基于非靶向代谢组学分析甲基化对副干酪乳酪杆菌发酵剂贮藏特性的影响

Effect of Methylation on Storage Properties of Lacticaseibacillus paracasei as Analyzed by Untargeted Metabolomics

副干酪乳酪杆菌(Lacticaseibacillus paracasei)Zhang是一株具有调节免疫反应、抗氧化等益生特性的优良菌株。DNA甲基化是一种重要的表观遗传机制,在细菌的很多生理过程中发挥关键作用。为更好利用该菌株,本研究重点关注甲基化对L.paracasei Zhang发酵剂贮藏特性的影响。利用L.paracasei Zhang及其DNA甲基化突变株ΔpglX制备发酵剂并在30℃条件下贮藏90 d。结果表明:与野生型相比,甲基化突变株在贮藏90 d后活菌数极显著提高(P<0.01);利用非靶向代谢组学方法分析贮藏90 d后野生型及其甲基化突变体的代谢物差异发现,与野生型相比,突变体的差异代谢物质有269种,在负离子模式下主要富集到核苷酸代谢、嘌呤代谢、嘧啶代谢、柠檬酸循环、乙醛酸盐和二羧酸盐代谢等多条代谢通路,在正离子模式下主要富集到生物素代谢等多条代谢通路。研究结果证实DNA甲基化可以通过生成和利用碳水化合物类、脂肪酸类物质等提高L.paracasei Zhang的贮藏特性。

Lacticaseibacillus paracasei Zhang is an excellent strain with probiotic properties such as immunomodulatory and antioxidant activities.DNA methylation is an important epigenetic mechanism that plays a key role in many physiological processes in bacteria.In order to better utilize the strain,this study focused on the effect of methylation on the storage properties of two starter cultures of L.paracasei Zhang and its DNA methylation mutant(ΔpglX)at 30℃.The results showed that after 90 d of storage,the viable number of the mutant significantly increased compared with the wild type(P<0.01).Using untargeted metabolomics,269 differential metabolites were observed in the mutant compared with the wild type,which were mainly enriched in the nucleotide metabolism,purine metabolism,pyrimidine metabolism,citrate cycle,glyoxylate,and dicarboxylate metabolism pathways in the negative ion mode.In the positive ion mode,they were mainly enriched in the biotin metabolism pathway.These findings confirmed that DNA methylation could improve the storage properties of L.paracasei Zhang through the generation and utilization of carbohydrates and fatty acids.