Synthesis, characterization and antimicrobial performance of novel nanostructured biopolymer film based on levan/clay/LL-37 antimicrobial peptide

The biopolymer of levan was produced with a density of 42.6 g/L by Pseudomonas mandelii in an optimized medium. The produced levan was characterized using FTIR, 1H NMR, and 13C NMR spectroscopy techniques and Zetasizer. More robust films were obtained with glycerol used as plasticizer in levan/sodium bentonite clay films. Film samples were evaluated in terms of water vapor permeability and GLG6 composition (5 g levan + 1 mL glycerol + 2 g Sodium bentonite clay + 50 mL 1% acetic acid) was found to be the most suitable film sample. The film sample was characterized by SEM, AFM, TGA analyses. Different amounts of LL-37 antimicrobial peptide were added to the film samples and antimicrobial properties were examined on different microorganisms. The human cathelicidin LL-37 led to synergistic antimicrobial effects with levan against pathogen microorganisms. The highest antimicrobial effect was observed with an inhibiton zone diameter of 19,5 mm measured on GLG6 film composition with 500 μL of LL-37 antimicrobial peptide on E.coli.