## 3 Results and Discussion
### Moisture Content and Swelling Ratios  
The moisture content ratio of BC pellicles is the most crucial parameter concerning their further application in medicine or cosmetology. It can be modified by many factors, such as the properties of the cultivation media and the potential of the used _K. xylinus_ strain [41]. The appropriate moisture content of dressing materials strongly determines the wound-healing process's success and inhibits infectious organisms' colonisation [42]. Depending on the cultivation medium variant, the final mass of BC without water (which corresponds to the mass of the cellulose fibres only) amounted to less than 2% of the initial wet BC weight that resulted in obtaining the MCR on a 98% level or higher (Table 3). The values were consistent with the other earlier reports for BC produced in various fermentation systems [43; 44]. The second water-related tested parameter of BC was the swelling ratio, which is also an essential property of this biopolymer. The value of this factor strongly depends on  
Figure 5: The SEM images of the BC obtained from cultures with different oligo- and polysaccharides as carbon source hydrolysed by specific enzymes at 20,000\(\times\) (left column), 100,000\(\times\) (centre column) magnification and distribution of BC microfibrils diameters’ (right column). The BC samples obtained from standard HS medium—(**a–c**), medium with sucrose and \(\beta\)-D-Fru—(**d–f**), medium with lactose and \(\beta\)-Gal—(**g–i**), and from a medium with starch and GLA—(**j–l**). The presented SEM images show the BC surface obtained from modified cultivation media with the highest enzymes units amounts. the pH and ionic strength of the solvent. The swelling occurs due to increased distance between the chains in the polymer structure, which induces the release or absorption of water molecules or any other solution in which the BC was wetted [45]. The obtained BC, regardless of the medium variant used for their _K. xylinus_ cultivation, exhibited a similar speed of maximum water uptake, regardless of the solution's pH, achieved after an hour of incubation, without significant changes after a further 24 h (Figure 6). Nevertheless, the BC from cultures with enzymes combined with oligo- and polysaccharide exhibited the highest SR at pH 5.0 (Figure 6b,e,h). In comparison, the BC from standard HS media showed the best SR at pH 7.0 (Figure 6c,f,i). High water retention is one of the most important and unique advantages of BC and its applications. It is worth noting that rehydration of once-dried BC does not allow obtaining such a high degree of biopolymer hydration, and the water content is about a few percent of the initial wet polymer mass and depends on the ionic strength of the solvent and the humidity condition of the experimental environment [46; 47]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multirow{2}{*}{**Initial Amount of Enzyme in Medium (U/mL)**} & \multicolumn{2}{c}{**XRD**} & \multicolumn{2}{c}{**ATR-FTIR**} \\ \hline  & & **CrI (\%)** & **Crystallites Size (nm)** & **LOI** & **TCI** \\ \hline Control & — & 93.6 & 5.9 & 1.75 \(\pm\) * 0.095 & 1.46 \(\pm\) 0.10 \\ \hline  & 1.6 & 95.1 & 5.9 & 2.04 \(\pm\) 0.64 & 1.49 \(\pm\) 0.31 \\ \(\beta\)-D-Fru & 3.2 & 92.4 & 5.4 & 1.80 \(\pm\) 0.38 & 1.46 \(\pm\) 0.18 \\  & 4.8 & 90.1 & 5.6 & 1.89 \(\pm\) 0.51 & 1.37 \(\pm\) 0.07 \\  & 6.2 & 91.8 & 5.6 & 1.79 \(\pm\) 0.37 & 1.33 \(\pm\) 0.15 \\ \hline  & 3.0 & 91.6 & 5.6 & 2.17 \(\pm\) 0.42 & 1.53 \(\pm\) 0.23 \\ \(\beta\)-Gal & 6.0 & 91.6 & 5.6 & 2.17 \(\pm\) 0.48 & 1.74 \(\pm\) 0.14 \\  & 12 & 94.1 & 5.5 & 2.12 \(\pm\) 0.40 & 1.63 \(\pm\) 0.14 \\  & 60 & 94.2 & 5.8 & 2.06\(\pm\) 0.34 & 2.23 \(\pm\) 0.19 \\ \hline  & 5.0 & 93.9 & 5.9 & 1.59 \(\pm\) 0.26 & 1.23 \(\pm\) 0.12 \\ GLA & 10 & 90.9 & 5.7 & 1.69 \(\pm\) 0.23 & 1.35 \(\pm\) 0.12 \\  & 20 & 91.8 & 5.6 & 1.80 \(\pm\) 0.19 & 1.39 \(\pm\) 0.08 \\  & 40 & 91.2 & 5.5 & 1.62 \(\pm\) 0.35 & 1.44 \(\pm\) 0.12 \\ \hline \hline \end{tabular}  
* \(\pm\)—standard deviation.  
\end{table}