Effects of exogenous amino acids on the freeze-drying survival rate of Lactiplantibacillus plantarum LIP-1

How to improve the freeze-drying survival rate of Lactic acid bacteria (LAB) by increasing its resistance is a problem that is worth paying attention to. We evaluated the effect of exogenous amino acids on freeze-drying resistance of strain using Lactiplantibacillus plantarum LIP-1 as model probiotics. We found that the survival rate of L. plantarum LIP-1 after freeze-dried could be significantly enhanced by adding 0.04 g/L glycine to medium (p < 0.05), compare with other amino acids. Mechanistic studies showed that the content of peptidoglycan was increased to improve the integrity of the cell wall via metabolizing glycine; By metabolizing glycine, the content of unsaturated fatty acid was increased, such as C19cyc11, to promote membrane fluidity. In addition, the metabolism of glycine could neutralize the acidic intracellular environment to reduce DNA damage, thus improve the survival rate of freeze-dried strain. These findings may provide a new idea for industrialization of LAB powder.