Project description:Biogenic amine-producing bacteria are responsible for the production of basic nitrogenous compounds, such as histamine, cadaverine, tyramine and putrescine, after foods spoil due to microorganisms. In the present work, we applied a shotgun proteomics approach to quickly and easily characterize 15 different foodborne strains of biogenic amine-producing bacteria. A total of 10673 peptide spectrum matches (PSMs) belonging to 4081 nonredundant peptides and corresponding to 1811 annotated proteins were identified. With the results, relevant functional pathways were determined and the strains were differentiated into different Euclidean hierarchical clusters. Moreover, a predicted protein‒protein interaction network of biogenic amine foodborne strains was created. The whole confidence network contains 260 nodes and 1973 interactions. Most of the identified proteins were related to pathways and networks of energy, putrescine metabolism and host‒virus interaction. In addition, a total of 556 nonredundant peptides were identified as virulence factors, and most of these peptides corresponded to functions such as toxins, antimicrobial compound production, antimicrobial resistance, additional resistances and tolerances, host colonization and immune evasion, ABC transporters, phage proteins, and alternative virulence factors and proteins involved in horizontal transfer. Potential species-specific peptide biomarkers were screened. Thus, 77 species-specific peptide biomarkers belonging to 64 different proteins were proposed to identify 10 species (Enterobacter aerogenes, Enterobacter cloacae, Hafnia alvei, Klebsiella oxytoca, Morganella morganii, Proteus mirabilis, Proteus penneri, Proteus vulgaris, Raoutella planticola, Stenotrophomonas maltophilia). All of these results constitute the first major dataset of peptides and proteins of seafood biogenic amine-producing strains. This repository may be useful for further studies, for the development of new therapeutic treatments for food intoxication and for tracking microbial sources in foodstuffs.

Project description:The spread of antimicrobial resistance (AMR), coupled with the decline in antibiotic development, has become a major public health concern. Recent studies estimate that around 700,000 people die each year from infections caused by multidrug-resistant (MDR) bacteria. This led the WHO to publish the ESKAPEE list of high priority pathogens for AMR, namely Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli. Among these, Gram-negative bacteria (K. pneumoniae, A. baumannii, P. aeruginosa, Enterobacter spp., and E. coli) are particularly overrepresented. This is mainly due to their high propensity to develop multiple resistance mechanisms, in addition to their intrinsic resistance to many antimicrobials, which is due to their membrane composition and the expression of broad-spectrum efflux pumps. One strategy to combat such AMR is the use of drug enhancers that are able to restore the antibacterial activity of poorly active antibiotics. In this context, we demonstrated that the polyamino-isoprenyl enhancer, NV716, efficiently potentiates the antibacterial activity of two families of multi-target Ser/Cys-based enzyme inhibitors, namely the oxadiazolone derivatives (OX) and the Cyclipostins and Cyclophostin analogs (CyC), against Enterobacter cloacae, while remaining inactive against other Gram-negative bacteria. We confirmed that NV716 potentiates some OX & CyC compounds by permeabilizing the outer membrane and thus by increasing the inhibitor accumulation as shown by fluorescence confocal microscopy. By using bio-orthogonal click-chemistry activity-based protein profiling (CC-ABPP) approach coupled to proteomic analysis, we also identified the target proteins of the best OX & CyC inhibitors from E. cloacae lysate, thereby confirming their multi-target nature. Interestingly, 6 of the latter proteins were also captured via CC-ABPP in P. aeruginosa lysate, and are highly conserved in all Gram-negative bacteria. These results provide proof of concept that both OX & CyC, if successfully potentiated, could be used against a wide range of ESKAPEE Gram-negative bacteria.

Project description:Antimicrobial peptides (AMPs) represent promising alternatives to conventional antibiotics in the fight against multidrug-resistant pathogens. Here, we characterize the antibacterial properties and molecular mode of action of the C-terminal fragment of the Medicago truncatula nodule-specific cysteine-rich peptide NCR169 (NCR169C17-38). This peptide exhibits strong bactericidal activity against a broad panel of Gram-positive and Gram-negative pathogens, including members of the ESKAPE group (Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli). NCR169C17-38 acted rapidly by permeabilizing bacterial membranes and causing severe morphological damage, outperforming polymyxin B in the rate of membrane disruption. The peptide bound selectively to anionic bacterial lipids such as cardiolipin and displayed remarkable thermal and storage stability. Moreover, NCR169C17-38 effectively inhibited biofilm formation and eradicated pre-formed biofilms of Acinetobacter baumannii even at sub-MBC concentration (3.2 M), a feature not observed for polymyxin B. Transcriptomic analysis of Escherichia coli exposed to sublethal peptide doses revealed a global shutdown of bacterial metabolic and genetic functions, with 450 of 503 differentially expressed genes being downregulated. Strong repression of genes involved in translation, energy production, and cell envelope biosynthesis was accompanied by upregulation of stress- and rescue-related genes linked to membrane repair, ion transport, and oxidative stress responses. Together, these results demonstrate that NCR169C17-38 exerts multifaceted antimicrobial effects - disrupting membranes, binding nucleic acids, and inducing transcriptional collapse - while maintaining its stability and biocompatibility. Together with its previously established antifungal activity and lack of mammalian cytotoxicity, NCR169C17-38 represents a compelling candidate for development as a next-generation antimicrobial agent.

			Action	DRS
	137.SUB12904_MetabolomicsData 2.xlsx	Xlsx
	SUB12502p3_0_5MIC_1.raw	Raw
	SUB12502p3_0_5MIC_2.raw	Raw
	SUB12502p3_0_5MIC_3.raw	Raw
	SUB12502p3_1_0MIC_1.raw	Raw

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Small molecule produced by Photorhabdus interferes with ubiquinone biosynthesis in Gram-negative bacteria

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