Identification and Characterisation of the Salt Tolerant Phosphate-Solubilising Bacterial Isolates for Enhancing Soil Fertility

Abstract

In this study, 13 bacteria were isolated from the agricultural soils of Kyaukse city, Myanmar, and out of these isolates, two bacteria isolates viz. JU-24 and JU-33 are found to be potent phosphate (P) solubilisers and are selected for further studies. These two isolates are identified as Bacillus megaterium based on the 16S rRNA gene sequence. When the growth rates of these two isolates were tested for salt tolerance, they could grow well in media with NaCl concentrations of 3%, 6% and 9%. For 0% and 3% NaCl concentrations, JU-33 (84.37 mg/L for 0% NaCl and 130.36 mg/L for 3% NaCl) showed higher P-solubilising efficiency than JU-24 (73.29 mg/L for 0% NaCl and 87.42 mg/L for 3% NaCl) for both NaCl concentrations when inoculated in Ca3(PO4)2 containing liquid medium. In media containing AlPO4 and FePO4 without NaCl, the P-solubilising activity of JU-24 is higher than JU-33 for these two substrates. Moreover, these strains showed noticeable levels of P solubilisation activity in the presence of various carbon sources indicating high P-solubilising efficacy. The soil inoculation experiment revealed that inoculating the experimental soil with JU-33 resulted in an obvious increase in available P, which increased from 13.08 mg/L in the non-inoculated soil to 18.40 mg/L in the inoculated soil with the bacterial isolate, JU-33. This study clearly showed that JU-24 and JU-33 isolates could be used as biofertilizers in ecological agricultural systems and may help to sustain environmental health and soil productivity. The use of biofertilizers can reduce the use of expensive chemical fertilisers, reducing planting costs and improving soil fertility through long-term use. Biofertilizers can help solve the problem of feeding an increasing global population at a time when agriculture is facing various environmental stresses and are affordable for low-income farmers.