title: Evaluation of morphological changes of Staphylococcus aureus and Escherichia coli induced with the antimicrobial peptide AN5-1.
abstract: The mechanisms of action of AN5-1 against Gram-negative and Gram-positive bacteria were investigated by evaluations of the intracellular content leakage and by microscopic observations of the treated cells. Escherichia coli and Staphylococcus aureus were used for this investigation. Measurements of DNA, RNA, proteins, and β-galactosidase were taken, and the results showed a significant increase in the cultivation media after treatment with AN5-1 compared with the untreated cells. The morphological changes of treated cells were shown using transmission electron microscopy (TEM) and atomic force microscopy (AFM). The observations showed that AN5-1 acts against E. coli and against S. aureus in similar ways, by targeting the cell wall, causing disruptions; at a high concentration (80 AU/ml), these disruptions led to cell lysis. The 3D AFM imaging system showed that at a low concentration of 20 AU/ml, the effect of AN5-1 is restricted to pore formation only. Moreover, a separation between the cell wall and the cytoplasm was observed when Gram-negative bacteria were treated with a low concentration (20 AU/ml) of AN5-1.
authors.affiliation: Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia, bassamalkotaini@gmail.com.
authors.forename: Bassam
authors.initials: B
authors.lastname: Alkotaini
authors.forename: Nurina
authors.initials: N
authors.lastname: Anuar
authors.forename: Abdul Amir Hassan
authors.initials: AA
authors.lastname: Kadhum
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000302:isolation & purification / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure*; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D056507:Paenibacillus / Q000737:chemistry; D012329:RNA, Bacterial / Q000378:metabolism; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure*; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D001616:beta-Galactosidase