Evaluation of Phosphate Solubilizing Pattern of Selected Bacterial Strains and their Agrobiotechnological Potential

Abstract

Phosphorus (P) is the second most essential macronutrient, after nitrogen, required for plant growth and development. Despite its abundance in the soil, most of P remains inaccessible due to fixation with metal ions in the soil. The utilization of chemical fertilizers to meet P requirements and enhance crop yield has resulted in negative consequences for the ecosystem, soil health, and balance of soil microbiota. To address this challenge, there is a need to develop a cost-effective, environmentally friendly, and sustainable approach. The present study involves the use of phosphate solubilizing bacteria (PSB) along with inorganic phosphate sources, which can convert unavailable phosphorus into soluble (available form) soil. In the current study, Bacillus strains were isolated from soil and screened for their phosphate solubilizing ability. Selected bacterial strains, S5 and S32 were optimized at different pH (5, 7, 9, and 11) with two different inorganic phosphate sources i.e. Ca3 (PO4)2 and AlPO4. Bacillus strains S5 and S32 showed the highest PSI value i.e. 2.714cm and 2.785cm at pH 7 and pH 5 respectively. In both quantitative and qualitative assessments, S5 and S32 showed maximum phosphate solubilizing ability for Ca3 (PO4)2 as compared to AlPO4 due to the presence of acidic phosphatases enzymes at different pH. Furthermore, the in-vivo experiment on Zea mays showed an increase in plant growth in the presence of Bacillus strains S5 and S32 and inorganic phosphate source as compared to positive control. Based on these results, it can be concluded that Bacillus strains S5 and S32 have the potential to solubilize precipitated phosphate and make it available for the plant. Thus, Bacillus strains S5 and S32 could be effective as alternative biofertilizers for agriculture sustainability.