The transition toward sustainable production of platform chemicals necessitates the development of bio-based processes capable of utilising renewable and non-food biomass. This PhD research explores the fermentative production of value-added chemicals using acetogenic bacteria, a physiologically diverse group of anaerobes known for their ability to fix CO₂ and convert a broad range of carbon sources via the Wood–Ljungdahl pathway, alongside other carbon fixation routes under investigation. Central to this work is the valorisation of second-generation (2G) feedstocks derived from lignocellulosic biomass, coupled with integrated in situ CO₂ recycling to enhance overall carbon efficiency.

The research integrates fundamental microbial characterisation with process development, ranging from high-throughput screening to fermentations in small-scale bioreactors (up to 7 L). Special attention is given to the challenges posed by 2G substrates, including their chemical complexity, energetic demands, and the presence of inhibitory compounds such as furans and phenolics. By identifying and optimising robust acetogenic strains capable of tolerating and converting these hydrolysates, the work aims to advance carbon-conserving pathways that minimise CO₂ losses and resist metabolic inhibition.

Ultimately, this research contributes to the development of scalable, low-emission microbial platforms that valorise underutilised biomass and align with the principles of a circular and decarbonised bioeconomy.