Production of High-Value-Added Bacterial Nanocellulose with Thinner Fiber Using Novel Yarrowia lipolytica Extract from Erythritol Industry Waste

The rapid growth of the erythritol fermentation industry has prompted interest in the efficient utilization of its yeast cell residue. This study concentrates on extracting nitrogen sources from Yarrowia lipolytica waste to enhance microbial fermentation of bacterial nanocellulose (BNC), a valuable nanoscale biopolymer. Various treatments, including enzymatic, mechanical, and alkali treatments at different temperatures, were employed to improve extraction. The most effective treatments were alkali treatments at 50 and 90 °C, followed by lyticase and protease treatments. The highest production of soluble protein/amino acid contents reached 1.997 ± 0.018 and 2.328 ± 0.018 g/L, respectively. The 50 °C treatment was the most cost-effective based on thermal energy calculations and was selected for further analysis. Y. lipolytica yeast extract enhanced BNC production to 4.017 g/L, a 66.5% improvement over the commercial Saccharomyces cerevisiae yeast extract. Substituting half of the commercial yeast extract with the Y. lipolytica extract also increased BNC production by 22.6%. No significant differences were observed in the chemical composition, crystallinity, and thermal stabilities of BNC prepared from Y. lipolytica extract compared to those of commercial yeast extract. Transmission electron microscopy (TEM) revealed thinner fiber diameters in BNC prepared from Y. lipolytica extract, and atomic force microscopy (AFM) measurements showed a remarkable 189.1% increase in surface roughness.