Modification of membrane properties and fatty acids biosynthesis-related genes in Escherichia coli and Staphylococcus aureus: Implications for the antibacterial mechanism of naringenin

Abstract

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.

Variations in cellular membrane fatty acid composition ofEscherichia coliin resistance to pulsed electric fields induced by eugenol

“…Both of them decreased as the EUG concentration increased, which was accompanied by an increase in membrane fluidity. These results were similar to those of the previous study, which have illustrated that the membrane fluidity of E. coli and S. aureus cells increased in the presence of naringenin (Wang et al, ).…”

“…However, the content of SFAs remained pretty close. Similar behaviours have been observed in previous studies (Wang et al, ).…”

“…Previous studies have indicated that external factors such as chemicals, temperature, pressure, ions, nutrients, and the growth phase of the microbial culture can change lipid composition (Denich, Beaudette, Lee, & Trevors, ). It was reported that the higher proportion of UFA and the lower proportion of CFA in the membrane of E. coli were induced as an adaptation to naringenin (Wang, Zeng, Wang, Brennan, & Gong, ).…”

Non‐thermal technologies and its current and future application in the food industry: a review

“…Non‐thermal technologies are able to inactivate microorganisms at ambient or moderate temperatures, but these processes require very high treatment intensities, or some use restrictions, such as lethal effect of HHP, PEF, US and IR technologies was related to the lower pH value. Moreover, the bacterial spores and highly resistant microorganism also can limit of lethal efficiency of single non‐thermal technologies, such as PEF technology (Wang et al ., ). In order to enhance the antimicrobial effect at the lower process intensities, combining non‐thermal technology with conventional preservation methods, antimicrobial agents or other non‐thermal treatments could be applied in the food industry, such as combining HPP with lacticin, or nisin, or PEF with ultrasonication co‐treatment (Ross et al ., ; Wang et al ., ).…”

Antibacterial activity of a hexahydro‐β‐acids/methyl‐β‐cyclodextrin inclusion complex against bacteria related to foodborne illness

“…Combined with Table , the change was more pronounced for S. aureus , which indicated that gram‐positive bacteria are more sensitive to HBA/M‐β‐CD than gram‐negative bacteria. This is likely due of the fact that gram‐negative bacteria have a thick layer of lipopolysaccharide outer membrane covering the cell wall, which serves to protect them from antibacterial agents (Liu et al, ; Ning et al, ; Wang, Zeng, Wang, Brennan, & Gong, ).…”