Comparative molecular profiling of Lactiplantibacillus plantarum-derived single-cell protein produced from food-derived substrates.

BACKGROUND: Single-cell protein (SCP) derived from microbial systems is gaining attention as a sustainable alternative protein source for food applications. However, the influence of food-derived substrates on protein accumulation and molecular characteristics in Lactiplantibacillus plantarum-derived SCP remains poorly understood. Therefore, this study investigated substrate-dependent molecular profiling of SCP produced using fermented rice water and paneer extract through biomass evaluation, protein quantification, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, and liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS)-based molecular fingerprinting. RESULTS: Paneer extract supported the highest viable cell count (2.43 × 106 CFU mL-1) and highest mean wet biomass yield (2.82 g L-1), whereas fermented rice water resulted in the highest total protein concentration (1.000 g L-1) and protein productivity (0.0417 g L-1 h-1). SDS-PAGE analysis revealed enhanced electrophoretic band intensity within the 25-75 kDa range in rice-derived SCP samples. Comparative LC-ESI-MS/MS profiling demonstrated conserved chromatographic architectures together with substrate-responsive variations in retention-region distribution and molecular heterogeneity, particularly within intermediate- and late-eluting regions. Statistical analysis confirmed significant differences among treatments (P < 0.05). CONCLUSION: The divergence between wet biomass production and total protein accumulation indicates that substrate composition differentially regulates metabolic allocation in L. plantarum-derived SCP systems. Fermented rice water promoted greater total protein enrichment despite lower biomass formation, suggesting substrate-specific biochemical modulation. LC-MS-based molecular fingerprinting further demonstrated that food-derived substrates influence molecular distribution behavior and compositional heterogeneity within SCP biomass. © 2026 Society of Chemical Industry.