Advances in the biological production of butyric acid.

Butyric acid, a short-chain organic acid, is extensively used in the chemical, food, and pharmaceutical industries. Given the constraints in raw materials for traditional chemical synthesis and the rising consumer preference for natural products, microbial fermentation has emerged as a promising and sustainable alternative for butyric acid manufacture. This review provides a detailed elaboration of four biosynthetic pathways for microbial butyric acid production. It summarizes recent advances in butyric acid producers, encompassing both natural producers like Clostridium and emerging producers such as Escherichia coli. Their fermentation performance is systematically compared based on key metrics, including yield, tolerance, substrate utilization range, and process maturity. Butyric acid production was improved through targeted metabolic engineering and optimized fermentation processes, working in concert to enhance overall biosynthesis efficiency. Finally, it concludes with a summary and a perspective on future research priorities, which are anticipated to focus on systems metabolic engineering and integrated bioprocess development to enhance economic feasibility.