Bacterial cellulose production from cotton-based waste textiles: Enzymatic saccharification enhanced by ionic liquid pretreatment

Cotton-based waste textiles were explored as alternative feedstock for production of bacterial cellulose (BC) by Gluconacetobacter xylinus. The cellulosic fabrics were treated with the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). [AMIM]Cl caused 25% inactivation of cellulase activity at a concentration as low as of 0.02 g/mL and decreased BC production during fermentation when present in concentrations higher than 0.0005 g/mL. Therefore, removal of residual IL by washing with hot water was highly beneficial to enzymatic saccharification as well as BC production. IL-treated fabrics exhibited a 5–7-fold higher enzymatic hydrolysis rate and gave a seven times larger yield of fermentable sugars than untreated fabrics. BC from cotton cloth hydrolysate was obtained at an yield of 10.8 g/L which was 83% higher than that from the culture grown on glucose-based medium. The BC from G. xylinus grown on IL-treated fabric hydrolysate had a 79% higher tensile strength than BC from glucose-based culture medium which suggests that waste cotton pretreated with [AMIM]Cl has potential to serve as a high-quality carbon source for BC production.