Isolation and Molecular Characterization of Phosphate-Solubilizing Bacteria from Root Nodules of Cowpea (Vigna unguiculata) Seeds Planted at Ota, Ogun State, Nigeria

Abstract

In line with the race to increase worldwide food production to cater to the growing world population, there is a growing interest in exploring the plant growth-promoting attributes of rhizobia. This is in a bid to curb environmental and health damage arising from the use of chemical fertilizers. Hence, the objective of this work was to isolate and characterize phosphate-solubilizing bacteria from root nodules of cowpea (Vigna unguiculata) seeds planted at Ota, Ogun State, Nigeria using standard techniques. The 16S rRNA gene amplification and sequencing of the organisms identified the 2 isolates which were positive for phosphate solubilization as Pseudomonas straminea and Ralstonia mannitolilytica. Their sequences were deposited to GenBank with the assession numbers MK590690 and MK590695 respectively. Isolate Pseudomonas straminea was more efficient and produced a halo zone (16mm) with a phosphate solubility index (PSI) of 2.0 while isolate Ralstonia mannitolilytica produced a halo zone (14 mm) with PSI of 1.6 after 7 days of incubation. The results obtained from this study indicate that these organisms could be potential candidates to be used as biofertilizers to improve crop yield.