Browsing by Author "Simfukwe, Ester Jimmy"

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    Isolation and characterization of phosphate rock-solubilizing microorganisms from soils and rock phosphate samples of Panda Hill and Minjingu, Tanzania
    (Sokoine University of Agriculture, 2016) Simfukwe, Ester Jimmy
    Plants acquire P from soil solution as the phosphate anion. Phosphorus for plant can be obtained from soluble P fertilizers or from insoluble phosphate rocks. It is highly fixed by calcium and by Fe and Al oxides depending on soil pH. Phosphorus solubilizing microorganisms play a major role in P nutrition through solubilisation of insoluble phosphate rocks. The use of phosphate solubilizing microorganisms as inoculants increases P uptake by the plant and crop yield. This study was undertaken in order to isolate microorganisms which are capable of solubilizing rock phosphate. A total of 22 fungal and 39 bacterial isolates were isolated from soil and rock phosphate samples previously collected from Minjingu and Panda Hill phosphate deposits, Tanzania. The isolated strains were assessed for their ability to solubilize insoluble phosphorus from rock phosphate samples. Out of the isolated fungal or bacterial isolates, 10 isolates that gave larger diameters of the halo zones in media containing rock phosphateas sole source of P were selected for further studies. Selected isolates were quantitatively tested in broth containing either Panda Hill or Minjingu phosphate rock. Five isolates from each group that were selected as outstanding performers, based on their relative amounts of soluble P released, were identified using molecular techniques. The most efficient fungal isolates was Aspergillus tamarii which, while it solubilised only 12.774 mg P/kg of Panda Hill rock phosphate, was able to solubilize 80.39 mg P/kg of Minjingu rock phosphate. The most efficient bacterial isolate was Stenotrophomonas maltophilia which solubilised 27.45 mg P/kg of Panda Hill rock phospahte and 24.75 mg P /kg of Minjingu rock phosphate. Other isolates that performed well included Aspergillus flavus and Aspergillus stellifer fungal species and bacteria were Bacillus safensis and Acenotobacter baumanii. The outstanding performers are herein recommended as being potential inoculants for use in increasing crop yields.
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    Rock phosphate-solubilising potential of fungal and bacterial isolates from soils surrounding panda Hill and Minjingu phosphate rock deposits in Tanzania
    (International Society for Tropical Ecology, 2018) Simfukwe, Ester Jimmy; Tindwa, Hamisi Juma
    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.