Optimization of bacterial nanocellulose synthesis using surfactants for immobilization of Saccharomyces cerevisiae to enhance resistance to lignocellulose-derived inhibitor.

Optimization of bacterial nanocellulose (BNC) synthesis using surfactants for immobilization of Saccharomyces cerevisiae to enhance resistance to lignocellulose-derived inhibitors is critical for improving bioethanol production efficiency. Lignocellulosic hydrolysates often contain inhibitors such as ferulic acid, which significantly reduce yeast fermentation activity. BNC, with its unique three-dimensional network structure, is a promising carrier for yeast immobilization. However, its dense structure limits yeast cell attachment and nutrient transfer. In this study, rhamnolipids (RHA), an anionic biosurfactant, were introduced into the Hestrin-Schramm (HS) medium. Adding 4 g/L RHA increased the specific surface area of BNC from 26.55 to 37.59 m2/g, the porosity from 45.34 ± 6.65 % to 55.34 ± 2.10 %, the water holding capacity from 179.00 ± 9.03 g/g to 208.19 ± 3.20 g/g and decreased the crystallinity of BNC from 95.04 % to 60.27 %. Under 5 mM ferulic acid, the immobilized yeast exhibited enhanced glucose utilization and began ethanol metabolism earlier. This study presents an environmentally friendly immobilization method and holds significant potential for batch fermentation under inhibitory conditions.