Bacterial Cellulose Production Enhancement in Repeated Static Batch Culture of Acetobacter xylinum in Bench-Scale

Bacterial Cellulose (BC) is commonly produced by a static batch culture, which is a time-consuming and low-yield process. Therefore, this study developed a new repeated static batch culture with optimal conditions to reduce production time, increase production value, and thus reduce BC production costs. First, by examining the volume of the surface ratio (depth) of the culture medium at 5 different levels and then the effect of cultivation time on the production efficiency of BC, at the desired depth of 1.6 cm, 5.6 g/L of BC per week was obtained. Then, for more production enhancement of BC, a new repeated static batch culture was developed at the obtained optimal conditions in the previous step. Then, by investigating the effect of the number of feed addition cycles in the repeated-batch culture, the maximum BC production of 13.06 g/L was obtained at the optimum cycle number 4 (7 days per cycle) with aeration. The highest amount of produced BC at the end of the 5th cycle was 41.15 g in a culture volume of 3.5 L at 6 cm depth. Aeration at the rate of 0.1vvm increased BC production in all cycles and decreased overall production time. The highest BC concentration was 13.27 g/L at the end of the third cycle, and the maximum production was 44.2 g at the end of the 4th cycle. A comparison of shear stress and Young's modulus of BC sheets produced in different cycles of the repeated-batch static culture with and without aeration showed that increasing the number of cycles as opposed to aeration makes a significant difference in the mechanical properties of the produced BC sheets.