marxianus (DU3) and Pichia kluyveri (GRO3), and assesses their production of volatile compounds. The values found are compared with those of the same attributes of a Saccharomyces cerevisiae (AR5) isolated from tequila fermentation. The fermentations were performed in two different media, agave juice (JA) and a semi-synthetic medium (M11). The study also compared free and immobilized yeast fermentations in the JA medium in order to evaluate the potential benefits of immobilization on the yeast behaviour. This study demonstrated the potential of non-Saccharomyces yeasts, which fermented the agave juice in the same manner as S. cerevisiae but with higher ester production. Furthermore, K. marxianus produced more higher alcohols than S. cerevisiae. This could lead to tequila with different aroma profiles. Results were different in the synthetic medium, thus showing sensitivity to the composition of the medium. No significant differences between yeast fermentations with free and immobilized cells were detected, except for ethanol yield

Caractérisation de la production et optimisation du processus d'extraction des colorants de la plante de Anil (Indigofera suffruticosa Mill)

Ce travail démontre que l'étape la plus appropriée pour réaliser la récolte de la plante Anil (Indigofea suffruticosa Mill) est environ 5 mois après le semis, à la fin de l'étape de croissance de la plante, car les rendements maxima de Poudre de Colorant Bleu (PCB) et indigo sont obtenus dans cette étape. Les meilleures conditions d'extraction obtenues sur des échantillons de feuille d'anil sèches sont les suivantes : relation matière première/solvant de 1:20 jusqu'à 1:6,5 ; temps d'extraction entre 6 et 8 heures ; température entre 25C et 35C ; pH du solvant 7 pour l'extraction de l'indigo et pH 12 pour extraire l'indigo et indirubine ; temps d'aération compris entre 10 et 30 mn, pH 8 pour l'aération. L'effet principal de l'application des ultrasons pendant l'extraction est la réduction du temps de 6 à 2 heures. Les rendements maxima obtenus sont de 1,79 g de PCB/100 g de feuilles sèches et 3 mg d'indigo/g de feuilles sèches à pH7 et 1,6 mg d'indirubine/g de feuilles sèches à pH 12.TOULOUSE-ENSIACET (315552325) / SudocSudocFranceF

Purification and substrate specificities of a fructanase from Kluyveromyces marxianus isolated from the fermentation process of Mezcal

International audienceA fructanase, produced by a Kluyveromyces marxianus strain isolated during the fermentation step of the elaboration process of "Mezcal de Guerrero" was purified and biochemically characterized. The active protein was a glycosylated dimer with a molecular weight of approximately 250 kDa. The specific enzymatic activity of the protein was determined for different substrates: sucrose, inulin, Agave tequilana fructan, levan and Actilight (R) and compared with the activity of Fructozyme (R). The hydrolysis profile of the different substrates analyzed by HPAEC-PAD showed that the enzyme has different affinities over the substrates tested with a sucrose/inulin enzymatic activity ratio (S/I) of 125. For the hydrolysis of Agave tequilana fructans, the enzyme also showed a higher enzymatic activity and specificity than Fructozyme, which is important for its potential application in the tequila industry. (C) 2010 Elsevier Ltd. All rights reserved

Fructanase and fructosyltransferase activity of non-Saccharomyces yeasts isolated from fermenting musts of Mezcal

Fructanase and fructosyltransferase are interesting for the tequila process and prebiotics production (functional food industry). In this study, one hundred thirty non-Saccharomyces yeasts isolated from "Mezcal de Oaxaca" were screened for fructanase and fructosyltransferase activity. On solid medium, fifty isolates grew on Agave requilana fructans (ATF), inulin or levan. In liquid media, inulin and ATF induced fructanase activities of between 0.02 and 0.27 U/ml depending of yeast isolate. High fructanase activity on sucrose was observed for Kluyveromyces marxianus and Torulaspora delbrueckii, while the highest fructanase activity on inulin and ATF was observed for Issatchenkia orientalis, Cryptococcus albidus, and Candida apicola. Zygosaccharomyces bisporus and Candida boidinii had a high hydrolytic activity on levan. Sixteen yeasts belonging to K. marxianus, T. delbrueckii and C. apicola species were positive for fructosyltransferase activity. Mezcal microbiota proved to showed to be a source for new fructanase and fructosyltransferases with potential application in the tequila and food industry. (C) 2012 Elsevier Ltd. All rights reserved

