P-solubilizing Microorganisms from The Poteran Island, Madura

The Poteran Island faces natural problem of dryness and less fertile crop soil. It is containing more insoluble phosphate (P), while plant absorbs P in a soluble P form. P is one essential macronutrient that influences ex. crop maturity and production, disease resistance and energy conservation. This study was aimed to explore the existing indigenous phosphate-solubilizing microorganisms (PSM) in the island to be applied back as biofertilizer. As a comparison, a commercial liquid bioactivator was chosen and treated as the same.This study successfully isolated, purified, characterized and measured their ability to solubilize P. They were 4 fungal isolates tended to be as Aspergillussp (coded as A, B, C and D) and 12 bacterial isolates which were based on their chemical character tended to be Aeromonas sp (TA2 and TA5), Enterobacteriaceae (TA6), Corynebacterium sp (TA 7 and TA16), Bacillus sp (TA9, TA10, TA11 and TA13), Providencia sp (TA 12), Pseudomonas sp (TA14) and Staphylococcus sp (TA17). After 3-4 days incubated in a Pikovskaya medium, fungal isolate A, B, C and D showed index P solubility number of 15, 13, 6 and 8 respectively. But, bacterial isolates needed a longer incubation time (up to 10 days) to produce a clear zone around the growth colony. Bacterial isolates gave average P-solubility index about 30. The high index were 76 and 60 from isolate TA17 (Staphylococcus sp) and TA14 (Pseudomonas sp). As a comparison, 6 fungal isolates were found in a commercial liquid bioactivator with less P-solubility index of 5-10; which were Aspergillus flavus (O1), Aspergillus niger (O2), Trichoderma sp1 and sp2 (O3 and O4), and Rhizopus sp (O5)