Cellular effects of monohydrochloride of l-arginine, Nalpha-lauroyl ethylester (LAE) on exposure to Salmonella typhimurium and Staphylococcus aureus

Abstract

a -lauroyl ethylester (LAE), a cationic preservative derived from lauric acid and arginine, on the cell envelopes of Salmonella typhimurium and Staphylococcus aureus at sub-lethal concentration such as their respective minimal inhibitory concentrations, 32 and 8 lg ml )1 , respectively. Methods and Results:Bacterial populations were studied by using transmission electron and fluorescence microscopy (TEM and FM), flow cytometry (FC) and ion-flux across the cellular membrane. Cell integrity was altered mainly in the outer membrane of S. typhimurium, but there was no significant change in the cytoplasm. However, in Staph. aureus, clear zones, abnormal septation and mesosome-like structures were observed in the cytoplasm. Bacterial populations were double-stained with propidium iodide (PI) and SYTO-13 for FC analysis. In S. typhimurium the proportion of damaged cells after 24 h was 97% and in Staph. aureus 56AE3%. LAE induced transmembrane ion flux, the increase of potassium leakage after 30 min of contact was 7AE7 and 3AE34 lg ml )1 for Staph. aureus and S. typhimurium, respectively. Membrane disruption was detected by measuring the proton flow across the membrane. Conclusions: Disturbance in membrane potential and structural changes was caused by LAE, although cells were not disrupted. Significance and Impact of the Study: This is the first time the cellular effects of LAE on bacterial cells were studied.

Antimicrobial Effectiveness of Lauroyl Arginate Incorporated into Ethylene Vinyl Alcohol Copolymers to Extend the Shelf-Life of Chicken Stock and Surimi Sticks

“…Micrographs showed that LAE produced important changes in the cell envelope, indicating that membranes are the main target, producing disruption and instability of the plasma membrane, and presenting more activity against Gram-positive bacteria than against Gram-negative bacteria according to results obtained by other authors (Rodriguez et al 2004). LAE interacts with lipids from the bacterial membranes, generating changes in membrane potential and bacterial structure in Gram-negative bacteria (Rodriguez et al 2004).…”

“…Data are represented as mean ± standard deviation. SYTO-13 penetrates all types of cellular membranes and binds nucleic acids of the cell, whereas PI only penetrates the bacterial membrane when the membrane is damaged (Rodriguez et al 2004). The percentage of cell death in the control is due to different phases of cellular cycle.…”

“…LAE interacts with lipids from the bacterial membranes, generating changes in membrane potential and bacterial structure in Gram-negative bacteria (Rodriguez et al 2004). Cell lysis was not observed.…”

Opinion of the Scientific Panel on food additives, flavourings, processing aids and materials in contact with food (AFC) related to an application on the use of ethyl lauroyl arginate as a food additive

“…One consequence of the interaction between ethyl lauroyl arginate and microorganisms is the denaturation of membrane proteins resulting in increased membrane permeability. This can result in the inhibition of growth or the death of the microorganism (Rodríguez et al, 2004).…”

“…One consequence of the interaction between ethyl lauroyl arginate and microorganisms is the denaturation of membrane proteins resulting in increased membrane permeability. This can result in the inhibition of growth or the death of the microorganism (Rodríguez et al, 2004).Ethyl lauroyl arginate is proposed to be used in the following food categories up to the maximum levels indicated in Table 1. The Panel notes that Table 1 includes proposed uses in meat products and salted dry fish despite stability experiments demonstrating limited stability of ethyl-N α -lauroyl-L-arginate in these foods.…”