Advances in Bioprocess Engineering for Sustainable Biotechnology: A Critical Review
Bioprocess engineering sits at the interface of biology and chemical engineering and has become a central pillar of the transition towards a low-carbon, circular economy. Over the past decade, advances in strain design, bioreactor engineering, biocatalysis, feedstock diversification, downstream processing and digitalisation have collectively reshaped how biological systems are engineered for industrial production. This review synthesises recent literature on these interconnected domains, with particular emphasis on sustainability outcomes such as reduced water and energy intensity, greenhouse gas mitigation, waste valorisation and circularity of biobased materials. Upstream innovations, including CRISPR-based genome editing, dynamic metabolic control and membrane engineering, have improved the robustness and productivity of microbial cell factories. In parallel, bioreactor engineering has progressed through single-use technologies, continuous and intensified processing and improved oxygen transfer strategies, although trade-offs between operational flexibility and environmental burden remain contested. Biocatalysis has matured through advances in enzyme immobilisation, enabling greener, more selective and reusable industrial catalysts. Feedstock diversification towards lignocellulosic residues, gaseous one-carbon substrates and microalgal biomass has expanded the substrate base available to fermentation industries, while precision fermentation and polyhydroxyalkanoate biosynthesis illustrate the growing convergence between food, materials and waste-valorisation sectors. Digital tools, including process analytical technology, machine learning and digital twins, are increasingly embedded within what is termed Bioprocessing 4.0, offering real-time control and predictive optimisation. This review draws on close to thirty peer-reviewed sources published within the last decade to critically appraise these developments, identify persistent technical and economic bottlenecks and outline priorities for future research. The evidence indicates that sustainable bioprocess engineering is no longer a peripheral consideration but a defining criterion against which new bioprocesses must be evaluated.