Key Laboratory of Food Nutrition and Safety, Ministry of Education, Food Engineering and Biotechnology Institute, Tianjin University of Science & Technology, Tianjin, 300457, China.
Chinese medical college of TJUTCM, Tianjin University of Traditional Chinese Medicine, Tianjin, 300193, China.
Sci Rep. 2017 Oct 9;7(1):12827. doi: 10.1038/s41598-017-12916-0.
It is important for probiotics that are currently utilized in the dairy industry to have clear genetic backgrounds. In this study, the genetic characteristics of Lactobacillus kefiranofaciens ZW3 were studied by undertaking a comparative genomics study, and key genes for adaptation to different environments were investigated and validated in vitro. Evidence for horizontal gene transfer resulting in strong self-defense mechanisms was detected in the ZW3 genome. We identified a series of genes relevant for dairy environments and the intestinal tract, particularly for extracellular polysaccharide (EPS) production. Reverse transcription-qPCR (RT-qPCR) revealed significant increases in the relative expression of pgm, ugp, and uge during the mid-logarithmic phase, whereas the expression of pgi was higher at the beginning of the stationary phase. The enzymes encoded by these four genes concertedly regulated carbon flux, which in turn modulated the production of EPS precursors. Moreover, ZW3 tolerated pH 3.5 and 3% bile salt and retained cell surface hydrophobicity and auto-aggregation. In conclusion, we explored the potential of ZW3 for utilization in both the dairy industry and in probiotic applications. Additionally, we elucidated the regulation of the relevant genes involved in EPS production.
对于当前应用于乳制品行业的益生菌而言，具有明确的遗传背景非常重要。在本研究中，通过比较基因组学研究，对植物乳杆菌 ZW3 的遗传特性进行了研究，并在体外对适应不同环境的关键基因进行了研究和验证。在 ZW3 基因组中检测到了水平基因转移导致的强大自我防御机制的证据。我们鉴定了一系列与乳制品环境和肠道相关的基因，特别是与胞外多糖（EPS）生产相关的基因。逆转录 qPCR（RT-qPCR）显示，在对数中期，pgm、ugp 和 uge 的相对表达显著增加，而 pgi 的表达在静止期开始时更高。这四个基因编码的酶协同调节碳通量，从而调节 EPS 前体的产生。此外，ZW3 耐受 pH3.5 和 3%胆汁盐，并保持细胞表面疏水性和自聚集性。总之，我们探索了 ZW3 在乳制品工业和益生菌应用中的潜力，并阐明了与 EPS 生产相关的相关基因的调控。
