School of Food Science and Engineering, South China University of Technology, Guangzhou 510641, China.
School of Food Science and Engineering, South China University of Technology, Guangzhou 510641, China.
Biochim Biophys Acta Biomembr. 2018 Feb;1860(2):481-490. doi: 10.1016/j.bbamem.2017.11.007. Epub 2017 Nov 11.
In this work, modifications of cell membrane fluidity, fatty acid composition and fatty acid biosynthesis-associated genes of Escherichia coli ATCC 25922 (E. coli) and Staphylococcus aureus ATCC 6538 (S. aureus), during growth in the presence of naringenin (NAR), one of the natural antibacterial components in citrus plants, was investigated. Compared to E. coli, the growth of S. aureus was significantly inhibited by NAR in low concentrations. Combination of gas chromatography-mass spectrometry with fluorescence polarization analysis revealed that E. coli and S. aureus cells increased membrane fluidity by altering the composition of membrane fatty acids after exposure to NAR. For example, E. coli cells produced more unsaturated fatty acids (from 18.5% to 43.3%) at the expense of both cyclopropane and saturated fatty acids after growth in the concentrations of NAR from 0 to 2.20mM. For S. aureus grown with NAR at 0 to 1.47mM, the relative proportions of anteiso-branched chain fatty acids increased from 37.2% to 54.4%, whereas iso-branched and straight chain fatty acids decreased from 30.0% and 33.1% to 21.6% and 23.7%, respectively. Real time q-PCR analysis showed that NAR at higher concentrations induced a significant down-regulation of fatty acid biosynthesis-associated genes in the bacteria, with the exception of an increased expression of fabA gene. The minimum inhibitory concentration (MIC) of NAR against these two bacteria was determined, and both of bacteria underwent morphological changes after exposure to 1.0 and 2.0 MIC.
本工作研究了在存在柚皮素（NAR）的情况下，大肠杆菌 ATCC 25922（E. coli）和金黄色葡萄球菌 ATCC 6538（S. aureus）的细胞膜流动性、脂肪酸组成和脂肪酸生物合成相关基因的变化，NAR 是柑橘类植物中天然抗菌成分之一。与 E. coli 相比，S. aureus 的生长在低浓度 NAR 存在下受到明显抑制。气相色谱-质谱联用与荧光偏振分析表明，E. coli 和 S. aureus 细胞在暴露于 NAR 后通过改变膜脂肪酸的组成来增加膜流动性。例如，E. coli 细胞在 NAR 浓度从 0 增加到 2.20mM 的过程中产生了更多的不饱和脂肪酸（从 18.5%增加到 43.3%），而同时环丙烷和饱和脂肪酸的比例下降。对于在 0 至 1.47mM NAR 下生长的 S. aureus，支链脂肪酸的相对比例从前体异戊烯基增加到 54.4%，而异型和直链脂肪酸的比例从 30.0%和 33.1%分别下降到 21.6%和 23.7%。实时 q-PCR 分析表明，较高浓度的 NAR 诱导细菌中脂肪酸生物合成相关基因的显著下调，除 fabA 基因的表达增加外。测定了 NAR 对这两种细菌的最低抑菌浓度（MIC），并且在暴露于 1.0 和 2.0 MIC 后，两种细菌都发生了形态变化。
