Erythorbyl laurate as a potential food additive with multi-functionalities: Antibacterial activity and mode of action

Abstract Background: Though many plant defensins exhibit antibacterial activity, little is known about their antibacterial mode of action (MOA). Antimicrobial peptides with a characterized MOA induce the expression of multiple bacterial outer membrane modifications, which are required for resistance to these membrane-targeting peptides. Mini-Tn5-lux mutant strains of Pseudomonas aeruginosa with Tn insertions disrupting outer membrane protective modifications were assessed for sensitivity against plant defensin peptides. These transcriptional lux reporter strains were also evaluated for lux gene expression in response to sublethal plant defensin exposure. Also, a plant pathogen, Pseudomonas syringae pv. syringae was modified through transposon mutagenesis to create mutants that are resistant to in vitro MtDef4 treatments.Results: Plant defensins displayed specific and potent antibacterial activity against strains of P. aeruginosa. A defensin from Medicago truncatula, MtDef4, induced dose-dependent gene expression of the aminoarabinose modification of LPS and surface polycation spermidine production operons. The ability for MtDef4 to damage bacterial outer membranes was also verified visually through fluorescent microscopy. Another defensin from M. truncatula, MtDef5, failed to induce lux gene expression and limited outer membrane damage was detected with fluorescent microscopy. The transposon insertion site on MtDef4 resistant P. syringae pv. syringae mutants was sequenced, and modifications of ribosomal genes were identified to contribute to enhanced resistance to plant defensin treatments. Conclusions: MtDef4 damages the outer membrane similar to polymyxin B, which stimulates antimicrobial peptide resistance mechanisms to plant defensins. MtDef5, appears to have a different antibacterial MOA. Additionally, the MtDef4 antibacterial mode of action may also involve inhibition of translation.

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Zinc oxide microrods and nanorods: different antibacterial activity and their mode of action against Gram-positive bacteria

RSC Advances ◽

10.1039/c4ra08462d ◽

2014 ◽

Vol 4 (99) ◽

pp. 56031-56040 ◽

Cited By ~ 42

Author(s):

Ilaria Rago ◽

Chandrakanth Reddy Chandraiahgari ◽

Maria P. Bracciale ◽

Giovanni De Bellis ◽

Elena Zanni ◽

...

Keyword(s):

Zinc Oxide ◽

Antibacterial Activity ◽

Mode Of Action ◽

Gram Positive ◽

Gram Positive Bacteria

ZnO micro and nanorods, produced through simple and inexpensive techniques, resulted to be strong antimicrobials against Gram-positive bacteria, in vitro as well as in vivo, by altering cell outer structures like membrane and exopolysaccharides.

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Antibacterial Activity, Cytotoxicity, and the Mechanism of Action of Bacteriocin from Bacillus subtilis GAS101

Medical Principles and Practice ◽

10.1159/000487306 ◽

2018 ◽

Vol 27 (2) ◽

pp. 186-192 ◽

Cited By ~ 11

Author(s):

Garima Sharma ◽

Shweta Dang ◽

Sanjay Gupta ◽

Reema Gabrani

Keyword(s):

Molecular Weight ◽

Antibacterial Activity ◽

Bacillus Subtilis ◽

Vero Cell ◽

Cell Line ◽

Mode Of Action ◽

Proteolytic Enzymes ◽

Antibiofilm Activity ◽

Vero Cell Line ◽

Soil Isolate

Objective: The aim of this study was to purify and characterize bacteriocin from the soil isolate Bacillus subtilis GAS101, and to determine its antimicrobial as well as antibiofilm potential. The purified bacteriocin was further analyzed and evaluated for mammalian cell cytotoxicity and the possible mode of action. Material and Methods: Bacteriocin from B. subtilis GAS101 (an animal husbandry soil isolate) was partially purified and checked for antimicrobial and antibiofilm activity against gram-positive and gram-negative bacteria. The molecular weight of bacteriocin was determined using tricine SDS-PAGE gel. The stability of bacteriocin was investigated at various temperatures and pH levels, and its sensitivity towards 8 enzymes and 6 chemicals was determined. Cytotoxicity analysis was performed on a Vero cell line by a tetrazolium dye-based assay. Scanning electron microscopy (SEM) of bacteriocin-treated bacteria was carried out to determine the possible mode of action. Results: Bacteriocin from B. subtilis GAS101 was a potential inhibitor of both the indicator organisms (Staphylococcus epidermidis and Escherichia coli), and had a molecular weight of approximately 6.5 kDa. An in situ gel assay showed a zone of inhibition corresponding to the estimated protein band size. Bacteriocin was stable and showed antibacterial activity in broad ranges of temperature (30–121°C) and pH (2–12). It was sensitive to 4 proteolytic enzymes, which indicated its proteinaceous nature. Bacteriocin showed > 70% cell viability on the mammalian Vero cell line. SEM depicted that the bacteriocin was able to disrupt the bacterial cell membrane as its probable mode of action. Conclusion: Thermostable and pH-tolerant bacteriocin from B. subtilis GAS101, of about 6.5 kDa, showed broad-spectrum antimicrobial and antibiofilm activity.

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