EFFECTS OF CULTIVATION PARAMETERS ON BACTERIAL NANOCELLULOSE PRODUCTION BY KOMAGATAEIBACTER XYLINUS DSM 2325

Abstract

Bacterial nanocellulose (BNC) is a high-value biopolymer with promising applications in biomedical engineering, food technology, packaging, and advanced materials. However, industrial implementation remains constrained by relatively low production yields and the sensitivity of cellulose biosynthesis to cultivation conditions. In the present study, the combined effects of temperature, initial pH, ethanol concentration, and sodium lactate concentration on BNC production by Komagataeibacter xylinus (K. xylinus) DSM 2325 under agitated cultivation conditions were investigated using a four-factor Box–Behnken design coupled with Response Surface Methodology (RSM). Twenty-nine experimental runs were conducted, and BNC yield was evaluated as dry cellulose production. The highest experimental yield (0.446 g/L) was obtained at 30 °C, pH 6, 2% (v/v) ethanol, and without sodium lactate supplementation. Analysis of variance demonstrated that temperature, pH, and sodium lactate significantly affected BNC production, whereas ethanol showed no statistically significant linear effect. The developed quadratic model was significant (p = 0.0001) with an R² value of 0.7752. Numerical optimization predicted optimal cultivation conditions of 24.4 °C, pH 4.57, 2% ethanol, and 0.04% sodium lactate, corresponding to a predicted yield of 0.767 g/L. However, experimental validation revealed lower cellulose production under optimized conditions than under the standard medium. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the successful synthesis of chemically pure BNC with a characteristic cellulose I crystalline structure. Scanning electron microscopy (SEM) was used to evaluate the surface morphology and fibrillar network structure of the bacterial nanocellulose samples. These findings demonstrate the importance of experimental validation when applying statistical optimization approaches to BNC production systems. 

Keywords: bacterial nanocellulose; Komagataeibacter xylinus; response surface methodology; Box–Behnken design; ethanol; sodium lactate; optimization.