TABLE 1.
Effect of CD gene disruption on total CD activities and L-cysteine plus L-cystine production in E. coli
| Strain | Growth (OD610)a after 15 h of cultivation in LB plus 30 mM l-cysteine | CD activity (mU/mg of protein)b in the absence and presence of l-cysteine
|
Concn of l-cysteine plus l-cystine after 72 h of cultivation in C1 + TS medium (mg/liter/OD562)c | |
|---|---|---|---|---|
| No l-cysteine | 10 mM l-cysteine | |||
| JM39 (wild type) | 4.0 | 20.6 ± 0.1 | 27.6 ± 0.1 | 590 ± 160 |
| JM39ΔtnaA | 2.2 | 15.7 ± 0.1 | 14.1 ± 0.1 | 1,290 ± 70 |
| JM39ΔmetC | 3.5 | 15.0 ± 0.1 | 27.6 ± 0.5 | 1,240 ± 100 |
| JM39ΔcysK | 3.5 | 18.2 ± 0.5 | 29.9 ± 0.1 | NTd |
| JM39ΔcysM | 3.6 | 17.9 ± 0.5 | 27.8 ± 0.1 | 1,100 ± 70 |
| JM39ΔmalY | 3.6 | 15.3 ± 0.1 | 27.1 ± 0.5 | 1,360 ± 90 |
| JM39ΔtnaA ΔmetC ΔcysM ΔmalY | NT | 9.1 ± 0.5 | 19.6 ± 0.1 | 1,080 ± 10 |
| JM39ΔtnaA ΔmetC ΔcysK ΔcysM ΔmalY | NT | 8.7 ± 0.5 | 11.5 ± 0.1 | NT |
a
The values are means from three independent experiments. The variations in the values were less than 10%.
b
One unit of activity was defined as the amount of enzyme required to produce 1 μmol of sulfide per min from l-cysteine at 37°C. The values are means ± standard deviations from three independent experiments.
c
The values are means ± standard deviations from three independent experiments.
d
NT, not tested since cysK-disrupted cells showed l-cysteine auxotrophy.