Bacterial nanocellulose membranes combined with nisin: a strategy to prevent microbial growth

Consumer concerns about synthetic additives is increasing and it can be interesting to apply natural antioxidants with antimicrobial properties. Developing a packing material composed by a natural polymer, such as bacterial nanocellulose membrane (BNCm) loaded with nisin may be applied as a method to keep food quality and to inhibit growth of microbial contaminants. For this reason, the aim of this study was to evaluate antimicrobial activity of BNCm loaded with nisin. Antimicrobial activity of nisin, utilizing or not EDTA solution,was assessed by minimal inhibitory concentration and agar diffusion assay, utilizing Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Antioxidant activity and physico-chemical properties were also evaluated. For the MIC evaluation, the combination of nisin solution with EDTA showed a synergistic effect. Concerning E. coli nisin with EDTA 20-40mM, MIC was 31.25g/mL. Concerning P. aeruginosa nisin with EDTA 10-20mM, MIC was 125g/mL. Concerning S. aureus nisin with EDTA 10mM, MIC was 15.63g/mL, two times lower than without EDTA. The BNCm antimicrobial activity for E. coli, by agar diffusion assay, was observed when nisin was loaded at 250 or 500g/mL with EDTA 10 or 20mM. However, for S. aureus, the antimicrobial activity was observed for BNCm loaded with nisin 15g/mL with 10mM EDTA. For P. aeruginosa, antimicrobial activity was not observed. Nisin exhibited significant antimicrobial and antioxidant activity. The results provide evidence that BNCm loaded with nisin is a promising control strategy to prevent microorganism contamination.