TABLE 2.
Protease secretion by 20 Photorhabdus strains and phase variants: summary of results obtained with four detection methods
| Straina | Detection method
|
|||||||
|---|---|---|---|---|---|---|---|---|
| Gelatin liquefaction assayb | Zymography following:
|
Fua-LGPA-ase activity (kobs)c,d | ||||||
| SDS-PAGEc
|
Native-PAGEc
|
|||||||
| Php-A1 | Php-A2 | Php-C | Php-A | Php-C1 | Php-C2 | |||
| Brecon/1 | + | ++ (ml) | + (ll) | + (ll) | ++ (ml) | ++ (ll) | ++ (ml) | 11.5 (ml) |
| TT01/1 | + | (+) (s) | − | − | ++ (ml) | + (ml) | − | 21.2 (ml) |
| Rh/1 | + | + (ll) | − | − | + (ll) | ++ (ml) | − | 8.6 (ml) |
| Rh/2 | + | (+) (s) | − | − | (+) (s) | + (ml) | − | 3.8 (ml) |
| Indica/1 | + | ++ (ml) | (+) (ll) | − | + (ml) | ++ (ml) | − | 17.0 (ml) |
| Hm/1 | + | + (s) | − | − | + (ll) | + (ml) | + (ml) | 4.5 (ml) |
| Hm/2 | − | − | − | − | − | − | − | 9.3 (ml) |
| Hb/1 | + | ++ (ml) | (+) (ll) | − | + (ml) | − | − | 1.7 (s) |
| Hb/2 | + | (+) (s) | − | − | (+) (ml) | (+) (s) | + (s) | 3.8 (s) |
| NC1/1 | + | + (ml) | ++ (ll) | − | ++ (ml) | ++ (ll) | ++ (s) | 9.7 (ml) |
| NC1/2 | + | + (ml) | ++ (ll) | − | ++ (ml) | (+) (s) | − | 1.5 (ml) |
| Wx6/1 | + | (+) (s) | − | − | + (ml) | + (ml) | − | 4.3 (ll) |
| Wx6/2 | − | − | − | − | − | − | − | 2.2 (ll) |
| Wx8/1 | + | + (ml) | (+) (s) | − | + (ml) | (+) (ml) | ++ (ml) | 3.4 (II) |
| Wx8/int | + | ++ (ml) | (+) (s) | − | ++ (ml) | (+) (s) | − | 3.6 (ll) |
| Wx8/2 | + | + (ml) | (+) (s) | − | + (ml) | (±) (s) | − | 3.1 (ll) |
| HSH-2/1 | − | − | − | − | − | − | − | 2.1 (s) |
| HSH-2/2 | − | − | − | − | − | − | − | 3.2 (s) |
| K122/1 | + | (+) (ll) | − | + (s) | ++ (ml) | + (s) | ++ (ll) | 9.9 (ll) |
| K122/2 | − | − | − | − | (±) (s) | − | (±) (s) | 0.4 (ll) |
The identities of the strains are shown in Table 1.
+, clearing zone visible; −, clearing zone not visible.
Intensity of the highest activity: −, not detectable; (±), very weak; (+), weak; +, well easily detectable; ++, strong. The times of first detection are indicated in parentheses, as follows: ml, mid-logarithmic phase (optical density at 600 nm between 1.0 and 4.8; h 12 to 21); ll, late logarithmic phase (optical density at 600 nm between 4.8 and 5.3; h 21 to 40); s, early stationary phase (optical density at 600 nm between 5.3 and 6.6; h 40 to 50).
The values were determined in supernatants having optical densities at 600 nm between 4.9 and 8.1 (43-h cultures). kobs is the first-order rate constant and is expressed in seconds−1 (see Materials and Methods).