Development of fermentation strategies to enable the production of butanol from energy-cane products

• Grant number: 23/01219-8
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2024
• End date: February 28, 2027
• Field of knowledge: Engineering - Chemical Engineering - Chemical Process Industries
• Principal Investigator: Adriano Pinto Mariano
• Grantee: Bruno Xavier Ferreira
• Host Institution: Faculdade de Engenharia Química (FEQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Butanol is an industrially important chemical and emerging alternative fuel, and its production by energy-cane ethanol mills may mitigate the financial risks that these mills face because energy-cane juice is poor in sucrose content and thus not suitable for the production of table sugar. This Ph.D. research proposes that energy-cane ethanol mills should be designed to process biomass-derived carbohydrates (cellulose and hemicellulose) separately so that the hemicellulose-derived xylose, instead of being used to produce ethanol, could be converted to butanol by naturally xylose-fermenting microorganisms such as solventogenic Clostridium species. The separate fermentation strategy, however, is challenged by the fact that several microbial inhibitory compounds are produced during thermal and acid-assisted pretreatment techniques needed to produce hemicellulose hydrolysates. As such, this research aims to develop fermentation strategies to enable the conversion of hemicellulose hydrolysate from energy cane into butanol and coproducts without the need for costly upstream detoxification methods. The core of the strategies consists of initiating the cultivation of butanol-producing microorganisms in energy-cane juice, allowing for the buildup of cells, and then concentrated non-detoxified hemicellulose hydrolysate is fed intermittently so that the microorganisms are not exposed to the full-loading of inhibitors at once. Due to an expected need for excessive dilution of the hemicellulose hydrolysate in the juice, which would decrease the fraction of lignocellulose-derived butanol in the fermentation product, this research will study whether this issue can be mitigated by in-situ detoxification and light stimulation. Finally, this research will investigate whether the co-culturing of two Clostridium species, one butanol-producer and another butyric acid-producer, and a butanol-producing Clostridium specie and the ethanol-producer Saccharomyces cerevisiae may enhance the butanol yield in the proposed fermentation strategies.