Single cell protein (SCP): Microbial bioconversion strategies for sustainable protein security and circular bioeconomy

Abstract

The growing global demand for sustainable protein sources has contributed to an increased interest in microbial single cell protein (SCP) as an alternative to traditional plant and animal-based proteins. The term SCP refers to protein-rich biomass obtained from non-pathogenic microorganisms such as bacteria, yeast, filamentous fungus, and microalgae. Because of their rapid growth rates, excellent substrate conversion efficiency, and resistance to climatic and seasonal changes, these microorganisms represent ideal biological platforms for protein production. The physiological and metabolic characteristics influencing biomass yield, protein composition, and nucleic acid content are highlighted in this paper, which provides an overview of the advancements in microbial strain diversity. The ability of diverse microorganisms to use renewable and low-cost substrates such as agro-industrial residues, lignocellulosic biomass, waste effluents, methanol, and gaseous carbon sources is highlighted, allowing for sustainable single-cell protein (SCP) production via integrated bioconversion processes. Recent improvements in fermentation technologies, such as batch, fed-batch, and continuous cultivation systems, are evaluated in terms of downstream processing, substrate management, oxygen transfer efficiency, and overall process optimization. Important factors such high nucleic acid concentration, digestibility of cell walls, cost of harvesting, and safety concerns are also evaluated. Important factors are also investigated, including increased nucleic acid levels, the digestibility of microbial cell walls, harvesting expenses, and safety concerns. In order to increase nutritional quality and economic viability, options for nucleic acid reduction, cell disruption, strain improvement, and genetic manipulation are addressed. Overall, microbial SCP synthesis is a biologically sound and industrially scalable strategy for addressing the global protein deficit as well as contributing to the principles of waste valorization and circular bioeconomy. Continued advancements in microbial physiology, metabolic engineering, and bioprocess optimization are necessary to improve cost-effectiveness, product safety, and large-scale implementation.