Table 2.
Potential plant growth promoting characteristics of cultivable strains isolated from the shoot, the roots and the rhizosphere of BR and TO willow clones growing on metal-contaminated soil
| BR | TO | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Identification | cfu/g | SID | OA | IAA | Identification | cfu/g | SID | OA | IAA | |
| Shoot | Bacillus pumilus | 1.14E+04 | + | − | + | Unc. rhodococcus | 7.50E+05 | − | − | − |
| Bacillus pumilus | 2.29E+04 | − | − | + | Unc. γ-proteobacterium | 1.98E+06 | − | − | + | |
| Bacillus pumilus | 3.81E+03 | − | − | + | Bacillus cereus | 7.50E+05 | − | − | + | |
| Bacillus pumilus | 1.24E+03 | − | + | − | Bacillus cereus | 2.08E+05 | + | + | + | |
| Bacillus pumilus | 1.24E+03 | − | + | − | Bacillus cereus | 1.38E+05 | − | − | − | |
| Bacillus pumilus | 6.20E+02 | − | − | − | Bacillus cereus | 7.75E+01 | + | − | + | |
| Paenibacillus lactis | 2.15E+05 | − | + | − | Bacillus subtilis | 7.75E+01 | + | − | + | |
| Paenibacillus lactis | 8.39E+02 | − | − | + | Bacillus pumilis | 7.75E+01 | − | + | + | |
| Paenibacillus lactis | 8.39E+02 | − | − | − | Bacillus sp. | 7.50E+05 | − | − | − | |
| Pseudomonas syringae | 8.12E+02 | − | − | + | Bacillus sp. | 6.25E+04 | − | + | − | |
| Pantoea agglomerans | 2.89E+04 | + | − | − | Bacillus sp. | 2.08E+04 | + | − | − | |
| Pantoea agglomerans | 7.22E+03 | + | + | − | Bacillus sp. | 7.75E+01 | + | + | − | |
| Micrococcus sp. | 2.08E+05 | − | − | + | ||||||
| Acinetobacter johnsonii | 2.67E+05 | − | − | + | ||||||
| Chryseobacterium hominis | 1.33E+05 | − | − | − | ||||||
| Staphylococcus pasteuri | 1.39E+06 | − | + | − | ||||||
| Total (%) | 2.95E+05 | 16.11 | 76.24 | 13.48 | Total (%) | 6.65E+06 | 3.45 | 24.94 | 51.25 | |
| Root | Caulobacter sp. | 7.85E+05 | − | − | − | Bacillus cereus | 2.13E+04 | − | + | + |
| Caulobacter sp. | 1.96E+05 | + | − | − | Bacillus cereus | 1.50E+04 | + | − | − | |
| Bacillus pumilus | 2.10E+05 | − | + | − | Bacillus sp. | 1.10E+04 | + | + | − | |
| Bacillus pumilus | 5.26E+04 | + | − | − | Bacillus sp. | 2.75E+03 | − | + | − | |
| Bacillus pumilus | 5.26E+04 | − | − | − | Staphylococcus sp. | 1.25E+03 | + | − | − | |
| Rhizobium radiobacter | 5.58E+05 | − | − | − | Staphylococcus sp. | 3.75E+03 | − | − | − | |
| Staphylococcus sp. | 5.75E+03 | − | + | + | ||||||
| Staphylococcus sp. | 1.25E+03 | + | − | + | ||||||
| Staphylococcus sp. | 1.25E+03 | − | + | − | ||||||
| Streptomyces sp. | 1.73E+04 | − | + | − | ||||||
| Streptomyces punicolor | 1.38E+04 | + | + | − | ||||||
| Pseudomonas sp. | 5.75E+04 | + | + | + | ||||||
| Pseudomonas sp. | 1.88E+04 | + | − | + | ||||||
| Pseudomonas sp. | 1.25E+03 | + | − | − | ||||||
| Arthrobacter gandavensis | 1.25E+03 | − | − | + | ||||||
| Caulobacter sp. | 1.25E+03 | − | − | + | ||||||
| Total (%) | 1.85E+06 | 13.42 | 11.34 | 0.00 | Total (%) | 1.74E+05 | 68.72 | 74.89 | 61.41 | |
| Rhizosphere | Streptomyces sp. | 8.00E+05 | − | − | − | Unc. γ proteobacteria | 2.59E+05 | + | − | − |
| Leifsonia sp. | 1.28E+06 | − | − | − | Unc. γ proteobacteria | 1.18E+05 | + | + | − | |
| Dermacoccus sp. | 4.80E+05 | − | − | − | Bacillus sp. | 2.35E+05 | + | + | + | |
| Bacillus pumilus | 8.35E+05 | − | − | − | Bacillus sp. | 2.82E+05 | + | + | − | |
| Bacillus pumilus | 4.18E+05 | + | − | − | Bacillus sp. | 4.24E+05 | − | − | + | |
| Paenibacillus lactis | 1.33E+06 | − | − | − | Bacillus sp. | 1.18E+05 | − | − | − | |
| Caulobacter sp. | 2.00E+05 | + | − | − | Bacillus sp. | 3.53E+05 | + | − | − | |
| Caulobacter sp. | 2.00E+05 | − | − | + | Staphylococcus epidermis | 1.41E+05 | + | − | + | |
| Luteibacter rhizovicinus | 4.80E+05 | − | − | + | Staphylococcus capitis | 3.06E+05 | + | + | − | |
| Staphylococcus sp. | 1.18E+05 | − | + | − | ||||||
| Burkholderia pyrrocinia | 1.41E+05 | + | − | − | ||||||
| Burkholderia sp. | 4.00E+05 | + | − | − | ||||||
| Leifsonia spec. | 3.76E+05 | + | − | + | ||||||
| Variovorax sp. | 2.35E+05 | + | + | − | ||||||
| Caulobacter sp. | 1.18E+05 | − | − | − | ||||||
| Total (%) | 6.02E+06 | 10.26 | 0.00 | 11.30 | Total (%) | 3.62E+06 | 78.56 | 35.73 | 32.46 | |
cfu/g: colony-forming units per gram fresh weight; SID: siderophore production; OA: organic acid production; IAA: indole-3-acetic acid production. −: negative test; +: positive test. Total: cfu/g: total amount of isolated bacteria in shoot, root or rhizosphere; SID, OA, IAA, Cd (0.4), Cd (0.8), Zn (0.6) and Zn (1.0): percentage of bacteria associated with the shoot, root and rhizosphere that tested positive.