Isolation and characterization of insoluble inorganic phosphate solubilizer rice rhizosphere strain Enterobacter cloacae BAU3

The objective of the present study was to isolate and characterize most efficient phosphate solubilizing bacteria (PSB) from rice rhizosphere. The study was carried out during the Kharif season’2018 at Department of Soil Science and Agricultural Chemistry, Bihar Agricultural University, Sabour, Bhagalpur, Bihar. The availability of phosphorous to plants for uptake and utilization is limited in soil due to fixation in the form of Fe-P, Al-P and Ca-P. The use of phosphate solubilizing bacteria can prove to be helpful measure to supply phosphorous to the crops to increase the productivity. In the present investigation, a total of 10 isolates were obtained from rice rhizosphere soil samples. All ten isolated isolates were shown phosphorus solubilization. Out of ten isolates BAU3 was found to be most potent phosphate solubilizers showing clear halo zone around its colony. The isolate BAU3 showed 20.00 mm phosphate solubilizing halo zone around its colony. The solubilization index (SI) of the isolate BAU3 was also calculated at the end of the incubation period and observed phosphate solubilization index (SI) of 3.22. The isolate BAU3 showed maximum insoluble phosphate solubilization of 450.24 ?g ml-1 and isolates BAU3 was selected for subsequent studies. The bacterial isolates BAU3 was gram negative, non-spore forming rods shaped. On the basis of the 16SrDNA sequencing, isolate BAU3 was identified as Enterobacter cloacae strain BAU3 (Genebank Accession No. MK033472). The isolated strain of bacterial has potential to solubilize insoluble phosphorus and it can be utilized for preparation of microbial inoculants or biofertilizers.