Rational design of Abhisin-like peptides enables generation of potent antimicrobial activity against pathogens.

Infections caused by pathogens can be a significant challenge in wound healing, particularly when antimicrobial resistance is a factor. This can pose a serious threat to human health and well-being. In this scenario, it is imperative to explore novel antimicrobial agents to fight against multi-drug resistant (MDR) pathogenic bacteria. This study employed rational design strategies, including truncation, amino acid replacement, and heterozygosity, to obtain seven α-helical, cationic, and engineered peptides based on the original template of Abhisin. Among the analogs of Abhisin, AB7 displayed broad-spectrum and potent antimicrobial activity, superior targeting of membranes and DNA, and the ability to disrupt biofilms and anti-endotoxins in vitro. Additionally, we evaluated the anti-infection ability of AB7 using a murine skin wound model infected with methicillin-resistant Staphylococcus aureus (MRSA) and found that AB7 displayed negligible toxicity both in vitro and in vivo. Furthermore, AB7 exhibited desirable therapeutic efficacy by reducing bacterial burden and pro-inflammatory mediators, modulating cytokines, promoting wound healing, and enhancing angiogenesis. These results highlight the potential of AB7 as a promising candidate for a new antibiotic. KEY POINTS: • A α-helical, cationic, and engineered peptide AB7 was obtained based on Abhisin. • AB7 exhibited potent antimicrobial activity and multiple bactericidal actions. • AB7 effectively treated infected skin wounds in mice.

The investigation on the characteristic metabolites of Lactobacillus plantarum RLL68 during fermentation of beverage from by-products of black tea manufacture.

At present, lactic acid bacteria (LAB) fermentation is commonly considered as an effective strategy to remarkably drive the improvement of flavor and nutritional value, and extend shelf-life of fermented foods. In this study, the by-product of tea manufacture, including broken tea segments and tea stalk, was used to produce fermented tea beverages. In addition, the residual components of matrices and bacterial metabolites were measured, as well as the sensory quality of the beverage was evaluated. Subsequently, the determination of monosaccharides, volatile aroma profile, free amino acids, biogenic amines and organic acids, and several functional substances involving γ-aminobutyric acid (GABA), polyphenols, caffeine and L-theanine were carried out. The results revealed that glucose, fructose, mannose and xylose are principal carbon source of Lactobacillus plantarum RLL68 during the fermentation; moreover, the abundance of aromatic substances is varied dramatically and the characteristic flavors of the beverages, particularly fermentation for 48 h and 72 h, are imparted with sweet and fruity odor on the basis of initial nutty and floral odor; Meanwhile, the organoleptic qualities of fermented beverages is also enhanced. Furthermore, the levels of organic acids and GABA are elevated, while the bitter amino acids, as well as some bioactive substances including tea polyphenols and L-theanine are declined; Besides, the caffeine level almost remains constant, and quite low levels of various biogenic amines are also observed. The results of this study will provide the theoretical basis to steer and control the flavor and quality of the fermented tea beverages in the future.

iTRAQ-BASED Proteomic Analysis of the Mechanism of Fructose on Improving Fengycin Biosynthesis in Bacillus Amyloliquefaciens.

Fengycin, as a lipopeptide produced by Bacillus subtilis, displays potent activity against filamentous fungi, including Aspergillus flavus and Soft-rot fungus, which exhibits a wide range of potential applications in food industries, agriculture, and medicine. To better clarify the regulatory mechanism of fructose on fengycin biosynthesis, the iTRAQ-based proteomic analysis was utilized to investigate the differentially expressed proteins of B. amyloliquefaciens fmb-60 cultivated in ML (without fructose) and MLF (with fructose) medium. The results indicated that a total of 811 proteins, including 248 proteins with differential expression levels (162 which were upregulated (fold > 2) and 86, which were downregulated (fold < 0.5) were detected, and most of the proteins are associated with cellular metabolism, biosynthesis, and biological regulation process. Moreover, the target genes' relative expression was conducted using quantitative real-time PCR to validate the proteomic analysis results. Based on the results of proteome analysis, the supposed pathways of fructose enhancing fengycin biosynthesis in B. amyloliquefaciens fmb-60 can be summarized as improvement of the metabolic process, including cellular amino acid and amide, fatty acid biosynthesis, peptide and protein, nucleotide and nucleobase-containing compound, drug/toxin, cofactor, and vitamin; reinforcement of peptide/protein translation, modification, biological process, and response to a stimulus. In conclusion, this study represents a comprehensive and systematic investigation of the fructose mechanism on improving fengycin biosynthesis in B. amyloliquefaciens, which will provide a road map to facilitate the potential application of fengycin or its homolog in defending against filamentous fungi.