Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium.
BMC Genomics. 2010 Feb 5;11:90. doi: 10.1186/1471-2164-11-90.
Burkholderia cepacia complex bacteria are opportunistic pathogens, which can cause severe respiratory tract infections in patients with cystic fibrosis (CF). As treatment of infected CF patients is problematic, multiple preventive measures are taken to reduce the infection risk. Besides a stringent segregation policy to prevent patient-to-patient transmission, clinicians also advise patients to clean and disinfect their respiratory equipment on a regular basis. However, problems regarding the efficacy of several disinfection procedures for the removal and/or killing of B. cepacia complex bacteria have been reported. In order to unravel the molecular mechanisms involved in the resistance of biofilm-grown Burkholderia cenocepacia cells against high concentrations of reactive oxygen species (ROS), the present study focussed on the transcriptional response in sessile B. cenocepacia J2315 cells following exposure to high levels of H2O2 or NaOCl.
The exposure to H2O2 and NaOCl resulted in an upregulation of the transcription of 315 (4.4%) and 386 (5.4%) genes, respectively. Transcription of 185 (2.6%) and 331 (4.6%) genes was decreased in response to the respective treatments. Many of the upregulated genes in the NaOCl- and H2O2-treated biofilms are involved in oxidative stress as well as general stress response, emphasizing the importance of the efficient neutralization and scavenging of ROS. In addition, multiple upregulated genes encode proteins that are necessary to repair ROS-induced cellular damage. Unexpectedly, a prolonged treatment with H2O2 also resulted in an increased transcription of multiple phage-related genes. A closer inspection of hybridisation signals obtained with probes targeting intergenic regions led to the identification of a putative 6S RNA.
Our results reveal that the transcription of a large fraction of B. cenocepacia J2315 genes is altered upon exposure of sessile cells to ROS. These observations have highlighted that B. cenocepacia may alter several pathways in response to exposure to ROS and they have led to the identification of many genes not previously implicated in the stress response of this pathogen.
洋葱伯克霍尔德氏菌复合群是一种机会性病原体，可导致囊性纤维化 (CF) 患者发生严重的呼吸道感染。由于对感染 CF 患者的治疗存在问题，因此采取了多种预防措施来降低感染风险。除了严格的隔离政策以防止患者之间的传播外，临床医生还建议患者定期清洁和消毒呼吸设备。然而，已经报道了几种用于去除和/或杀死洋葱伯克霍尔德氏菌复合群细菌的消毒程序的功效问题。为了揭示生物膜生长的洋葱伯克霍尔德氏菌对高浓度活性氧 (ROS) 产生抗性的分子机制，本研究集中于暴露于高浓度 H2O2 或 NaOCl 后静止的 B. cenocepacia J2315 细胞的转录反应。
暴露于 H2O2 和 NaOCl 分别导致 315（4.4%）和 386（5.4%）个基因的转录上调。分别用相应的处理方法处理时，185（2.6%）和 331（4.6%）个基因的转录下调。在 NaOCl 和 H2O2 处理的生物膜中上调的许多基因都参与氧化应激以及一般应激反应，这强调了有效中和和清除 ROS 的重要性。此外，多个上调的基因编码了修复 ROS 诱导的细胞损伤所需的蛋白质。出乎意料的是，H2O2 的长时间处理也导致多个噬菌体相关基因的转录增加。用针对基因间区的探针进行杂交信号的仔细检查导致鉴定出一种假定的 6S RNA。
我们的结果表明，在暴露于 ROS 时，静止细胞的大部分 B. cenocepacia J2315 基因的转录发生改变。这些观察结果表明，B. cenocepacia 可能会在暴露于 ROS 时改变几种途径，并确定了许多以前未涉及该病原体应激反应的基因。
