Cellular and proteomic responses of Escherichia coli JK-17 exposed to the Rosa hybrida flower extract

Abstract

The purpose of this work was to characterize the cellular and proteomic responses of Escherichia coli JK-17 exposed to the rose flower extract (Rosa hybrida). The bacterial isolate was enriched and isolated from contaminated food. 16S rRNA sequence analyses revealed that the strain was 99% similar to the E. coli species cluster; therefore, this strain was designated E. coli JK-17. The rose flower extract showed a dose-dependent antibacterial effect on E. coli JK-17. Treatment of E. coli JK-17 with 50 and 100 mg/mL of the rose flower extract completely inhibited growth within 12 and 6 h of incubation. The stress shock proteins (SSPs) were induced with different concentrations of rose flower extract. The proteins were identified as 70-kDa DnaK and 60-kDa GroEL by SDS-PAGE and Western blot using anti-DnaK and antiGroEL monoclonal antibodies. The levels of SSPs induced by the rose flower extract increased when the exposure time to the rose flower extract was increased. SDS-PAGE with silver staining revealed that the amount of lipopolysaccharide (LPS) in E. coli JK-17 increased or decreased with different concentrations and exposure times of the rose flower extract. To identify proteins induced by the rose flower extract, 2-dimensional electrophoresis (2-DE) was applied to soluble protein fractions of E. coli JK-17 cultures. In the pH range of 4 ~ 7, more than 250 spots were detected on the silver stained gels. Notably, 15 protein spots were increased or decreased after treatment with the rose flower extract. Twelve up-regulated proteins were identified as chaperones (DnaK and GroEL) and porin proteins (PhoE, RfaI, RfaG, MdoH, and WzzE) by MALDI-TOF mass spectrometry, and three down-regulated proteins were identified, including proteins involved in energy and DNA metabolism (SdhA and GyrB), and amino acid biosynthesis (GltK). Using scanning electron microscopic analysis, some cells were shown to adopt irregular rod shapes and wrinkled surfaces after treatment with the rose flower extract. These results provide clues for better understanding the mechanism of rose flower extract-induced stress and cytotoxicity in E. coli JK-17.

iTRAQ Proteomic Analysis Reveals That Metabolic Pathways Involving Energy Metabolism Are Affected by Tea Tree Oil in Botrytis cinerea

“…Proteomics can be used to study the changes in protein levels under stress conditions in great detail (Franco et al, 2013 ), and has been applied to investigate the mode of action of the antimicrobial agent apidaecin IB against membrane proteins in E. coli cells (Zhou and Chen, 2011 ). Other studies have revealed that proteins related to energy and DNA metabolism, and amino acid biosynthesis are down-regulated in E. coli JK-17 in the presence of rose flower extract (Cho and Oh, 2011 ). Syzygium aromaticum essential oil perturbs the expression of virulence-related genes involved in the synthesis of serine protease, flagella, and lipopolysaccharide in Campylobacter jejuni (Kovács et al, 2016 ).…”