TABLE 2.
Summary of results of proteases secreted by 17 Xenorhabdus strains and phase variants detected by five methods
| Xenorhabdus species and strain or isolatea | Gelatin liquefaction assay resultb | Zymographic result for band following: |
Activity (×10−7 M min−1) on: |
|||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Substrate | SDS-PAGEc |
Native PAGEc |
||||||||
| Band A | Band B | Band C | Band 1 | Band 2 | Succ-AAPF-Sbzld | Fua-LGPAe | Fua-ALVYe | |||
| X. nematophila strains | ||||||||||
| DSM 3370 | + | Gelatin | (+) (s) | — | — | (+) (ll) | — | 2.5 (el) | 10.5 (l) | 6.0 (el) |
| Casein | — | (x) (l)f | — | — | (x) (ll) | |||||
| AN6/1 | + | Gelatin | — | — | — | — | — | 2.3 (el) | 0.0 (l) | 7.1 (el) |
| Casein | — | (x) (ll)f | — | — | — | |||||
| AN6/2 | + | Gelatin | (+) (s) | (+) (l) | 3.5 (el) | 6.5 (l) | 8.2 (el) | |||
| Casein | — | xx (l)f | — | — | (x) (ll) | |||||
| X. cabanillassii strains | ||||||||||
| Riobrave/1 | + | Gelatin | (+) (ll) | — | — | — | — | 23.0 (el) | 23.5 (l) | 11.0 (el) |
| Casein | — | (x) (l)f | — | — | x (ll) | |||||
| Riobrave/2 | + | Gelatin | (+) (ll) | — | — | — | — | 2.1 (el) | 10.6 (l) | 13.4 (el) |
| Casein | — | (x) (l)f | — | — | — | |||||
| X. bovienii strains | ||||||||||
| DSM 4766 | + | Gelatin | (+) (ll) | + (s) | — | (+) (s) | — | 22.0 (el) | 10.1 (l) | 10.4 (el) |
| Casein | — | x (ll) | (x) (s) | — | (x) (s) | |||||
| Kraussei | + | Gelatin | — | (+) (ll) | — | + (ll) | — | 67.0 (el) | 15.6 (l) | 31.9 (el) |
| Casein | — | xx (ll) | (x) (ll) | x (ll) | xx (l) | |||||
| X. kozodoii strains | ||||||||||
| Intermedium | + | Gelatin | (+) (s) | (+) (ll) | — | (+) (ll) | — | 6.1 (el) | 8.5 (l) | 9.3 (el) |
| Casein | — | xx (el) | (x) (ll) | — | x (ll) | |||||
| Anomali AZ | + | Gelatin | — | (+) (l)f | — | + (ll) | — | 3.1 (el) | 26.7 (l) | 39.0 (el) |
| Casein | — | (x) (el)f | (x) (l) | xx (ll) | xx (ll) | |||||
| Morocco | + | Gelatin | (+) (ll) | + (l) | — | + (l) | — | 18.0 (el) | 9.6 (l) | 8.7 (el) |
| Casein | — | xx (el)f | (x) (l) | xx (el) | xx (ll) | |||||
| X. poinarii strains | ||||||||||
| DSM 4768 | + | Gelatin | (+) (s) | ++ (l)f | — | (+) (ll) | — | 1.8 (el) | 11.3 (l) | 15.4 (el) |
| Casein | — | xx (l)f | — | — | (x) (ll) | |||||
| Cubanum | + | Gelatin | (+) (s) | + (l) | — | ++ (ll) | — | 7.9 (el) | 10.0 (l) | 11.9 (el) |
| Casein | — | xx (el) | (x) (ll) | — | xx | |||||
| X. beddingii DSM 4764 | + | Gelatin | — | ++ (el)f | — | (+) (ll) | — | 2.0 (el) | 8.3 (l) | 12.9 (el) |
| Casein | — | xx (el)f | — | — | (x) (ll) | |||||
| X. budapestensis DSM 16342 | + | Gelatin | — | + (s) | — | ++ (ll) | — | 2.8 (el) | 9.2 (l) | 13.7 (el) |
| Casein | — | xx (ll) | — | — | xx (ll) | |||||
| X. szentirmaii DSM 16338 | + | Gelatin | — | (+) (ll) | — | + (ll) | — | 4.7 (el) | 31.2 (l) | 11.9 (el) |
| Casein | — | xx (el)f | — | — | x (ll) | |||||
| X. ehlersii DSM 16337 | NT | Gelatin | — | + (el) | — | ++ (l) | — | 2.8 (el) | 14.4 (l) | 27.0 (el) |
| Casein | — | x (el)f | — | — | (x) (l) | |||||
| X. innexi DSM 16336 | NT | Gelatin | — | + (ll) | — | ++ (ll) | — | 4.5 (el) | 4.0 (l) | 10.6 (el) |
| Casein | — | xx (el)f | — | — | xx (ll) | |||||
The identities of strains are given in Table 1.
Symbols: +, clearing zone is visible; −, clearing zone is not visible. NT, not tested.
The semiquantitative ratings of the activity bands by zymography on the gelatin substrate were as follows: —, no activity; (+), weak; +, medium (easily detected); ++, strong. The semiquantitative ratings of the strongest activities for activity band by zymography on the casein substrate were as follows: —, no activity; (x), weak; x, medium; xx, strong. The time of first detection of an activity is shown in parentheses behind the semiquantitative ratings as follows: el, early logarithmic phase (0- to 4-h culture); l, logarithmic phase (4- to 8-h culture); ll, late logarithmic or early stationary phase (8- to 20-h culture); s, stationary phase (longer than 20 h growth). (For the optical densities in these phases, see the growth curves of two strains in Fig. 2. The zymographic activities are distinguished according to their electrophoretic mobility such that band A [SDS-PAGE] and band 1 [native PAGE] have the lowest mobility.)
The activities were measured using 50-μl supernatant of 4-h cultures.
The activities were measured using 50-μl supernatant samples of 24-h cultures. For the dynamics of production of Fua-ALVY-ase and Fua-LGPA-ase activities, see Fig. 2. The calculation of enzyme activities is given in Materials and Methods.
When the cultures were incubated longer than 20 to 24 h, the production of these activities declined.