Heo Aram, Jang Hyun-Jin, Sung Jung-Suk, Park Woojun
Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea.
Department of Life Science, Dongguk University, Seoul, Republic of Korea.
PLoS One. 2014 Oct 17;9(10):e110215. doi: 10.1371/journal.pone.0110215. eCollection 2014.
The effects of antibiotics on environment-originated nonpathogenic Acinetobacter species have been poorly explored. To understand the antibiotic-resistance mechanisms that function in nonpathogenic Acinetobacter species, we used an RNA-sequencing (RNA-seq) technique to perform global gene-expression profiling of soil-borne Acinetobacter oleivorans DR1 after exposing the bacteria to 4 classes of antibiotics (ampicillin, Amp; kanamycin, Km; tetracycline, Tc; norfloxacin, Nor). Interestingly, the well-known two global regulators, the soxR and the rpoE genes are present among 41 commonly upregulated genes under all 4 antibiotic-treatment conditions. We speculate that these common genes are essential for antibiotic resistance in DR1. Treatment with the 4 antibiotics produced diverse physiological and phenotypic changes. Km treatment induced the most dramatic phenotypic changes. Examination of mutation frequency and DNA-repair capability demonstrated the induction of the SOS response in Acinetobacter especially under Nor treatment. Based on the RNA-seq analysis, the glyoxylate-bypass genes of the citrate cycle were specifically upregulated under Amp treatment. We also identified newly recognized non-coding small RNAs of the DR1 strain, which were also confirmed by Northern blot analysis. These results reveal that treatment with antibiotics of distinct classes differentially affected the gene expression and physiology of DR1 cells. This study expands our understanding of the molecular mechanisms of antibiotic-stress response of environment-originated bacteria and provides a basis for future investigations.
抗生素对源自环境的非致病性不动杆菌属细菌的影响尚未得到充分研究。为了解在非致病性不动杆菌属细菌中起作用的抗生素抗性机制，我们使用RNA测序（RNA-seq）技术，对土壤源食油不动杆菌DR1在暴露于4类抗生素（氨苄青霉素，Amp；卡那霉素，Km；四环素，Tc；诺氟沙星，Nor）后的全基因组基因表达谱进行了分析。有趣的是，在所有4种抗生素处理条件下，41个共同上调的基因中存在两个著名的全局调节因子，即soxR和rpoE基因。我们推测这些共同基因对于DR1中的抗生素抗性至关重要。用这4种抗生素处理产生了多种生理和表型变化。Km处理诱导的表型变化最为显著。对突变频率和DNA修复能力的检测表明，不动杆菌中诱导了SOS反应，尤其是在Nor处理下。基于RNA-seq分析，柠檬酸循环的乙醛酸旁路基因在Amp处理下特异性上调。我们还鉴定了DR1菌株新识别出的非编码小RNA，这也通过Northern印迹分析得到了证实。这些结果表明，用不同类别的抗生素处理对DR1细胞的基因表达和生理有不同的影响。本研究扩展了我们对环境源细菌抗生素应激反应分子机制的理解，并为未来的研究提供了基础。
