Kim Jisun, Shin Bora, Park Chulwoo, Park Woojun
Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul Korea.
Front Microbiol. 2017 Mar 14;8:433. doi: 10.3389/fmicb.2017.00433. eCollection 2017.
Indole, which is widespread in microbial communities, has received attention because of its effects on bacterial physiology. and can acquire ampicillin (Amp) resistance during growth on indole-Amp agar. Transcriptome, mutant, and inhibitor studies have suggested that Amp resistance induced by indole can be attributed to increased gene expression of encoding two genes of RND-type multidrug efflux operons and an encoding β-lactamase. Expression, enzyme activities, and mutational analyses indicated that AmpC β-lactamase is important for acquiring Amp resistance of in the presence of indole. Here, we show, for the first time, that volatile indole increased Amp-resistant cells. Consistent with results of the volatile indole assay, a low concentration of indole in liquid culture promoted growth initially, but led to mutagenesis after indole was depleted, which could not be observed at high indole concentrations. Interestingly, and gene expression levels correlate with the concentration of indole, which might explain the low number of Amp-mutated cells in high indole concentrations. The expression levels of genes involved in mutagenesis, namely , , and , were also modulated by indole. Our data indicates that indole reduces Amp-induced heterogeneity by promoting expression of TtgABC or MexAB-OprM efflux pumps and the indole-induced β-lactamase in and .
吲哚广泛存在于微生物群落中，因其对细菌生理学的影响而受到关注。[细菌名称]在吲哚 - 氨苄青霉素琼脂上生长时可获得氨苄青霉素（Amp）抗性。转录组、突变体和抑制剂研究表明，吲哚诱导的Amp抗性可归因于编码RND型多药外排操纵子的两个基因的基因表达增加以及编码β-内酰胺酶的[基因名称]的表达增加。表达、酶活性和突变分析表明，AmpCβ-内酰胺酶对于[细菌名称]在吲哚存在下获得Amp抗性很重要。在此，我们首次表明挥发性吲哚增加了Amp抗性细胞。与挥发性吲哚测定结果一致，液体培养中低浓度的吲哚最初促进生长，但在吲哚耗尽后导致诱变，而在高吲哚浓度下未观察到这种情况。有趣的是，[相关基因名称]的基因表达水平与吲哚浓度相关，这可能解释了高吲哚浓度下Amp突变细胞数量较少的原因。参与诱变的基因，即[相关基因名称]的表达水平也受到吲哚的调节。我们的数据表明，吲哚通过促进TtgABC或MexAB - OprM外排泵以及吲哚诱导的β-内酰胺酶在[细菌名称]中的表达来降低Amp诱导的异质性。
