Development of Antimicrobial Thermoplastic Material from Archaeal Poly-γ-L-Glutamate and Its Nanofabrication

摘要

Here we describe a stoichiometric ion-complex of archaeal poly-γ-L-glutamate (l-PGA) and hexadecylpyridinium cation (HDP~+), called PGAIC, which shows remarkable chemical resistance and potential as a novel functional thermoplastic. PGAIC films suppressed the proliferation of prokaryotic (Escherichia coli, Bacillus subtilis, Salmonella typhimurium, and Staphylococcus aureus) and eukaryotic (Sac-charomyces cerevisiae) microorganisms. Moreover, its antifungal activity was demonstrated against a prevalent species of Candida (Candida albicans) and a filamentous fungus (Aspergillus niger). The minimal inhibitory concentrations were estimated as 0.25 mg mL~(-1), and zones of growth inhibition appeared when PGAIC-coated polyethylene terephthalate (PET) films were placed in culture plates, whereas PET had very little effect on fungal growth. Soluble PGAIC thus shows promises as an antimicrobial and as a coating substrate. We also succeeded in synthesizing an L-PGA-based nanofiber using an ethanol solution of PGAIC.