Dataset Information

Xylose fermentation to ethanol by new Galactomyces geotrichum and Candida akabanensis strains.

ABSTRACT: The conversion of pentoses into ethanol remains a challenge and could increase the supply of second-generation biofuels. This study sought to isolate naturally occurring yeasts from plant biomass and determine their capabilities for transforming xylose into ethanol. Three yeast strains with the ability to ferment xylose were isolated from pepper, tomato and sugarcane bagasse. The strains selected were characterized by morphological and auxanographic assays, and they were identified by homology analysis of 5.8 S and 26 S ribosomal RNA gene sequences. The identities of two lineages of microrganism were associated with Galactomyces geotrichum, and the other was associated with Candida akabanensis. Fermentative processes were conducted with liquid media containing only xylose as the carbon source. YP/S values for the production of ethanol ranging between 0.29 and 0.35 g g-1 were observed under non-optimized conditions.

SUBMITTER: Valinhas RV

PROVIDER: S-EPMC5926554 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Publications

Xylose fermentation to ethanol by new <i>Galactomyces geotrichum</i> and <i>Candida akabanensis</i> strains.

Valinhas Raquel V RV Pantoja Lílian A LA Maia Ana Carolina F ACF Miguel Maria Gabriela C P MGCP Vanzela Ana Paula F C APFC Nelson David L DL Santos Alexandre S AS

PeerJ 20180427

The conversion of pentoses into ethanol remains a challenge and could increase the supply of second-generation biofuels. This study sought to isolate naturally occurring yeasts from plant biomass and determine their capabilities for transforming xylose into ethanol. Three yeast strains with the ability to ferment xylose were isolated from pepper, tomato and sugarcane bagasse. The strains selected were characterized by morphological and auxanographic assays, and they were identified by homology a ...[more]

PMID: 29719736

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Project description:BACKGROUND: There has been much research on the bioconversion of xylose found in lignocellulosic biomass to ethanol by genetically engineered Saccharomyces cerevisiae. However, the rate of ethanol production from xylose in these xylose-utilizing yeast strains is quite low compared to their glucose fermentation. In this study, two diploid xylose-utilizing S. cerevisiae strains, the industrial strain MA-R4 and the laboratory strain MA-B4, were employed to investigate the differences between anaerobic fermentation of xylose and glucose, and general differences between recombinant yeast strains, through genome-wide transcription analysis. RESULTS: In MA-R4, many genes related to ergosterol biosynthesis were expressed more highly with glucose than with xylose. Additionally, these ergosterol-related genes had higher transcript levels in MA-R4 than in MA-B4 during glucose fermentation. During xylose fermentation, several genes related to central metabolic pathways that typically increase during growth on non-fermentable carbon sources were expressed at higher levels in both strains. Xylose did not fully repress the genes encoding enzymes of the tricarboxylic acid and respiratory pathways, even under anaerobic conditions. In addition, several genes involved in spore wall metabolism and the uptake of ammonium, which are closely related to the starvation response, and many stress-responsive genes mediated by Msn2/4p, as well as trehalose synthase genes, increased in expression when fermenting with xylose, irrespective of the yeast strain. We further observed that transcript levels of genes involved in xylose metabolism, membrane transport functions, and ATP synthesis were higher in MA-R4 than in MA-B4 when strains were fermented with glucose or xylose. CONCLUSIONS: Our transcriptomic approach revealed the molecular events underlying the response to xylose or glucose and differences between MA-R4 and MA-B4. Xylose-utilizing S. cerevisiae strains may recognize xylose as a non-fermentable carbon source, which induces a starvation response and adaptation to oxidative stress, resulting in the increased expression of stress-response genes.

Dataset Information

Xylose fermentation to ethanol by new Galactomyces geotrichum and Candida akabanensis strains.

Publications

Xylose fermentation to ethanol by new <i>Galactomyces geotrichum</i> and <i>Candida akabanensis</i> strains.

Similar Datasets

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