Pisacane, Sara (2025) PRODUCTION OF SOLVENTS AND COMMODITY CHEMICALS VIA SYNGAS FERMENTATION. [Tesi di dottorato]

Documento PDF Pisacane_Sara_38.pdf Visibile a [TBR] Amministratori dell'archivio Download (5MB) | Richiedi una copia

Abstract

The increasing global energy demand and the environmental concerns associated with fossil fuel use have intensified the search for sustainable biotechnological solutions for the production of energy vectors, chemicals, and food/feeds. Syngas, a mixture of CO, CO₂, and H₂ derived from waste streams, offers a promising feedstock for microbial fermentation, enabling the biological valorization of carbon-rich residues within a circular bioeconomy framework. Continuous stirred-tank reactors (CSTRs) have been used to investigate the metabolic performance of Clostridium carboxidivorans, an acetogenic bacterium capable of converting CO and syngas into short-chain products such as acetate, ethanol, butanol, and hexanol. Alongside the experimental investigations, a dynamic kinetic model was developed to describe the growth and product formation under different operating conditions. The influence of key variables—including pH, dilution rate, and gas composition—was systematically assessed and interpreted through the model, providing insights into process behavior and optimization strategies. To enhance the value of primary fermentation products, the chain elongation process was studied using Clostridium kluyveri, which catalyzes the conversion of acetate and ethanol into medium-chain fatty acids (MCFAs). Both batch and continuous experiments were performed, and a complementary kinetic model was established to predict metabolite dynamics and identify optimal operating conditions. Finally, a novel co-culture approach was explored in collaboration with Wageningen University & Research. A synthetic consortium of Geobacter sulfurreducens and C. kluyveri was designed, where G. sulfurreducens oxidized CO with fumarate as electron acceptor, generating succinate as an intermediate substrate for C. kluyveri. The latter uses succinate and ethanol to drive chain elongation and produce MCFAs. This proof-of-concept study demonstrated the feasibility of integrating CO valorization with chain elongation, highlighting the potential of co-cultivation strategies to advance sustainable bioprocesses for biofuel and biochemical production from non-food and waste resources.

Downloads

Actions (login required)

Modifica documento