Meta-analysis of fruit waste-derived single-cell protein for programmable nutrition via synthetic biology in sustainable food systems

Escalating global protein insecurity, combined with the environmental and economic limitations of conventional plant and animal protein systems, underscores the need for sustainable alternatives. Fruit processing residues, generated at >500 million tons annually worldwide, represent underutilized, carbon-rich bio-resources with potential for microbial protein production. In this PRISMA-compliant meta-analysis, peer-reviewed studies on fruit-derived single-cell protein (SCP) were systematically evaluated across substrate types and microbial platforms. Meta-analysis revealed mean biomass yields of 0.24-37.40 g/L substrate and protein contents ranging from 20.58 to 54.74% (dry weight). Evidence from engineered strains suggests possible improvements in essential amino acid composition, particularly lysine and methionine, although direct validation on fruit-waste substrates remains limited. Synthetic biology interventions may enhance nutrient enrichment and digestibility, yet human clinical or in vivo data are currently lacking. Life-cycle analyses indicate potential reductions in greenhouse gas emissions and land use relative to animal proteins, although energy-intensive pretreatment and substrate heterogeneity may influence these outcomes. Overall, fruit-waste-derived SCP presents a promising avenue for circular bio-economy strategies, offering a framework for programmable nutrition systems that integrate synthetic biology, precision fermentation, and regional waste valorization, while acknowledging the current experimental and translational limitations.