Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong.
Department of Microbiology, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
Appl Microbiol Biotechnol. 2018 Jul;102(14):6257-6267. doi: 10.1007/s00253-018-9083-5. Epub 2018 May 28.
Comparative transcriptome analysis was used to determine the differentially expressed genes in Escherichia coli during aerosolization from liquid suspension. Isogenic mutant studies were then used to examine the potential part played by some of these genes in bacterial survival in the air. Bioaerosols were sampled after 3 min of nebulization, which aerosolized the bacteria from the liquid suspension to an aerosol chamber (A0), and after further 30 min of airborne suspension in the chamber (A30). Bacteria at A0 showed 65 differentially expressed genes (30 downregulated and 35 upregulated) as compared to the original bacteria in the nebulizer. Droplet evaporation models predicted a drop in temperature in the bioaerosols, which coincides with the change in the expression of cold shock protein genes-cspB and cspG in the bacteria. The most notable group of differentially expressed genes was sorbitol transport and metabolism genes (srlABDEMR). Other genes associated with osmotic stress, nutrient limitation, DNA damage, and other stresses were differentially expressed in the bacteria at A0. After further airborne suspension, one gene (ypfM, which encodes a hypothetical protein with unknown function) was downregulated in the bacteria at A30 as compared to those at A0. Finally, isogenic mutants with either the dps or srlA gene deleted (both genes were upregulated at A0) had lower survival than the parental strain, which is a sign of their potential ability to protect the bacteria in the air.
采用比较转录组学分析方法，确定了大肠杆菌在从液体悬浮液中雾化过程中的差异表达基因。然后，通过同源突变体研究来研究这些基因中的一些在细菌在空气中存活中的潜在作用。在喷雾 3 分钟后从液体悬浮液中雾化到气溶胶室（A0）后，对生物气溶胶进行采样，然后在室内空气中再悬浮 30 分钟（A30）。与喷雾器中原始细菌相比，A0 处的细菌表现出 65 个差异表达基因（30 个下调和 35 个上调）。液滴蒸发模型预测生物气溶胶中的温度下降，这与细菌中冷休克蛋白基因 cspB 和 cspG 的表达变化相吻合。差异表达最显著的一组基因是山梨醇运输和代谢基因（srlABDEMR）。A0 处的细菌中还表达了其他与渗透胁迫、营养限制、DNA 损伤和其他应激相关的基因。进一步的空气悬浮后，与 A0 处的细菌相比，A30 处的细菌中有一个基因（ypfM，编码一个具有未知功能的假设蛋白）下调。最后，与野生型相比，dps 或 srlA 基因缺失的同源突变体（这两个基因在 A0 处均上调）的存活能力较低，这表明它们具有在空气中保护细菌的潜在能力。
