Isolation and Phosphate Solubilization of Beneficial Rhizobacteria from Cassava Soil

Abstract

Rhizobacteria as the root colonizing microorganisms show a significant impact on plant growth and development. The aim of this study was to isolate rhizobacteria with the ability to solubilize phosphate (P) from cassava (Manihot esculenta Crantz) rhizosphere. Soil samples of cassava rhizosphere of Piroon 2 (PR2) cultivar were collected at 6 months after planting (MAP). The population of culturable P-solubilizing bacteria (PSB) indicated that their population (1.92152 x 1011) was higher than nitrogen fixing (N-fixing) bacteria. The N-fixing bacterial population presented only 12% of PSB. In this study the nine better PSB were isolated from the cassava rhizosphere. These isolates showed the lag and log phases during the 240 and 420 min, respectively. The generation rates of bacterial isolates were in the range of G=15.49 min (NS23) and G=35.70 min (NS24). Isolates showed the significant difference to solubilize P on solid and liquid NBRIP medium. The result showed that isolate NS39 was significantly better than the other isolates. The diversity of isolates to solubilize P was in the range of 0.1 to 0.3 mg/L P. The isolates NS39 and NS14 could be better candidates for field and biotechnological applications