Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea.
Biology Centre CAS, Institute of Hydrobiology, Na Sádkách 7, 370 05 České Budějovice, Czech Republic.
Food Res Int. 2022 Apr;154:111013. doi: 10.1016/j.foodres.2022.111013. Epub 2022 Feb 16.
Escherichia coli O157:H7 EDL933 exposed to low-shear modeled microgravity (LSMMG) and normal gravity (NG) was used for a transcriptomic analysis. The modified Gompertz model (R = 0.81-0.99) showed an increased growth rate of E. coli O157:H7 under LSMMG. The mechanism of this active growth was associated with highly upregulated genes in nutrient and energy metabolism, including the TCA cycle, glycolysis, and pyruvate metabolism. Green fluorescent protein-labeled E. coli O157:H7 also formed significantly thick biofilms (fluorescent unit: NG, 1,263; LSMMG, 1,533; P = 0.0473) under LSMMG, whereas bacterial mobility decreased slightly (P = 0.0310). The transcriptomic analysis revealed that genes encoding glycogen biosynthesis (glgCAP operon) were upregulated (1.40 to 1.82 of log fold change [FC]) due to the downregulation of csrA (2.17 of log FC), which is the global regulator of biofilm formation of E. coli. We also identified 52 genes in E. coli O157:H7 EDL933 that were involved in the secretion pathway, 32 of which showed ≥2-fold significant changes in transcription levels after cultivation under LSMMG. Notably, all downregulated genes belonged to the type III and VI secretion systems, indicating that host cell contact secretion was dysregulated in the LSMMG cultures compared to the NG cultures. LSMMG also stimulates the pathogenicity of E. coli O157:H7 via transcriptional upregulation of Shiga toxin 1 (1.36 to 2.81 log FC) and toxin HokB (6.1 log FC). Our results suggest LSMMG affects bacterial growth, biofilm formation, and E. coli O157:H7 pathogenicity at some transcriptional levels, which indicates the importance of understanding biological consequences.
大肠杆菌 O157:H7 EDL933 在低剪切模拟微重力 (LSMMG) 和正常重力 (NG) 下进行了转录组分析。修正的 Gompertz 模型 (R=0.81-0.99) 显示大肠杆菌 O157:H7 在 LSMMG 下的生长速率增加。这种活跃生长的机制与营养和能量代谢中高度上调的基因有关，包括 TCA 循环、糖酵解和丙酮酸代谢。绿色荧光蛋白标记的大肠杆菌 O157:H7 在 LSMMG 下也形成了明显较厚的生物膜（荧光单位：NG，1,263；LSMMG，1,533；P=0.0473），而细菌的迁移性略有下降（P=0.0310）。转录组分析显示，由于全局调控生物膜形成的 csrA（2.17 倍 log FC）下调，编码糖原生物合成（glgCAP 操纵子）的基因上调（1.40 到 1.82 倍 log FC）。我们还鉴定了大肠杆菌 O157:H7 EDL933 中 52 个参与分泌途径的基因，其中 32 个在 LSMMG 培养下转录水平发生了≥2 倍的显著变化。值得注意的是，所有下调的基因都属于 III 型和 VI 型分泌系统，表明与 NG 培养相比，LSMMG 培养中宿主细胞接触分泌受到了失调。LSMMG 通过转录上调志贺毒素 1（1.36 到 2.81 倍 log FC）和毒素 HokB（6.1 倍 log FC）也刺激大肠杆菌 O157:H7 的致病性。我们的结果表明，LSMMG 在某些转录水平上影响细菌的生长、生物膜形成和大肠杆菌 O157:H7 的致病性，这表明了解生物学后果的重要性。
