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Open AccessArticle

Xylitol Production: Identification and Comparison of New Producing Yeasts

1
Laboratory of Genetics and Biotechnology, Embrapa Agroenergy, Brasilia 70770-901, Brazil
2
Graduate Program of Microbial Biology, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia 70910-900, Brazil
3
Graduate Program of Chemical and Biological Technologies, Institute of Chemistry, University of Brasilia, Brasilia 70910-900, Brazil
*
Authors to whom correspondence should be addressed.
Microorganisms 2019, 7(11), 484; https://doi.org/10.3390/microorganisms7110484
Received: 2 September 2019 / Accepted: 14 September 2019 / Published: 23 October 2019
(This article belongs to the Special Issue Non-conventional Yeasts: Genomics and Biotechnology)
Xylitol is a sugar alcohol with five carbons that can be used in the pharmaceutical and food industries. It is industrially produced by chemical route; however, a more economical and environmentally friendly production process is of interest. In this context, this study aimed to select wild yeasts able to produce xylitol and compare their performance in sugarcane bagasse hydrolysate. For this, 960 yeast strains, isolated from soil, wood, and insects have been prospected and selected for the ability to grow on defined medium containing xylose as the sole carbon source. A total of 42 yeasts was selected and their profile of sugar consumption and metabolite production were analyzed in microscale fermentation. The six best xylose-consuming strains were molecularly identified as Meyerozyma spp. The fermentative kinetics comparisons on defined medium and on sugarcane bagasse hydrolysate showed physiological differences among these strains. Production yields vary from YP/S = 0.25 g/g to YP/S = 0.34 g/g in defined medium and from YP/S = 0.41 g/g to YP/S = 0.60 g/g in the hydrolysate. Then, the xylitol production performance of the best xylose-consuming strain obtained in the screening, which was named M. guilliermondii B12, was compared with the previously reported xylitol producing yeasts M. guilliermondii A3, Spathaspora sp. JA1, and Wickerhamomyces anomalus 740 in sugarcane bagasse hydrolysate under oxygen-limited conditions. All the yeasts were able to metabolize xylose, but W. anomalus 740 showed the highest xylitol production yield, reaching a maximum of 0.83 g xylitol/g of xylose in hydrolysate. The screening strategy allowed identification of a new M. guilliermondii strain that efficiently grows in xylose even in hydrolysate with a high content of acetic acid (~6 g/L). In addition, this study reports, for the first time, a high-efficient xylitol producing strain of W. anomalus, which achieved, to the best of our knowledge, one of the highest xylitol production yields in hydrolysate reported in the literature. View Full-Text
Keywords: xylitol; xylose; hydrolysate; fermentation; sugarcane xylitol; xylose; hydrolysate; fermentation; sugarcane
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MDPI and ACS Style

Carneiro, C.V.G.C.; Silva, F.C.P.; Almeida, J.R.M. Xylitol Production: Identification and Comparison of New Producing Yeasts. Microorganisms 2019, 7, 484.

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