The effect of aspartic acid on the freeze-drying survival rate of Lactobacillus plantarum LIP-1 and its inherent mechanism.

Amino acids are often used as growth factors to promote the growth of strains, but we found that adding aspartic acid to the medium could significantly improve the freeze-drying survival rate of some Lactobacillus plantarum (p < 0.05). Our research aimed at Lactobacillus plantarum LIP-1, after exploring its internal mechanism, it is proved that the addition of aspartic acid could significantly reduce the strain's cell wall, cell membrane and DNA damage during the freeze-drying process. Further research concluded some critical points after adding aspartic acid into a medium as below: reduce cell wall damage by increasing the peptidoglycan content, protect the integrity of the cell membrane by increasing the content of long-chain fatty acids, unsaturated fatty acids and cyclopropane fatty acids in cell membranes, and reduce DNA damage by increasing the intracellular pH. Further studies are needed on improving the freeze-drying survival of strains by altering the composition of culture media. • Aspartic acid could improve survival rate of strain during freeze-drying. • Aspartic acid reduced the damage of strain during freeze drying process. • Aspartic acid could increase the peptidoglycan content in the cell wall. • Aspartic acid could adjust fatty acid composition of the cell membrane. • Aspartic acid reduced DNA damage by increasing intracellular pH. [ABSTRACT FROM AUTHOR]