The effect of uracil on the freeze-drying survival rate of Lactiplantibacillus plantarum YR07 based on transcriptome analysis.

This study aimed to elucidate how adding uracil to the culture medium enhanced the freeze-drying resistance of Lactiplantibacillus plantarum YR07. The results showed that uracil significantly increased the number of viable cells and the freeze-drying survival rate of L. plantarum YR07 (P < 0.05). This effect was primarily achieved through the regulation of several key genes, including those involved in energy production (pyrR, pyrB, purQ, purN, adhE), cell barrier protection (fabG, serS), cell repair (oppA, uvrC), and oxidative stress response (cysK). Specifically, uracil promoted energy production and substrate availability by upregulating genes related to carbohydrate metabolism and purine biosynthesis. Additionally, uracil enhanced the synthesis of unsaturated fatty acids and glutamine biosynthesis by regulating the expression of genes related to the cell wall and membrane, thereby strengthening the physical protective barrier. Furthermore, by promoting the expression of genes involved in DNA and protein repair, uracil provided the raw materials necessary for cellular repair and helped restore damaged structures by influencing nucleotide metabolism and protein synthesis. Uracil also stimulated the production of sulfur-containing amino acids, which helped L. plantarum YR07 resist oxidative stress and reduce cellular damage. Together, these regulatory mechanisms significantly enhanced the adaptive capacity of L. plantarum YR07 under harsh environmental conditions.