## 3 Results and Discussion
### BC Biosynthesis on Waste Media
On the other hand, the BC yield produced by _Ga. hansenii_ in the medium of AW reached approx. 0.5 g\(\cdot\)dm\({}^{-3}\), regardless of the concentration used. Most AAB exhibit a limited ability to absorb the lactose present in whey. This is caused by the lack or low activity of the \(\beta\)-galactosidase enzyme responsible for the hydrolysis of lactose to simple sugars [41]. Figure 2: Dry mass of bacterial cellulose obtained on waste media using _Ga. hansenii_ ATCC 23769. The same uppercase letters in the same concentration for different waste media are not statistically significantly different. The same lowercase letters in the same waste media for different concentration are not statistically significantly different. Thus, the biosynthesis of BC by AAB in whey may be impeded due to the lower availability of glucose, which is the basic structural unit of cellulose. Figure 4 shows the BC yield obtained after the cultivation of _K. xylinus_ in waste media. Statistical analysis showed that, as for the strain _Ga. hansenii_, when obtaining BC by _K. xylinus_, the type of waste was more important than its concentration. In the medium with banana peels with a concentration of 20 g\(\cdot\)dm\({}^{-3}\), the BC yield was about 1.4 g\(\cdot\)dm\({}^{-3}\). In the same medium, but with a concentration of 50 g\(\cdot\)dm\({}^{-3}\) and 70 g\(\cdot\)dm\({}^{-3}\), the yield of BC was 2.1 g\(\cdot\)dm\({}^{-3}\). After culturing _K. xylinus_ in the media of celery pomace, 1.4 g\(\cdot\)dm\({}^{-3}\) (waste concentration of 20 g\(\cdot\)dm \({}^{-3}\)) and 0.3 g\(\cdot\)dm\({}^{-3}\) (waste concentration of 50 g\(\cdot\)dm\({}^{-3}\)) BC were obtained, respectively. It is worth mentioning that this is a surprising result because, as in the case of _Ga. hansenii_, the most BC was obtained at the lowest waste concentration (20 g\(\cdot\)dm\({}^{-3}\)). This could have been due to the high content of phenolic compounds present in celery. As reported by [PERSON] et al. and [PERSON] [42; 43], luteolin, coumaric acid, and ferulic acid present in celery had an inhibitory effect on the growth of acetic bacteria. In media with 50 g\(\cdot\)dm\({}^{-3}\) and 70 g\(\cdot\)dm\({}^{-3}\) celery, the content of phenolic compounds was high enough to inhibit the growth of _Ga. hansenii_  
Figure 4: Dry mass of bacterial cellulose obtained on waste media using _K. xylinus_ K2G30. The same uppercase letters at the same concentration for different waste media are not statistically significantly different. The same lowercase letters at the same waste media for different concentrations are not statistically significantly different. Figure 3: Bacterial cellulose obtained by _Ga. hansenii_ ATCC 23769 and _K. xylinus_ K2G30 on waste media: banana peels, celery pomace, fish waste, hemp pomace, and acid whey. and _K. xylimus_, which prevented the production of BC. For fish waste, the highest BC yield (1.85 g\(\cdot\)dm\({}^{-3}\)) was obtained in the medium with a concentration of 50 g\(\cdot\)dm\({}^{-3}\). This may indicate that 5% of fish waste was best suited for BC biosynthesis. The fish waste medium with a concentration of 20 g\(\cdot\)dm\({}^{-3}\) was probably too poor in nutrients to ensure high efficiency of BC biosynthesis, and thus significantly less biopolymer was obtained (0.3 g\(\cdot\)dm\({}^{-3}\)). In turn, in the fish waste medium with a concentration of 70 g\(\cdot\)dm\({}^{-3}\)_K. xylimus_ produced 1.5 g\(\cdot\)dm\({}^{-3}\) BC, which could have been caused by too high a concentration and inhibitory effect of some components of fish waste on the biosynthesis of BC. As reported by [PERSON] et al. [44], a negative impact of peptide hydrolyses from fish waste on the growth of some of the Gram-negative bacteria was demonstrated [44]. However, it should be noted that _K. xylimus_ demonstrated a better ability to produce BC from fish waste compared with _Ga. hansenii_. This may indicate that _K. xylimus_ is better adapted to BC biosynthesis under unfavourable conditions than _Ga. hansenii_.