Farklı stres koşulları altında bakteriyel selüloz üretiminin moleküler seviyede incelenmesi

Bacterial cellulose has many unique, fascinating, and desirable properties such as high crystallinity, high mechanical strength, high degree of polymerization, high water holding capacity, flexibility, elevated purity, mouldability in different shapes and unique nanostructure. Therefore, bacterial cellulose has a wide range of applications in food industry, electronic and biomedical fields. In this study, two different types of stress conditions, which are cold shock and sonication, were applied during bacterial cellulose production. Structural and characteristic properties of produced bacterial cellulose and behavior of K. xylinus were investigated. Both sonication and cold shock stress conditions have similar effects on both cell behavior and differences in produced bacterial cellulose characteristics. For bacterial cellulose production, sonication 60 seconds stress applied group yielded 1.3 fold greater than control group with 2.9 g/L BC production and cold shock stress applied group yielded 1.6 fold greater than the control group with 3.3 g/L. The application of both cold shock and sonication stress, resulted in the production of stronger and more durable bacterial celluloses. 2.1 fold grater ultimate strength than the control group for sonication stress and 2.0 fold grater ultimate strength than the control group for cold shock stress. Applied stress resulted in a rougher surface structure, higher tensile strength, more thermostable structure with 1.73 fold less mass loss per temperature change than the control group for sonication stress, 1.8 fold less mass loss per temperature change than the control group for cold shock stress, and preserved molecular structure and conformation of bacterial celluloses along with stronger structure. For sonication stress, gene expression levels for bcsA, ccpAx genes were investigated. For 30 seconds, gene expression reached higher levels than the control group for bcsA gene as 1.4 fold of the control group on the 4th day and 1.7 fold of the control group on the 7th day. While ccAx gene is 0.8 fold of the control group on the 4th day, reached 1.4 fold on the 7th day of the fermentation. For 60 seconds, higher expression levels were reached when compared with 30 seconds on the first days. When compared to control group, 1.8 fold greater for bcsA gene and 2.4 fold greater for ccpAx gene on the 4th day. However continuous stress resulted in expression levels to drop 0.8 fold for bcsA gene and 0.6 fold for ccpAx gene when compared with the control group.