Effect of the media composition on the BC yield, final pH and total substrate consumption
The effects of the media composition on the BC yield, final pH and substrate consumption of the fermentation media by Komagataeibacter sp. CCUG73629 and Komagataeibacter sp. CCUG73630 are shown in Tables 2 and 3. The BC yield and final pH of the media enriched with Komagataeibacter sp. CCUG73629 ranged from 100–283.3% and 3.7–4.2, respectively. The highest yield was recorded in M4, whereas the lowest BC yield was observed in M6. The highest pH was observed in M2, and the lowest was observed in M6. For Komagataeibacter sp. CCUG73630, the highest BC yield and final pH of the media ranged from 43.5–100.0% and 3.5–4.0, respectively. The highest yield was recorded in M6, whereas the lowest yield was recorded in M3. The highest pH was observed in M2, and the lowest was observed in M5. During BC production, the highest total substrate consumption of 81.5% was observed in M3 (glucose, mannose, xylose, galactose and arabinose) by Komagataeibacter sp. CCUG73629, whereas in Komagataeibacter sp. CCUG73630, a total substrate consumption of 97.2% was observed in M6 (glucose). However, in M5 (glucose and xylose), 82.6% of the substrate was consumed by Komagataeibacter sp. CCUG73630.
Table 2
Effects of media composition on BC yield, substrate consumption and pH by Komagataeibacter sp. CCUG73629.
| Mixed carbon Media | BC yield (%) | Total Substrate consumption (%) | pH |
| M1 | 211.0 ± 1.41c | 75.2 ± 1.10b | 3.8 ± 0.01c |
| M2 | 228.3 ± 1.06b | 55.4 ± 1.08d | 4.2 ± 0.01a |
| M3 | 119.5 ± 0.71e | 81.5 ± 1.59a | 4.0 ± 0.28b |
| M4 | 283.3 ± 1.06a | 62.6 ± 1.27c | 3.8 ± 0.01c |
| M5 | 176.5 ± 2.12d | 77.1 ± 1.28ab | 3.8 ± 0.01c |
| M6 | 100.0 ± 0.00f | 56.4 ± 1.12d | 3.7 ± 0.01d |
Keywords
M1 − Glucose + Arabinose + Xylose; M2 – Glucose + Cellobiose + Xylose + Arabinose; M3 − Glucose + Mannose + Xylose + Galactose + Arabinose; M4 − Glucose + Cellobiose; M5 – Glucose + Xylose; M6 – Glucose.
Table 3
Effects of media composition on BC yield, substrate consumption and pH by Komagataeibacter sp. CCUG73630
| Mixed carbon Media | BC yield (%) | Total Substrate consumption (%) | pH |
| M1 | 68.8 ± 0.17e | 76.9 ± 0.01c | 3.7 ± 0.03c |
| M2 | 77.8 ± 0.28d | 64.9 ± 0.16d | 4.0 ± 0.03a |
| M3 | 43.5 ± 0.27f | 60.0 ± 0.27e | 3.8 ± 0.01b |
| M4 | 91.0 ± 0.03b | 76.3 ± 0.22c | 3.6 ± 0.03c |
| M5 | 85.1 ± 0.02c | 82.6 ± 0.40b | 3.5 ± 0.01d |
| M6 | 100.0 ± 0.00a | 97.2 ± 0.12a | 3.7 ± 0.01c |
Keywords
M1 − Glucose + Arabinose + Xylose; M2 – Glucose + Cellobiose + Xylose + Arabinose; M3 − Glucose + Mannose + Xylose + Galactose + Arabinose; M4 − Glucose + Cellobiose; M5 – Glucose + Xylose; M6 – Glucose.
Substrate consumption of Komagataeibacter sp. CCUG73629 and Komagataeibacter sp. CCUG73630 during BC production in mixed carbon sources.
The pattern of substrate consumption by Komagataeibacter sp. CCUG73629 and Komagataeibacter sp. CCUG73630 in the mixed carbon source medium during BC production is shown in Fig. 1a-f. During BC production by Komagataeibacter sp. CCUG73629 in M1, the consumption of glucose, arabinose and xylose ranged from 18.0–1.9 g/L, 3.5–1.9 g/L and 6.4–3.3, respectively. By day 16, 89% of the glucose had been consumed. During BC production by Komagataeibacter sp. CCUG73630 in M1, the consumption of glucose, arabinose and xylose ranged from 18–1.3 g/L, 3.5–1.9 g/L and 6.5–3.2 g/L, respectively. By day 16, 92% of the glucose and 50% of the xylose were consumed.
In M2, during BC production by Komagataeibacter sp. CCUG73629, the consumption of glucose, cellobiose, xylose and arabinose ranged from 14–1.7 g/L, 7.4–7.1 g/L, 4–1.9 g/L and 2.5–1.5 g/L, respectively. After 16 days, 87% of the glucose and 3% of the cellobiose were consumed. During BC production by Komagataeibacter sp. CCUG73630 in M2, the consumption of glucose, cellobiose, xylose and arabinose ranged from 14–1.3 g/L, 8–5.8 g/L, 3.9–1.6 g/L and 3–1.9 g/L, respectively. By the 16th day, 91% of the glucose, 27% of the cellobiose and 58% of the xylose were consumed.
