Isolation and Identification of Highly Effective Phosphate Solubilising Bacterial Strain from Coastal Soils to Promote Rice Growth

Phosphorous (P) is the second most vital macronutrient for plants that plays a significant role in the growth and development. Among the total soil phosphorous, plants can use only 0.1% of available phosphate, hence making the availability of soluble phosphate a limiting factor for plant growth. In order to overcome poor phosphorous availability, phosphate solubilising microorganisms can be used to ensure agriculture production. Hence, the study was aimed to isolate, identify, and characterise a potent bacterial species from coastal soils that can efficiently solubilise phosphate for plant absorption. From the five soil samples, a total of nine different discrete bacterial colonies were identified and they were named as MGP-01, MGP-02, MGP-03, MGP-04, MGP-05, MGP-06, MGP-07, MGP-08, and MGP-09. The screening of phosphate solubilisation demonstrates that the greatest phosphate solubilisation ability was found in the MGP-04 strain. Furthermore, the greatest phosphate solubilisations under increasing NaCl concentrations were found in the MGP-03 and MGP-04 strain. The highest plant growth promoting properties such as IAA and GA production were found with the MGP-03 and MGP-04 isolates. Due to better phosphate solubility and plant growth promoting activities, bacterial isolate MGP-04 was selected for molecular identification and bioinoculation studies. The molecular phylogeny revealed that the bacterial isolate MGP-04 is belongs to Bacillus toyonensisspecies. The bioinoculation studies revealed that the greatest germination percentage (98.2%), root length (5.8 cm), shoot length (6.5 cm), and dry weight (159.1 mg/gm) of rice seedlings was found with the treatment of 1x107 bacterial concentrations. The present study concluded that the bacterial isolate MGP-04 can be used as a potential phosphate solubiliser and plant growth promoter to increase crop productivity in reclaimed soils.