Effects of CMC addition on bacterial cellulose production in a biofilm reactor and its paper sheets analysis

Bacterial cellulose (BC) can be grown into any desired shape such as pellicles, pellets and spherelike balls, depending on the cultivation method, additives and cell density. In this study, different concentrations of carboxylmethylcellulose (CMC) in the production medium were evaluated for BC production by using a PCS biofilm reactor. The results demonstrated that BC production was enhanced to its maximum (∼13 g/L) when 1.5% of CMC was applied, which was 1.7-fold higher than the result obtained from control culture. The major type of the produced BC was also changed. The ratio of BC pellets of the total produced BC increased from 0 to 93% (w/w). Fourier transform infrared (FTIR) spectroscopy demonstrated that CMC was incorporated into BC during fermentation, and resulted in the decreased crystallinity and crystal size. The X-ray diffraction (XRD) patterns indicated that CMC-BC exhibited both lower crystallinity (80%) and crystal size (4.2 nm) when compared with control samples. The harvested BC was subjected to paper formation and its mechanical strength was determined. Dynamic mechanical analysis (DMA) results demonstrated that BC paper sheets exhibited higher tensile strength and Young's modulus when compared with regular paper.