Antimicrobial properties of amylose-fatty ammonium salt inclusion complexes

•Novel use of amylose inclusion complex to control pathogenic microbes.•Control of fungi, gram(+) bacteria and algae – some control of gram(-) bacteria.•Amylose complexes formed from inexpensive corn starch and fatty ammonium salts.•Process used to produce complex is inexpensive and globally utilized.•Complexes contain no new chemical bonds and do not lyse blood cells. Amylose-fatty (C12-C16) ammonium salt inclusion complexes are effective antimicrobial polymers causing growth inhibition of microbes at concentrations as low as 40 μg/mL of the complex (2 μg/mL active cationic ligand). The complex was more effective at controlling microbes than the uncomplexed ligand. The complexes were found to be particularly effective at inhibiting the growth of fungi, yeast, gram (+) bacteria, and algae; its performance was affected by pH. The complexes were not hemolytic at concentrations up to 2000 μg/mL. These agents were determined to be surface active polymers and their antimicrobial mode of action may involve cell membrane thinning or disruption, causing moderate leakage. Increased ligand concentration provided increased antimicrobial activity. Solutions of amylose complexes were found to be stable, retaining their antimicrobial efficacy after autoclaving, or after storage at room temperature for 6 months. Antimicrobial amylose complexes were produced using readily available inexpensive materials via an easily scalable process.