Efecto del tiempo de cosecha sobre la producción de colorantes en Indigofera suffruticosa mill

El desconocimiento de los factores que afectan la producción y la extracción de índigo en cultivos de añil (Indigofera suffruticosa Mill) ha limitado su explotación comercial. El objetivo de este trabajo fue caracterizar el crecimiento vegetal y la producción de colorante azul en esta especie y determinar el tiempo de cosecha que permita obtener los mejores rendimientos. Para ello se establecieron cultivos de añil en el Estado de Veracruz, México, y se evaluó su desarrollo en talla y peso, y la producción de colorante azul en polvo y de índigo por HPTLC-densitometría. Los cultivos de añil crecieron exponencialmente a partir de 45 d después de la siembra (dds). Al principio se observó desarrollo en altura y posteriormente desarrollo foliar. Las concentraciones más altas de colorante azul en la hoja de añil se presentaron entre 136 a 170. La acumulación de índigo en las hojas se mantuvo cercana a 1g 100 g-----1 en base seca desde 118 hasta 164 dds. En las condiciones de la región de estudio se estableció que los rendimientos por hectárea más altos de colorante azul en polvo e índigo se obtienen a los 150 dds

Galactooligosaccharide Production from Pantoea anthophila Strains Isolated from “Tejuino”, a Mexican Traditional Fermented Beverage

Two Pantoea anthophila bacterial strains were isolated from “tejuino”, a traditional Mexican beverage, and studied as β-galactosidase producers for galactooligosaccharides synthesis. Using 400 g/L of lactose, 50 °C, and 15 U/mL of β-galactosidase activity with ethanol-permeabilized cells, the maximum galactooligosaccharides (GOS) yield determined by High performance anion exchange chromatography with pulse amperometric detection (HPAEC-PAD) was 136 g/L (34% w/w of total sugars) at 96% of lactose conversion for Bac 55.2 and 145 g/L (36% w/w of total sugars) at 94% of lactose conversion for Bac 69.1. The main synthesized products were the disaccharides allolactose [Gal-β(1 → 6)-Glc] and 6-galactobiose [Gal-β(1 → 6)-Gal], as well as the trisaccharides 3′-galactosyl-lactose [Gal-β(1 → 3)-Gal-β(1 → 4)-Glc], 6-galactotriose [Gal-β(1 → 6)-Gal-β(1 → 6)-Gal], 3′-galactosyl-allolactose [Gal-β(1 → 3)-Gal-β(1 → 6)-Glc], and 6′-galactosyl-lactose [Gal-β(1 → 6)-Gal-β(1 → 4)-Glc]. The β-galactosidases present in both strains showed a high transgalactosylation activity and formed principally β(1 → 3) and β(1 → 6) linkages. Considering the stability and bifidogenic properties of GOS containing such types of bonds, P. anthophila strains Bac 55.2 and Bac 69.1 possess a high potential as novel biocatalysts for prebiotic industrial production.This research was supported by the CONACYT project CB-2012-01/000000000181766, and by the Spanish Ministry of Economy and Competitiveness (projects BIO2013-48779-C4-1/3/4 and BIO2016-76601-C3-1-R/2-R/3-R).Peer reviewe

PCR-RFLP de la región ITS-5.8S como herramienta de identificación de levaduras: ventajas y desventajas

Las levaduras juegan un papel muy importante en los procesos de fermentación de bebidas y alimentos, por loque es necesario identificarlas. A finales de los años 90 se propuso la técnica de análisis del polimorfismo en la longitud delos fragmentos de restricción (RFLP) de las regiones ITS-5.8S como una herramienta rápida y confiable para identificarlas.En este trabajo se analizaron 104 cepas de Saccharomyces cerevisiae de la colección de CIATEJ. Además se analizaron lospatrones de bandas publicados hasta el momento para levaduras, lo que nos permitió establecer el parámetro de error de dichatécnica. A partir de este análisis se comprobó que esta técnica es rápida y confiable en la gran mayoría de los casos, sinembargo para algunas especies de levaduras existen ambigüedades en los patrones publicados o no permite diferenciarespecies cercanas