Qiao Hui, You Mingkun, Yan Jiaming, Zhang Meng, Lai-Yu Kwok, Zhang Wenyi
Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, People's Republic of China.
Key Laboratory of Dairy Products Processing, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot, People's Republic of China.
NPJ Sci Food. 2025 May 19;9(1):78. doi: 10.1038/s41538-025-00409-8.
Freeze-drying is a widely adopted method for the long-term storage of starter cultures in the food industry but can cause cell instability and a decline in post-storage viability. We used an unmethylated Lacticaseibacillus paracasei Zhang mutant lacking adenine-specific DNA-methyltransferase. This mutant was subjected to freeze-drying and stored at 30 °C for two distinct durations (30 and 60 days), Our analysis revealed the unmethylated mutant outperformed the wild-type in cell viability and survival following freeze-drying and post-freeze-drying storage. And significant metabolic pathway differences between the stored mutant and wild-type bacteria. These differences were evident in the phosphotransferase system, carbohydrate, and amino acid metabolism, and fatty acid biosynthesis, and were consistent across transcriptomic, proteomic, and metabolomic analyses. This is achieved by modulating key metabolic pathways within the bacteria. This study contributes to the limited literature on the role of bacterial adenine methylation in industrial strain application and starter culture storage.
冷冻干燥是食品工业中广泛采用的一种用于长期保存发酵剂培养物的方法，但它可能会导致细胞不稳定以及储存后活力下降。我们使用了一种缺乏腺嘌呤特异性DNA甲基转移酶的未甲基化副干酪乳杆菌张突变体。将该突变体进行冷冻干燥，并在30°C下储存两个不同的时间段（30天和60天），我们的分析表明，未甲基化突变体在冷冻干燥及冷冻干燥后储存期间的细胞活力和存活率方面优于野生型。并且储存的突变体和野生型细菌之间存在显著的代谢途径差异。这些差异在磷酸转移酶系统、碳水化合物、氨基酸代谢以及脂肪酸生物合成中很明显，并且在转录组学、蛋白质组学和代谢组学分析中是一致的。这是通过调节细菌内的关键代谢途径来实现的。本研究为关于细菌腺嘌呤甲基化在工业菌株应用和发酵剂培养物储存中的作用的有限文献做出了贡献。
