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Open AccessArticle

Xylose-Enriched Ethanol Fermentation Stillage from Sweet Sorghum for Xylitol and Astaxanthin Production

Sustainable Biofuels and Co-Products Research Unit, Eastern Regional Research Center, USDA, ARS, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
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Fermentation 2019, 5(4), 84; https://doi.org/10.3390/fermentation5040084
Received: 26 August 2019 / Revised: 13 September 2019 / Accepted: 17 September 2019 / Published: 23 September 2019
(This article belongs to the Special Issue Ethanol and Value-Added Co-Products 2.0)
Developing integrated biorefineries requires the generation of high-value co-products produced alongside cellulosic ethanol. Most industrial yeast strains produce ethanol at high titers, but the small profit margins for generating ethanol require that additional high-value chemicals be generated to improve revenue. The aim of this research was to boost xylose utilization and conversion to high-value co-products that can be generated in an integrated biorefinery. Pretreated sweet sorghum bagasse (SSB) was hydrolyzed in sweet sorghum juice (SSJ) followed by ethanol fermentation. Ethanol was removed from the fermentation broth by evaporation to generate a stillage media enriched in xylose. Candida mogii NRRL Y-17032 could easily grow in non-detoxified stillage media, but a high xylitol yield of 0.55 g xylitol/g xylose consumed was achieved after recovered cells were resuspended in synthetic media containing supplemented xylose. Phaffia rhodozyma ATCC 74219 could be cultivated in non-detoxified stillage media, but astaxanthin generation was increased 4-fold (from 17.5 to 71.7 mg/L) in detoxified media. Future processing strategies to boost product output should focus on a two-step process where the stillage media is used as the growth stage, and a synthetic media for the production stage utilizing xylose generated from SSB through selective hemicellulase enzymes. View Full-Text
Keywords: sweet sorghum; xylose; Candida mogii; Phaffia rhodozyma; xylitol; astaxanthin sweet sorghum; xylose; Candida mogii; Phaffia rhodozyma; xylitol; astaxanthin
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MDPI and ACS Style

Stoklosa, R.J.; Nghiem, N.P.; Latona, R.J. Xylose-Enriched Ethanol Fermentation Stillage from Sweet Sorghum for Xylitol and Astaxanthin Production. Fermentation 2019, 5, 84.

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