TABLE 1.
Summary of kinetic parameters of O2 evolution and H2 photoproduction in the wild-type Anabaena PCC 7120 and the ΔhupL mutant entrapped in thin Ca2+-alginate films
| Cycle no. | Strain/genotype | Kinetic profilea |
|||
|---|---|---|---|---|---|
| Maximum specific rate of H2 production (μmol/mg Chl a/h) | Net H2 photoproduction yield (mol/m2) | Maximum specific rate of O2 evolution (μmol/mg Chl a/h) | Net O2 evolution yield (mol/m2) | ||
| 1 | Anabaena PCC 7120 | 7.1 ± 3.0*** | 0.07 ± 0.02*** | 60.0 ± 8.8*** | 0.19 ± 0.01** |
| ΔhupL | 31.9 ± 9.1 | 0.31 ± 0.08 | 78.1 ± 10.0 | 0.33 ± 0.06 | |
| 2 | Anabaena PCC 7120 | 2.9 ± 2.1*** | 0.03 ± 0.02** | 18.2 ± 8.3 | 0.15 ± 0.01 |
| ΔhupL | 16.6 ± 4.5 | 0.23 ± 0.09 | 21.4 ± 8.2 | 0.24 ± 0.09 | |
| 3 | Anabaena PCC 7120 | 1.8 ± 0.8** | 0.01 ± 0.01* | 19.4 ± 9.4 | 0.16 ± 0.04 |
| ΔhupL | 10.9 ± 5.2 | 0.08 ± 0.05 | 22.3 ± 5.1 | 0.19 ± 0.03 | |
| 4 | Anabaena PCC 7120 | 1.5 ± 1.1* | 0.002 ±.0.001 | 15.6 ± 9.3 | 0.13 ± 0.06* |
| ΔhupL | 9.2 ± 7.0 | 0.05 ± 0.04 | 12.8 ± 7.2 | 0.07 ± 0.01 | |
| 5 | Anabaena PCC 7120 | 1.1 ± 0.8 | 0.001 ± 0.001* | 13.5 ± 9.1 | 0.12 ± 0.07 |
| ΔhupL | 4.9 ± 3.8 | 0.02 ± 0.01 | 14.4 ± 4.4 | 0.11 ± 0.06 | |
| Total | Anabaena PCC 7120 | 0.12 ± 0.02*** | 0.74 ± 0.11* | ||
| ΔhupL | 0.70 ± 0.18 | 0.93 ± 0.14 | |||
a
The long-term H2 photoproduction activities in immobilized cells were maintained by periodic purging of the headspaces of the vials with Ar supplemented with 6% CO2. Values represent an average of three independent experiments (with three vials in each) ± the standard deviations. Significant differences between the two strains are indicated as follows: *, P < 0.05; **, P < 0.01; ***, P < 0.001.