Antibiotic resistance is a continuously increasing concern for public health care. Understanding resistance mechanisms and their emergence is crucial for the development of new antibiotics and their effective use. Here, we report the discovery of a gene amplification-based mechanism that imparts an up to 1000-fold increase in resistance levels against the antibiotic albicidin. We show that this mechanism protects Salmonella Typhimurium and Escherichia coli by increasing the copy number of the GyrI-like transcription regulator STM3175 (YgiV) which binds albicidin. X-ray crystallography and molecular docking studies reveal a conserved binding motif that can interact with aromatic building blocks of albicidin. Phylogenetic studies suggest that this resistance mechanism is ubiquitous in Gram-negative bacteria and our experiments confirm that STM3175 homologs can convey resistance in pathogens such as Vibrio vulnificus and Pseudomonas aeruginosa.

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Antimicrobial peptides (AMPs) possess bactericidal activity against a variety of pathogens depending on an overall balance of positively charged and hydrophobic residues. Selective fluorination of peptides serves to fine‐tune the intrinsic hydrophobicity and that could improve AMP bioactivity without affecting the sequence length. Only a few studies have focused on the impact of this unique element on antimicrobial potency and came to somewhat contractionary results. Moreover, the influence of fluorinated amino acids on peptide proteolysis is yet not fully understood. In this work, we tackle the link between side chain fluorination and both antimicrobial activity and proteolytic stability for two series of amphiphilic β‐hairpin peptides. In particular, a synergy between antimicrobial activity and peptide hydrophobicity was determined. All peptides were found to be barely hemolytic and non‐toxic. Most surprisingly, the fluorinated peptides were susceptible to enzymatic degradation. Hence, the distinctive properties of these polyfluorinated AMPs will serve for the future design of peptide‐based drugs.

Here, we report the draft genome sequences of Lactiplantibacillus plantarum strains DSMZ 8862 and DSMZ 8866, which are currently being used as authorized feed additives in the European Union under regulation (EC) number 1831/2003. The draft genome sequences contain 3,334 kbp (DSMZ 8862) and 2,992 kbp (DSMZ 8866) in 15 and 8 contigs, respectively.