Abstract:
A study on isolation and characterization of phosphate rock-solubilising
microorganisms from Minjingu and Panda Hill deposits was undertaken in order to examine their
potential for use as future inoculants. Following initial screening, 22 fungi and 39 bacteria from
Tanzania's Minjingu and Panda Hill phosphate rock deposits were assessed for their ability to
solubilise water-insoluble phosphate rocks. Five best bacterial and fungal isolates in terms of
total soluble P released were selected for molecular identification using 16S and 5.8S rDNA
sequencing for bacterial and fungal isolates, respectively. Overall, fungal isolates exhibited the
highest solubilising abilities, registering up to 80.39 mg kg−1 of phosphate rock compared to their
bacterial counterparts with best performer solubilizing only 27.45 mg kg−1 of phosphate rock.
While fungal isolates from both Minjingu and Panda Hill were generally more efficient at
solubilising samples from the less complex guano deposit of Minjingu (HMPR), the bacterial
isolates showed significant (P ≤ 0.05) variations with isolates from Panda Hill showing a far better
ability at solubilising their more familiar source of P, the igneous PandaHill phosphate rock (PPR)
samples. Aspergillus stelifer and A. tamarii were the most efficient fungal isolates freeing 20.97–
77.49 and 12.74–80.39 mg of soluble P kg−1 from PPR and HMPR, respectively. Similarly,
Stenotrophomonas maltophilia was the best bacterial isolate releasing up to 27.45 and 24.75 mg
of soluble P kg−1 from PPR and HMPR, respectively. The potential exhibited by microorganisms
characterized in this study warrants further enquiry for their application in the field.
