Methionine affects the freeze‐drying resistance of Lactiplantibacillus plantarum LIP‐1 by improving its antioxidant capacity

Abstract BACKGROUND Lactic acid bacteria is an essential industrial strain, and improving its freeze‐drying survival rate is the key challenge to ensuring the activity and stability of bacterial powder. Although medium optimization has been shown to strengthen strain freeze‐drying tolerance, the mechanism by which amino acids repair freeze‐drying damage in lactic acid bacteria remains unclear. This study investigated the effects of methionine on the freeze‐drying survival rate of Lactiplantibacillus plantarum LIP‐1 and explored the underlying protective mechanisms. Results The study demonstrates that supplementing the medium with 0.06 g/L methionine significantly improved the freeze‐drying survival rate of Lactiplantibacillus plantarum LIP‐1 ( P < 0.05). Further analysis revealed that the strain significantly reduced intracellular reactive oxygen species levels through metabolizing methionine ( P < 0.05), decreased the oxidation degree of unsaturated fatty acids in the cell membrane, and reduced cell membrane damage, thereby strengthening the freeze‐drying resistance of the strain. Conclusion Methionine can enhance the freeze‐drying resistance of Lactiplantibacillus plantarum LIP‐1 by enhancing antioxidant capacity and maintaining the stability of the subcellular structure. This study provides a specific reference value for improving the freeze‐drying survival rate of lactic acid bacteria by modifying the medium conditions. © 2025 Society of Chemical Industry.