Table 3.
Duncan's multiple range tests for the effect of soil pH, salinity, iron, and C/N ratio on growth and CFUs of B. pseudomallei in the soil microcosm during the first 0–7 days at 37°C
| Factors | N | Number of colonies (log 10) | ||
|---|---|---|---|---|
| Minimum | Maximum | Mean | ||
| Soil pH | ||||
| 4 | 48 | 7.0414 | 8.7993 | 7.886556* |
| 5 (control) | 48 | 7.6532 | 9.7853 | 9.374871† |
| 6 | 48 | 7.9085 | 9.8261 | 9.460210‡ |
| 7 | 48 | 7.8976 | 9.6335 | 9.225175§ |
| 8 | 48 | 5.0128 | 7.5441 | 5.498369¶ |
| 9 | 48 | 0 | 6.6128 | 1.607606∥ |
| 10 | 48 | 0 | 6.3617 | 1.229073** |
| Total | 336 | |||
| Salinity (% NaCl) | ||||
| 0.0 (control) | 48 | 7.5185 | 9.7924 | 9.313283* |
| 0.25 | 48 | 7.6128 | 10.3304 | 9.688585† |
| 0.4 | 48 | 7.5635 | 10.0792 | 9.561938‡ |
| 0.5 | 48 | 7.6021 | 9.8513 | 9.419521§ |
| 0.7 | 48 | 7.5185 | 9.4472 | 8.847806¶ |
| 1.0 | 48 | 5.8675 | 7.7538 | 6.805060∥ |
| 2.5 | 48 | 0 | 7.6767 | 3.149660** |
| 5.0 | 48 | 0 | 7.6646 | 2.581748†† |
| Total | 384 | |||
| Iron (mg/kg) | ||||
| 50 control) | 48 | 7.0086 | 9.4955 | 8.828798* |
| 75 | 48 | 7.4314 | 9.4771 | 8.920146* |
| 100 | 48 | 7.4771 | 9.5441 | 9.062283† |
| 125 | 48 | 7.4914 | 9.9031 | 9.524765‡ |
| 150 | 48 | 7.5185 | 9.9395 | 9.539894‡ |
| Total | 240 | |||
| C/N ratio | ||||
| 10 (control) | 48 | 7.7160 | 11.5051 | 10.050983* |
| 15 | 48 | 7.6812 | 11.8062 | 10.126879† |
| 20 | 48 | 7.6335 | 11.6628 | 10.112454† |
| 25 | 48 | 7.6435 | 11.1461 | 9.925965‡ |
| 30 | 48 | 7.5051 | 10.0492 | 9.018746§ |
| 40 | 48 | 6.5051 | 9.6021 | 7.592454¶ |
| Total | 288 | |||
The number of colonies is from three replicates of two sets of independent experiments (total sample size = 6). Different footnotes represent significant difference.
Soil pH 4 significant difference from pH 5, 6, 7, 8, 9 and 10; Salinity 0.0% NaCl significant difference from 0.25, 0.4, 0.5, 0.7, 1.0, 2.5 and 5.0% NaCl; Iron 50 and 75 mg/kg significant difference from 100, 125 and 150 mg/kg; C/N ratio 10 significant difference from 15, 20, 25, 30 and 40.
Soil pH 5 significant difference from pH 4, 6, 7, 8, 9 and 10; Salinity 0.25% NaCl significant difference from 0.0, 0.4, 0.5, 0.7, 1.0, 2.5 and 5.0% NaCl; Iron 100 mg/kg significant difference from 50, 75, 125 and 150 mg/kg; C/N ratio 15 and 20 significant difference from 10, 25, 30 and 40.
Soil pH 6 significant difference from pH 4, 5, 7, 8, 9 and 10; Salinity 0.4% NaCl significant difference from 0.0, 0.25, 0.5, 0.7, 1.0, 2.5 and 5.0% NaCl; Iron 125 and 150 mg/kg significant difference from 50, 75 and 100 mg/kg; C/N ratio 25 significant difference from 10, 15, 20, 30 and 40.
Soil pH 7 significant difference from pH 4, 5, 6, 8, 9 and 10; Salinity 0.5% NaCl significant difference from 0.0, 0.25, 0.4, 0.7, 1.0, 2.5 and 5.0% NaCl; C/N ratio 30 significant difference from 10, 15, 20, 25 and 40.
Soil pH 8 significant difference from pH 4, 5, 6, 7, 9 and 10; Salinity 0.7% NaCl significant difference from 0.0, 0.25, 0.4, 0.5, 1.0, 2.5 and 5.0% NaCl; C/N ratio 40 significant difference from 10, 15, 20, 25 and 30.
Soil pH 9 significant difference from pH 4, 5, 6, 7, 8 and 10; Salinity 1.0% NaCl significant difference from 0.0, 0.25, 0.4, 0.5, 0.7, 2.5 and 5.0% NaCl.
Soil pH 10 significant difference from pH 4, 5, 6, 7, 8 and 9; Salinity 2.5% NaCl significant difference from 0.0, 0.25, 0.4, 0.5, 0.7, 1.0 and 5.0% NaCl.
Salinity 5.0% NaCl significant difference from 0.0, 0.25, 0.4, 0.5, 0.7, 1.0, and 2.5% NaCl.