Lactiplantibacillus plantarum peptides and probiotics from peanut butter enhance antimicrobial activity and gut microbiota modulation

Abstract

Background Fermented plant matrices with probiotics show antimicrobial and gut health potential. Still, the quantitative links between peanut fermentation, peptide–probiotic synergy, digestive survival, and microbiota modulation remain unclear. Objective We optimized bioactive peptide production from reduced-fat (33%) and full-fat (50%) peanut butter fermented with Lactiplantibacillus plantarum ATCC 14917 for 0–72 h using a full factorial design. Methods The < 3 kDa peptide fraction was combined with Lactobacillus acidophilus ATCC 4356 and Bifidobacterium bifidum ATCC 29521 at sub-inhibitory levels. Antimicrobial activity against Salmonella enterica serovar Typhimurium, Listeria monocytogenes, and Clostridioides difficile was tested by agar diffusion, MIC, MBC, and checkerboard assays. Gastrointestinal stability followed the INFOGEST protocol, and colonic fermentation used fecal inoculum from three healthy donors to track microbiota and short-chain fatty acids (SCFAs). Results At 72 h of fermentation, reduced-fat matrix reached 61.3% hydrolysis and 9.45 log10 CFU/mL, which was 16% above full-fat. The combination treatment (5 mg/mL peptides plus 4.5 × 104 CFU/mL probiotics) lowered L. monocytogenes MIC by 75% to 1.25 mg/mL, with a fractional inhibitory concentration (FIC) index of 0.50 indicating synergy. During simulated gastrointestinal digestion, the combination maintained 87.1% bacterial survival and 85.8% peptide retention. In colonic fermentation, the combination raised Bifidobacterium to 8.93 log10 CFU/mL and Lactiplantibacillus to 8.71 log10 CFU/mL, dropped Clostridium to 3.31 log10 CFU/mL, increased the B/C ratio to 2.70, and boosted total SCFAs by 467% to 46.5 μmol/mL. Conclusion L. plantarum fermentation of reduced-fat peanut generates peptides that, with probiotics, give synergistic antimicrobial effects, better GI stability, and microbiota shifts toward higher SCFAs. This supports peanut-based synbiotic foods.