Antimicrobial activity of copper‐humate‐cellulose sheets

Abstract

During our research, cellulose‐based test sheets containing copper and potassium humate were prepared and tested against several bacterial and fungal strains. The energy dispersive X‐ray spectrometry and attenuated total reflectance (ATR) Fourier‐transform infrared spectroscopy revealed that humate contributed to increase the copper content of the test sheets. The antimicrobial impact of test sheets on various fungi (Penicillium expansum, Wallemia sebi, and Aspergillus brasiliensis) and bacteria (genera Micrococcus, Enterococcus, Bacillus, Salmonella, Staphylococcus, Listeria genera) was tested using a modified agar diffusion‐based assay. On the basis of the disc diffusion results, the sheets effectively inhibited all the tested fungi and Gram‐positive bacteria. The highest antimicrobial effect was exhibited by the copper‐containing test sheet with 1:0.1 and 1:0.25 cellulose:humate weight ratio. Deterioration test with blackberries demonstrated the shelf life extending effect of the sheets.