Table 2.
Phenotypes associated with enzymes of poly P and ppGpp metabolism
| Phenotype | PPK1 | PPK2 | PPX1 | PPX2 | PPX1-PPX2 | PhoAcj | SpoT |
| Poly P metabolism | |||||||
| Poly P synthesis/accumulation | ↑ | - | - | - | - | ↑ | ↑ |
| Poly P-dependent GTP synthesis | - | ↑ | NT | NT | NT | NT | NT |
| Poly P degradation | - | - | ↑ | ↑ | ↑ | NT | NT |
| Maintenance of ATP:GTP ratio | NT | ↑ | NT | NT | NT | NT | NT |
| ppGpp metabolism | |||||||
| ppGpp synthesis | NT | - | ↑ | - | ↑ | NT | ↑ |
| Stress survival | |||||||
| Stationary phase survival and growth | - | - | - | - | - | - | ↑ |
| Survival under low CO2 | NT | NT | NT | NT | NT | NT | ↑ |
| Osmotic shock survival | ↑ | ↑ | ↑ | ↑ | ↑ | ↑ | NT |
| Low nutrient stress survival | ↑ | ↑ | ↑ | ↑ | ↑ | ↑ | NT |
| Aerobic stress survival | - | ↑ | NT | NT | NT | NT | ↑ |
| VBNC formation | ↑ | ↑ | NT | NT | NT | NT | NT |
| Natural transformation | ↑ | NT | NT | NT | NT | NT | NT |
| Antimicrobial resistance | ↑ | ↑ | NT | NT | NT | ↓ | R |
| Virulence-related | |||||||
| Motility | - | - | ↑ | ↑ | ↑ | NT | NT |
| Biofilm formation | ↓ | ↓ | ↑ | ↑ | ↑ | ↓ | NT |
| Resistance to complement-mediated killing | NT | NT | ↑ | ↑ | ↑ | NT | NT |
| Adherence | NT | - | NT | NT | NT | NT | ↑ |
| Invasion | - | ↑ | ↑ | ↑ | ↑ | ↑ | ↑ |
| Intraepithelial survival | ↑ | ↑ | ↑ | ↑ | ↑ | ↑ | ↑ |
| Chicken colonization | ↑ | ↑ | NT | NT | NT | ↑ | NT |
NT: Not tested; R: Tested only for Rifampicin resistance; -: Phenotype absent; ↑: Phenotype is positively regulated i.e., deletion of the gene reduces the phenotype when compared to wildtype; ↓: Phenotype is negatively regulated i.e., deletion of the gene enhances the phenotype when compared to wildtype.