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Plectasin is a cationic antimicrobial peptide (AMP) that is 40 residues long and belongs to the cysteine-stabilized α-helix and β-sheet superfamily. This peptide, which was first isolated from the saprophytic fungus Pseudoplectania nigrella , exhibits strong bactericidal activity toward several gram-positive pathogens, including Staphylococcus aureus and Streptococcus pneumoniae . In this review, we discuss the latest advances made to improve plectasin antimicrobial activity and reduce its cytotoxicity, namely a variety of methods for the design and construction of plectasin derivatives, hybrids, and available expression systems. In addition, we focused on the investigations regarding the biological activity, therapeutic properties, and mechanisms of action of this promising antibiotic. [ABSTRACT FROM AUTHOR]

This work is the first to report the antibacterial characteristics and antibacterial mechanisms of MP1102, which is a variant of NZ2114, against pathogenic Clostridium perfringens. MP1102 exhibited strong antimicrobial activity against C. perfringens strains CVCC 61, CVCC 1163, and CVCC 2032 at a low minimal inhibitory concentration (MIC) of 0.91 μM. MP1102 showed anti- C. perfringens activity over a wide pH range of 2.0 and 10.0, high thermal stability from 20 to 80 °C, and remarkable resistance to pepsin. The fractional inhibitory concentration index (FICI) indicated an additive or synergic effect between MP1102 and bacitracin zinc, nisin, vancomycin, virginiamycin, aureomycin, and ampicillin against C. perfringens (FICI = 0.3125-1.0). To further elucidate the antibacterial mechanism of MP1102, its effect on the C. perfringens CVCC 61 cell membrane and intracellular DNA was studied. Flow cytometry and scanning electron microscopy (SEM) indicated that MP1102 treatment resulted in the release of cellular contents by damaging the membrane. A DNA gel retardation and circular dichroism analysis demonstrated that MP1102 interacted with DNA and intercalated into the DNA base pairs. A cell cycle assay demonstrated that MP1102 affected cellular functions, such as DNA synthesis. These results suggested that MP1102 exhibited potential as a new antimicrobial agent against C. perfringens infections. [ABSTRACT FROM AUTHOR]