Physical and antibacterial properties of bacterial cellulose films supplemented with cell-free supernatant enterocin-producing Enterococcus faecium TJUQ1

In this study, a composite film was prepared with bacterial cellulose (BC) of Gluconacetobacter xylinus and cellfree supernatant (CFS) of Enterococcus faecium TJUQ1, which was named BC-E. The optimum conditions for the preparation of the composite film with a minimal antibacterial activity were the soak of BC in 80 AU/mL CFS for 6 h. By scanning electron microscope observation, the surface network structure of BC-E was denser than that of BC. The tensile strength of BC and BC-E was 4.65 +/- 0.88 MPa and 16.30 +/- 0.92 MPa, the elongation at break of BC and BC-E was 3.33 +/- 0.89% and 31.60 +/- 1.15%, respectively, indicating the mechanical properties of BC-E were significantly higher than that of BC (P < 0.05). The swelling ratio of BC-E (456.67 +/- 7.20%) was lower than that of BC (1377.78 +/- 9.07%), demonstrating BC-E films presented better water resistance. BC-E films were soaked with 320 AU/mL CFS, and then used to pack the ground meat with 6.55 log10 CFU/g of Listeria monocytogenes. After 8 days of storage, the number of bacteria decreased by 3.16 log10 CFU/g. Similarly, total mesophilic bacterial levels in the ground meat decreased by 2.41 log10 CFU/g compared to control groups.

Automated summary

A composite film named BC-E was prepared using bacterial cellulose (BC) of Gluconacetobacter xylinus and cellfree supernatant (CFS) of Enterococcus faecium TJUQ1, showing significantly improved mechanical properties compared to BC. The BC-E film exhibited higher tensile strength, elongation at break, and water resistance than BC, and effectively reduced the number of Listeria monocytogenes and total mesophilic bacteria in ground meat during storage.