During BC production via M3 and Komagataeibacter sp. CCUG73629, the consumption of glucose, mannose, xylose, galactose and arabinose ranged from 10.8–0.9 g/L, 1.4–0.3 g/L, 6.4–1.4 g/L, 3.5–0.9 g/L and 5.5–5.5 g/L, respectively. After 16 days, 91% of the glucose and over 70% of the other sugars were consumed. During BC production by Komagataeibacter sp. CCUG73630, glucose, mannose, xylose, galactose and arabinose consumption ranged from 10.8–0.8 g/L, 1.4–0.9 g/L, 6.5–3.2 g/L, 3.5–2.9 g/L and 5.5–3.3 g/L, respectively. After 16 days, 92% of the glucose, 50% of the xylose and 18% of the galactose were consumed.
With the use of M4 during BC production by Komagataeibacter sp. CCUG73629, the consumption of glucose and cellobiose ranged from 21.6–4.3 g/L and 8.1–6.9 g/L, respectively. During production by Komagataeibacter sp. CCUG73630, the consumption of glucose and cellobiose ranged from 21.7–2.3 g/L and 8.0–2.8 g/L, respectively. After 16 days, Komagataeibacter sp. CCUG73629 consumed 79% of the glucose and 15% of the cellobiose, whereas Komagataeibacter sp. CCUG73630 consumed 89% of the glucose and 39% of the cellobiose.
During BC production with M5, Komagataeibacter sp. CCUG73629, the consumption of glucose and xylose ranged from 21.3–2.4 g/L and 6.2–3.5 g/L, respectively, whereas the consumption of glucose and xylose by Komagataeibacter sp. CCUG73630 ranged from 21.4–1.8 g/L and 6.2–3.0 g/L, respectively. After 16 days of BC production, 88% of the glucose and 43% of the xylose were consumed by Komagataeibacter sp. CCUG73629, whereas 91% of the glucose and 50% of the xylose were consumed by Komagataeibacter sp. CCUG73630.
Glucose consumption in M6 ranged from 28 − 12 g/L and 28.4–0.7 g/L by Komagataeibacter sp. CCUG73629 and Komagataeibacter sp. CCUG73630 during BC production. By the 16th day, Komagataeibacter sp. CCUG73629 consumed 57%, while Komagataeibacter sp. CCUG73630 consumed 97% of glucose.
Characterization of BC Produced with Mixed Carbon Sources
The chemical structures of the BCs produced from Komagataeibacter sp. CCUG73629 and Komagataeibacter sp. CCUG73630 in mixed carbon media are shown in the FTIR spectra in Figs. 2 and 3. The BCs produced by both strains were similar, with slight differences in peak positions and absorbances. The broad peaks at approximately 3338 and 3340 cm− 1 at both strains correspond to O–H stretching vibrations. The peaks at 2891 and 2895 cm− 1 indicate C–H group stretching. The peaks at approximately 1641 and 1651 cm− 1 correspond to O–H bending of the absorbed water. The peaks at 1427 and 1429 cm− 1 are associated with CH2 bending. The peaks at 1163 and 1161 cm-1 indicate asymmetrical C-O-C stretching. The peaks at approximately 1053 and 1055 cm− 1 indicate vibrations of C-C, C-OH and C-H rings and side groups. The peak at approximately 896 cm− 1 at both strains corresponds to CH vibrations.
The morphology of the BC produced by Komagataeibacter sp. CCUG73629 and Komagataeibacter sp. CCUG73630 in M1, M4 and M6 is shown in Fig. 4a-f. The BC micrograh showed a dense network of oriented fibers produced by both strains. The BC produced by Komagataeibacter sp. CCUG73629 in M1 and M4 was more compact and denser, with the fibres tightly aggregated, while the BC fibers prodcued by Komagataeibacter sp. CCUG73630 in M1 and M4 densely interwoven. In M6, both strainsproduced similar BC fibers that were densely interwoven.
The X-ray diffractograms of the BCs produced in M1, M4 and M6 presented two distinct characteristic peaks around 16.8\(\:^\circ\:\) and 22.7\(\:^\circ\:\) (Fig. 5). The degree of crystallinity and amorphous content of the BC varied with different carbon sources (Table 4). In M1, BC produced by Komagataeibacter sp. CCUG73630 had a greater degree of crystallinity (67.5%) than BC produced by Komagataeibacter sp. CCUG73629 (58.6%). However, the M6 BC produced by Komagataeibacter sp. CCUG73629 had a relatively high degree of crystallinity (66.7%).
Table 4
Degree of crystallinity and amorphous content of BC produced in mixed carbon media
| | Komagataeibacter sp. CCUG73629 | Komagataeibacter sp. CCUG73630 |
| BC produced in Mixed carbon media | Degree of Crystallinity (%) | Amorphous content (wt. %) | Degree of Crystallinity (%) | Amorphous content (wt. %) |
| BC_M1 | 58.6 | 41.4 | 67.5 | 32.5 |
| BC_M4 | 60.2 | 39.8 | 61.2 | 38.8 |
| BC_M6 | 66.7 | 33.2 | 58.1 | 41.9 |
Keywords
M1 − Glucose + Arabinose + Xylose; M4 − Glucose + Cellobiose; M6 – Glucose.