Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kongens, Lyngby, Denmark.
Microbiology (Reading). 2020 Feb;166(2):141-148. doi: 10.1099/mic.0.000867. Epub 2019 Oct 18.
The ability of to tolerate acid stress is important for its survival and colonization in the human digestive tract. Here, we performed adaptive laboratory evolution of the laboratory strain K-12 MG1655 at pH 5.5 in glucose minimal medium. After 800 generations, six independent populations under evolution had reached 18.0 % higher growth rates than their starting strain at pH 5.5, while maintaining comparable growth rates to the starting strain at pH 7. We characterized the evolved strains and found that: (1) whole genome sequencing of isolated clones from each evolved population revealed mutations in appearing in five of six sequenced clones; and (2) gene expression profiles revealed different strategies to mitigate acid stress, which are related to amino acid metabolism and energy production and conversion. Thus, a combination of adaptive laboratory evolution, genome resequencing and expression profiling revealed, on a genome scale, the strategies that uses to mitigate acid stress.
在人类消化道中，耐受酸应激的能力对于的生存和定植非常重要。在这里，我们在 pH 值为 5.5 的葡萄糖最小培养基中对实验室菌株 K-12 MG1655 进行了适应性实验室进化。经过 800 代，六个独立的进化种群在 pH 值为 5.5 时的生长速度比起始菌株高 18.0%，同时保持与起始菌株在 pH 值为 7 时的生长速度相当。我们对进化后的菌株进行了表征，发现：（1）从每个进化种群中分离出的克隆的全基因组测序显示，在六个测序克隆中有五个出现了 中的突变；（2）基因表达谱显示了不同的缓解酸应激的策略，这些策略与氨基酸代谢以及能量的产生和转化有关。因此，适应性实验室进化、基因组重测序和表达谱分析的结合，从基因组水平上揭示了 缓解酸应激的策略。
