A study on the Influence of Surface area-to-Volume (S/V) Ratio on Production of Bacteria Cellulose in a Static-Batch Fermenter

The surface area-to-volume (S/V) ratio refers to the area of the air–liquid interface per unit volume of culture medium under static conditions. Optimizing the S/V ratio can reduce media consumption. However, past studies have provided limited data on its influence on bacterial cellulose (BC) fermentation. Therefore, this study investigates a broader and previously unexplored S/V ratio range (0.09 cm⁻¹ to 3.69 cm⁻¹) in static-batch fermentation using Komagataeibacter xylinus [formerly Acetobacter xylinum] 0416. A 7-day fermentation was conducted in vertical cylindrical glass fermenters, with different S/V ratios achieved by adjusting the volume of Hestrin–Schramm (HS) medium. BC dry mass and yield increased with the S/V ratio up to 2.46 cm⁻¹, but no further improvement thereafter. A significant decrease in media pH was observed when high BC production occurred. Higher tensile stress and strain were observed between S/V ratios of 0.50 cm⁻¹ and 1.50 cm⁻¹, indicating improved mechanical strength of BC. The optimal S/V ratio of 1.48 cm⁻¹ produced the highest BC dry mass (73 ± 4 mg) and a high yield (1.46 ± 0.09 g/L). The highest tensile stress (100 ± 70 MPa), tensile strain (3.2 ± 1.4 %), and water holding capacity (WHC; 18 ± 4 g/g) were observed at S/V ratios of 1.23, 1.48, and 0.09 cm⁻¹, respectively. Since the S/V ratio significantly influences BC yield and properties, it should be considered in static-batch fermentations to achieve a higher productivity and comply with the material requirements in scaled-up productions and industrial applications.