Table 4.
Growth rate (μ), generation time (g), biomass production, EPS concentration, PHB content, and EPS:biomass and PHB:biomass ratios of Azospirillum brasilense Ab-V5 grown in different culture media and evaluated at different periods of culturing in the culture medium OAB (Bashan and de-Bashan, 2015) and in Form15 (this work).
| Parameters | Culture time (h) | |||||
|---|---|---|---|---|---|---|
| 12 | 36 | 60 | ||||
| OABa | Form15a | OAB | Form15 | OAB | Form15 | |
| μ (h−1) | 0.68 ± 0.06 b | 0.88 ± 0.02 a | 0.29 ± 0.003 d | 0.39 ± 0.003 c | 0.11 ± 0.002 e | 0.18 ± 0.005 e |
| g (h) | 1.09 ± 0.09 e | 0.82 ± 0.03 f | 1.95 ± 0.01 c | 1.65 ± 0.01 d | 2.92 ± 0.02 a | 2.40 ± 0.03 b |
| Biomass (g L−1) | 0.19 ± 0.03 e | 1.11 ± 0.10 c | 0.37 ± 0.13 de | 2.05 ± 0.01 b | 0.55 ± 0.07 d | 2.37 ± 0.05 a |
| EPS (g L−1) | 0.13 ± 0.08 c | 2.15 ± 0.52 b | 0.18 ± 0.18 c | 2.93 ± 0.49 b | 0.22 ± 0.30 c | 3.97 ± 1.30 a |
| PHB (mg L−1) | 1.35 ± 0.02 e | 6.09 ± 0.22 e | 122.24 ± 1.43 d | 341.60 ± 2.62 b | 244.34 ± 1.12 c | 455.92 ± 4.60 a |
| EPS:biomass ratio (g:g) | 0.70 ± 0.28 b | 1.93 ± 0.33 a | 0.48 ± 0.11 b | 1.43 ± 0.15 a | 0.41 ± 0.07 b | 1.68 ± 0.38 a |
| PHB:biomass ratio (mg:g) | 7.04 ± 1.01 d | 5.48 ± 1.35 d | 332.79 ± 35.61 b | 166.80 ± 7.02 c | 445.67 ± 37.18 a | 192.37 ± 15.33 c |
a
OAB: modified NFb culture medium (Bashan and de-Bashan, 2015); Form15: culture medium described in this work. Bacterial cultures were grown in 1000 mL shaker flasks filled with 250 mL of culture medium and maintained at 28 ± 2°C and 150 rpm shaking frequency. Significant differences (P < 0.05) according to Tukey's test are indicated by small letters when comparing contrasts in rows.