Untargeted metabolomics and physiological phenotypic analyses reveal the defense strategies of nitrite by Lactiplantibacillus plantarum PK25

A comprehensive understanding of the defense strategies against nitrite by Lactiplantibacillus plantarum remains unknown. Herein, the effects of nitrite degradation process on metabolic profiling of L. plantarum PK25 were investigated by metabolomics and phenomenological measurement. A total of 633 metabolites were significantly different at 6, 12, and 24 incubation hours. Specifically, citrulline and lysine reduction facilitated strain survival by limiting cell growth. A significant reduction of unsaturated fatty acids was observed, which could induce reduced cell membrane fluidity to prevent nitrite entry. The accumulation of thymine and cytosine might be resulted from accelerated RNA expression to accelerate the repair of cells. Dopamine and ergothioneine could serve as antioxidants to prevent bacteria from oxidative stress. Furthermore, cell filamentation production, increased hydrophobicity, and altered antioxidant enzyme activity were favorable alterations made by strain. Our study demonstrated the metabolite profile alteration of L. plantarum during nitrite degradation, which provided a theoretical basis for targeting strain function.