Bacterial cellulose-based living materials for wastewater treatment via a novel co-culture strategy

Biofilm-mediated wastewater treatment offers an eco-friendly bioremediation approach involving the use of immobilized on carriers to degrade pollutants. In this study, we present for the first time the use of bacterial cellulose (BC) integrated with viable Bacillus cells for biofilm-mediated wastewater treatment. Using a novel two-step culture method, the materials prepared in corn steep liquor (CSL) fermentation medium achieved a Bacillus spore embedding count of 5.34 ± 0.70 × 10⁵ CFU/g. After resuscitation in LB medium, viable Bacillus cells increased significantly to 5.35 ± 0.71 × 10⁸ CFU/g. These BC materials effectively removed 62.89 % of chemical oxygen demand (COD) from artificial wastewater and 96.67 % from kitchen wastewater (KWW). Furthermore, BC-based engineered living materials (ELMs) containing Bacillus cells with overexpressing catalase completely degraded 4 % hydrogen peroxide (H₂O₂) in wastewater within 10 min. Additionally, these materials have the characteristics of reusability and long-term storage, aligning with the green and sustainable development goals. Because Bacillus is an excellent host for heterologous expression, our novel two-step culture strategy for BC-based ELMs containing viable Bacillus cells can improve the efficiency of biofilm-mediated water treatment, and facilitate the development of specific ELMs tailored to diverse application contexts.