MR-10 peptide from Cordyceps militaris enhances thermotolerance in Lacticaseibacillus paracasei R21 by preserving membrane integrity and promoting biofilm formation.

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Citation abstract

Protein hydrolysates derived from the mycelium of Cordyceps militaris (C. militaris) have shown potential as thermoprotective agents for lactobacilli. To identify the peptides responsible for this effect, albumin and glutenin were separately extracted from C. militaris and hydrolyzed. Results showed that glutenin peptides in the 5-10 kDa range provided optimal protection for Lacticaseibacillus paracasei R21 (L. paracasei R21) during exposure to 65°C for 20 min. A 1 % concentration of these peptides increased viable L. paracasei R21 counts by 2.05 log CFU/mL compared to unsupplemented conditions. Among the five peptides identified by LC-MS/MS, MR-10 (MAVNLVPFPR) exhibited the strongest thermoprotective effect. Adding 0.5 % MR-10 during heating increased cell survival by 0.89 log CFU/mL. Structural analysis of L. paracasei R21 cells exposed to 65°C revealed progressive damage to the membrane, cell wall, and DNA, with membrane damage identified as the main cause of cell death. MR-10 significantly improved cell survival by preserving membrane integrity and morphology, as observed via inverted fluorescence and scanning electron microscopy. Multi-omics analyses revealed that MR-10 participates in peptide transport via ABC transporters, promotes biofilm formation, and boosts fatty acid synthesis. Collectively, these processes reinforce membrane stability and protect cells from heat stress.