Enhancing Bacterial Cellulose Yield and Quality Through Controlled Stress Conditions in <i>Komagataeibacter xylinus</i> Fermentation

ABSTRACT Bacterial cellulose has many unique and desirable properties, such as high crystallinity, high mechanical strength, a high degree of polymerization, high water holding capacity, flexibility, elevated purity, moldability in different shapes, and a unique nanostructure. Therefore, bacterial cellulose has a wide range of applications in the food industry, electronics, and biomedical fields. In this study, two different types of stress conditions, cold shock, and sonication, were applied during bacterial cellulose production. Bacterial growth, cellulose production, and structural and characteristic properties of produced bacterial cellulose were investigated in order to determine the effects of stress conditions on produced bacterial cellulose and the production profile of Komagataeibacter xylinus . Gene expression of bacteria that were stressed was also investigated for selected genes that are related to cellulose production in K. xylinus in order to understand the effect of stress conditions on gene expression. Both sonication and cold shock stress conditions have similar effects on both cell behaviors, such as promoting bacterial cellulose production instead of growth and differences in produced bacterial cellulose characteristics. For bacterial cellulose, the sonication 60‐s stress applied group yielded 1.3‐fold greater than the control group, and the cold shock stress applied group yielded 1.6‐fold greater than the control group. The application of both cold shock and sonication stress resulted in the production of stronger and more durable bacterial celluloses due to the random accumulation of cellulose fibers and the presence of more hydrogen bonds among cellulose fibers. Also, applied stress resulted in a rougher surface structure, higher tensile strength, a more thermostable structure, preserved molecular structure, and conformation of bacterial celluloses, along with a stronger structure.