Production of bacterial nanocellulose and enzyme from [AMIM]Cl‐pretreated waste cotton fabrics: effects of dyes on enzymatic saccharification and nanocellulose production

BACKGROUND: Dyed used cotton textiles is a waste material associated with environmental problems. In this study, waste dyed cotton fabrics were used as feedstock for production of bacterial nanocellulose (BNC) with Gluconacetobacter xylinus and production of enzymes with Trichoderma reesei via enzymatic saccharification. RESULTS: Reactive dyes caused almost no inhibition of the cellulase activity at a concentration of 5 g L⁻¹, but decreased the BNC production at concentrations higher than 1 g L⁻¹. The BNC yield reached 12.8 g L⁻¹ with cotton hydrolysate, which was 48% higher than with glucose‐based medium. The spent fermentation broth after BNC harvest was subsequently utilized for enzyme production. Cellulase activities produced by T. reesei reached 5.3 U mL⁻¹ with spent detoxified purple bed sheet (PBS) hydrolysate, and 8.2 U mL⁻¹ with 2‐fold diluted spent PBS hydrolysate, which was almost the same or higher than with glucose medium (5.6 U mL⁻¹). The xylanase activities (60.2 U mL⁻¹ and 88.0 U mL⁻¹) obtained with the two media were 3–4 times higher than that obtained with glucose medium (21.0 U mL⁻¹). CONCLUSION: This approach could contribute to economical conversion of cellulosic waste to two high value‐added microbial products, while also providing new raw materials for a more sustainable textile industry. © 2015 Society of Chemical Industry