Isolation and Characterization of Beneficial Bacterium from the Rhizosphere of Suaeda nudiflora in Sundarbans, India

Abstract

A study was carried out to isolate and characterize salt-tolerant beneficial bacteria from the soil collected from the rhizosphere of a halophytic plant (Suaeda nudiflora) from Gosaba, 24 Parganas (South), West Bengal, India located in the Sundarbans delta during January 2018. The physicochemical analysis of the soil showed that the soil was alkaline in nature with high salinity. The organic carbon, total nitrogen and available phosphorus status of the soil were low while the available potassium content was high. Bacterium N8 isolated from the rhizospheric soil possessed multiple growth-promoting activities i.e., the highest phosphate solubilizing efficiency (8.52 mg P g-1 of sugar), nitrogen-fixing capacity (0.7 mg of N g-1 of sugar), phosphatase enzyme activity and tolerance to salinity at 6% NaCl. A morphological study of this bacterium indicated that it was gram-positive, rod-shaped and was present in both single and chain form. The PCR amplification of genomic DNA (using 16S rDNA specific primers) showed a clear visible band at 1.5Kb. Sequencing of the amplicon followed by BLAST analysis depicted that the bacterium N8 exhibited the highest similarity (99%) with the genus Bacillus. The NCBI-Gen Bank accession number of the bacterium was SUB416213 N8 MH489431. The presence of members of the genus Bacillus in the rhizosphere soil of Suaeda nudiflora from Sundarbans is being reported for the first time. This study has led to a significant avenue for the use of the N8 bacterium as a potential salt-tolerant phosphate solubilizing bio-inoculum for improving nutrient availability in the coastal region.