Sequential cocultivation strategy for producing nisin-enriched foaming bacterial cellulose with enhanced antibacterial and functional properties

Bacteria cellulose (BC) is a natural biopolymer synthesized by Komagataeibacter xylinus (K. xylinus). To further enhance its functional properties, a foaming bacterial cellulose (FBC) with improved porosity and reswelling capacity was previously developed. In this study, an antimicrobial functionality was introduced to FBC by co-culturing K. xylinus with Lactococcus lactis, a nisin-producing lactic acid bacterium. The result demonstrated that the nisin titer was increased to 1.43-fold (from 3631.60 IU/mL⁻¹ to 5427.39 IU/mL⁻¹) utilizing 1:1 co-cultural ratio. Subsequently, most of the nisin-associated genes were upregulated during co-culture fermentation, nisA with 5.54-fold as the highest increasement. Furthermore, the others material properties: Fourier-transform infrared spectroscopy and thermogravimetric analysis, as well as the antibacterial zones around the nisin/FBC composites against Staphylococcus aureus indicates the successful nisin incorporation into FBC. Lastly, the nisin/FBC maintained the superior reswelling rates and non-toxicity properties of FBC. With this integrated strategy, the potential approach was established for upscaling nisin production, introducing an antimicrobial substance into the FBC, and uncovering the other applications of FBC.