Table 1.
Screening of factors affecting the solubilization of Araxá rock phosphate by Aspergillus niger FS1 in a solid-state fermentation with sugarcane bagasse as substrate
| Factor | Low level (−1) | High level (+1) | Effecta |
|---|---|---|---|
| Sucrose (mg g−1)b | 25 | 50 | 0.686* |
| Mineralsc(ml g−1) | 0 | 1 | 0.104* |
| Initial pH | Unadjusted (4.6) | 7.0 | 0.044 |
| Moisture (ml g−1) | 5.7 | 8 | −0.360* |
| Temperature (°C) | 25 | 30 | −0.054 |
| Incubation time (days) | 7 | 13 | 0.014 |
| Inoculum size (conidia flask−1) | 105 | 107 | −0.030 |
| Rock phosphate (mg g−1) | 15 | 45 | 0.244* |
| Methanol (ml g−1) | 0 | 0.05 | −0.022 |
| Biochar (mg g−1) | 0 | 100 | 0.390* |
*Significant by the t test (P < 0.05).
a
Effect = m+ – m– (m+ and m− are the mean of solubilized P for the high and low level of each factor, respectively).
b
Values are expressed per gram of dry sugarcane bagasse added at the beginning.
c
A solution of minerals was used (adapted from Czapek's medium) (g l−1): MgSO4.7H2O, 3; KCl, 3; FeCl3.6H2O, 0.108.