Characterization Indigenous Phosphate Solubilizing of Bacteria (PSB) by in-Vitro from Dry Land of Northern Lombok
Lolita Endang Susilowati, Wahyu Astiko Nurjannah

Abstract
This study aimed to the characterization of PSB isolates related to the potential of each isolate in solubilizing phosphate qualitatively (Politkovskaya solid media) and quantitative (Politkovskaya liquid media). The research used the method descriptive experimental in the laboratory by using bacterial isolates that was identified from dryland namely Pseudomonas azotoformans, Acinetobacter baumannii, Bacillus paramycoides. This study consisted of two stages, namely I) solubilizing phosphate measurements qualitatively based on clear zones formed on the media and calculated by phosphate solubilizing index (SI) on days 2, 4, 6, 8, and 10. II) solubilizing phosphate measurements quantitatively with calculating absorbance values using a spectrophotometer, λ = 693 nm on the media that has been inoculated bacteria and incubated at day 0, 2, 6, 4, 8. 10. Media was not inoculated with bacteria used as a control. Measuring pH of the media on each day of incubation was done by using a pH meter. The results of the study showed that the characteristic of each isolate PSB to solubilize phosphate quantitatively and qualitatively differred. The qualitative of all three isolates produced SI values were: P. azotoformans of 1,777, B. paramycoides of 2,061, and A. baumannii of 2,124. The quantitative level of P (%) solubilize until the end of incubation were amounting of 0.07%, 0.09%, and 0.44%. Measurement of pH media in all three isolates tended to decrease during incubation. The pH of Isolates P. azotoformans from 6.24 to 4.87, A. baumannii from 6.24 to 4.32 and B. paramycoides from 6.24 to 4.3.

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