Synergistic antimicrobial properties of active molecular chitosan with EDTA-divalent metal ion compounds.

The aim of this study was to elucidate the synergistic antimicrobial activity of chitosan hydrolysates derived from hydrolysis of high molecular weight chitosan (HMWC) with various kinds of divalent metal ions-EDTA compounds against Penicillium italicum. Amongst hydrolysates, active molecular chitosan (AMC) ranging of molecular weight approximately from 0.8 to 3.0 kDa has been newly researched and demonstrated that it has great antimicrobial activity. Copper, manganese, magnesium, cobalt and zinc ions were used to manufacture chelates with EDTA using a microwave apparatus. Inhibitory effect of AMC or chelates on growth of P. italicum was investigated for up to 72 hr. As the results, AMC showed the highest growth inhibitory activity in the presence of Zn-EDTA compound compared to the other ion chelates. According to these results, we demonstrated that although Zn-EDTA-chelating ligand alone does seem to have a little antimicrobial activity against P. italicum, however, it has synergistic effect against the fungal species when it combined with AMC. Taken together, we suggest that AMC-EDTA-Zinc combination (AEM-Zn) can be a great candidate as natural pesticide for defending postharvest decay of citrus fruits by the fungi. [ABSTRACT FROM AUTHOR]