Lactiplantibacillus plantarum MTCC 2621 is a well-characterized probiotic strain and is reported to possess many health benefits. However, the wound healing potential of this probiotic is yet to be explored. Here, we have assessed the antibacterial, antioxidant, and wound healing activities of cell-free supernatant of Lactiplantibacillus plantarum MTCC 2621 (Lp2621). Lp2621 exhibited excellent antibacterial activity against the indicator bacteria in the agar well diffusion assay. Lp2621 did not show any hemolytic activity. The safety of Lp2621 gel was established using the skin irritation assay in BALB/c mice, and no dermal reactions were observed. The supernatant showed 60–100% protection of A549 cells against H2O2-induced stress. In the scratch assay, Lp2621 accelerated wound healing after 24 h of treatment. The percent wound healing was significantly higher in cells treated with Lp2621 at 18–24 h posttreatment. In an excision wound healing in mice, topical application of Lp2621 gel showed faster healing than the vehicle- and betadine-treated groups. Similar wound healing activity was observed in wounds infected with Staphylococcus aureus. Histological examination revealed better wound healing in Lp2621-treated mice. Topical treatment of the wounds with Lp2621 gel resulted in the upregulation of pro-inflammatory cytokine IL-6 in the early phase of wound healing and enhanced IL-10 expression in the later phase. These findings unveil a protective role of Lp2621 against bacterial infection, oxidative stress, and wound healing.

The flexibility of the adenylation domains of non-ribosomal peptide synthetases (NRPSs) to different substrates creates a diversity of structurally similar peptides. In the present study, we investigated the antimicrobial activity of different natural variants synthesized by tridecaptin M gene cluster and performed the in vitro drug kinetics on this class. The natural variants were isolated and characterized using MALDI-MS and tandem mass spectrometry. All the peptides were studied for their antimicrobial activity in different pathogens, including colistin-resistant bacteria, and for haemolytic activity. Furthermore, in vitro drug kinetics was performed with tridecaptin M (or M1, the major product of the gene cluster). The natural variants displayed a varying degree of bioactivity with M11 showing the most potent antibacterial activity (MIC, 1–8 µg/ml), even against A. baumannii and P. aeruginosa strains. The in vitro kinetic studies revealed that tridecaptin M at a concentration of 16 µg/ml eradicated the bacteria completely in high-density culture. The compound demonstrated desirable post-antibiotic effect after two-hour exposure at MIC concentration. We also observed the reversal of resistance to this class of antibiotics in the presence of carbonyl cyanide m-chlorophenyl hydrazine (CCCP). Altogether, the study demonstrated that tridecaptins are an excellent drug candidate against drug-resistant Gram-negative bacteria. Future studies are required to design a superior tridecaptin by investigating the interactions of different natural variants with the target.

No abstract