Polyols: a study of the simultaneous biological production of xylitol and arabitol from agroindustrial waste

Author(s)

Gabriel Cicalese Bevilaqua

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2023-03-06

Examining board members

Marcus Bruno Soares Forte; Ruann Janser Soares de Castro; Eliana Setsuko Kamimura

• Advisor: Francisco Maugeri Filho; Marcus Bruno Soares Forte

Abstract

Xylitol and arabitol are stereoisomeric polyalcohols that have similar properties and applications and arouse market interest. Even though the chemical route is currently more used in the production of these compounds, production through fermentation processes uses mild conditions and is less environmentally harmful. Despite this, the biotechnological route presents difficulties such as the low yield and the economic viability of the process. In this context, production optimization studies stand out as a way to make the process more profitable, using hemicellulosic hydrolysates of lignocellulosic biomass as carbon sources, for example, and opportunities not yet explored can be developed, such as the simultaneous use of the two polyalcohols, which would dispense with the process of separating them. This project sought to optimize the biological coproduction of xylitol and arabitol from the hemicellulosic hydrolysate of sugarcane bagasse and alternative nitrogen sources. For this, the possibility of using Candida tropicalis for the conversion of pentoses into polyalcohols and their respective adaptation to the detoxified hemicellulosic hydrolysate of sugarcane bagasse was verified. Then, it was defined that the yeast hydrolysate was the most promising source to be added to the medium and allow a greater production of the target compounds. From experimental design strategies (DOE), it was possible to define a composition and favorable conditions for the fermentation process with the insertion of corn steep water as a source of additional nitrogen to the process, with the most promising condition for co-production being composed of hemicellulosic hydrolysate diluted to 75 g/L of initial xylose, initial pH of 6.5 and addition of 2.2 g/L of nitrogen, being composed 80% by yeast hydrolysate and 20% by corn steep liquor. From the scale-up in bioreactors it was possible to obtain concentrations of xylitol (52.1 g/L) and arabitol (4.2 g/L) which are 65 and 3.7 higher, respectively, in relation to similar processes of co -production found in the literature, showing productivities and yields of 0.24 g/L.h and 0.74 g/g for xylitol and 0.02 g/L.h and 0.43 g/g for arabitol. These results show the biotechnological potential for simultaneously obtaining these two sugar alcohols from the fermentation of sugarcane bagasse hemicellulosic hydrolysate by C. tropicalis (AU)

• FAPESP's process: 21/05508-9 - Optimization study of hemicellulosic hydrolyzate fermentation for the co-production of xylitol and arabitol by Candida tropicalis
• Grantee: Gabriel Cicalese Bevilaqua
• Support Opportunities: Scholarships in Brazil - Master