Advancing psychrophilic fermentation: strategies for enhancing volatile fatty acid production

Abstract

Volatile fatty acids (VFAs) are valuable bio-based intermediates with applications in biofuels, bioplastics, and other industrial processes. As products of the carboxylate platform, VFAs serve as versatile precursors for various chemicals, contributing to a sustainable bioeconomy. Acidogenic fermentation under mesophilic and thermophilic conditions has been widely studied. However, these systems require significant energy inputs for heating, especially in colder climates. Psychrophilic fermentation offers a sustainable alternative with benefits such as lower energy inputs, enhanced carbon conversion efficiency, and reduced emissions. This review explores the strategies for enhancing VFA production under psychrophilic conditions to unlock the potential of low-temperature fermentation. A comprehensive discussion of the challenges associated with conventional fermentation systems highlights the unique advantages of psychrophilic fermentation. Key microbial adaptations and metabolic pathways in low-temperature environments are discussed, along with the influence of temperature on reaction kinetics and substrate utilization. Strategies for improving VFA yields include optimizing operational parameters, designing low-temperature reactors, applying pretreatment methods for substrates, and leveraging bioaugmentation with psychrophilic strains. Co-digestion of substrates and integration of bioelectrochemical systems are also evaluated for their potential to enhance acidogenesis. The review concludes with perspectives on microbial engineering, hybrid systems, and the economic feasibility of cold-adapted fermentation technologies, emphasizing their respective roles in advancing the carboxylate platform and sustainable bio-based production in cold regions.