Isolation and
characterization of plant growth promoting bacteria (PGPB) from the rhizosphere
of Spinacea oleracea L.
Jeevan Swetha and Sayantan D.
Res. J. Biotech.; Vol. 20(1); 77-87;
doi: https://doi.org/10.25303/201rjbt077087; (2025)
Abstract
As the years pass by, there is an increase in abiotic stress conditions around the
environment that directly or indirectly affect agriculture around the world. Therefore,
there is a dire need to increase the sustainability of plants. Plant Growth Promoting
Bacteria (PGPB) play an important role in maintaining the physiology and growth
of plants under various stress conditions. This study looks into the isolation and
characterization of different PGPB from Spinacia oleracea L. and their tolerance
against salinity and commonly used commercial pesticides against the Spinacia family.
The techniques used are isolation by serial dilution, 16sRna sequencing, characterization
of different PGPB assays for confirmation such as ammonia production, catalase test,
phosphate solubilisation, potassium solubilization, siderophore production, indole-3-acetic
acid production, biofilm formation assay, halotolerance and tolerance study using
Minimal Inhibitory Concentration (MIC). PGPB were isolated and characterized from
Spinacia oleracea L., which was under an abiotic stress environment.
Isolates were Bacillus clarus, Bacillus licheniformis, Paenibacillus alvei SJ6 and
Paenibacillus alvei SJ8, having quantities as high as 78.1±0.004 mgL-1 phosphate
solubilization, 43.8 mgL−1 of indole-3-acetic acid production, 14.566±0.011 psu
of siderophore production and 0.62 ±0.027 μmol mL−1 of ammonia production. All isolates
also had considerable amounts of halotolerance up to 10%, whereas Bacillus licheniformis
had 12.5% halotolerance. The bacterial isolates had considerable tolerance against
commonly used commercial pesticides against green leafy vegetables such as chlorpyriphos
+ cypermethrin combination and fungicides such as mancozeb. Therefore, this study
looks into the isolation of potential plant growth promoting bacteria that have
considerable amount of halotolerance and pesticide tolerance.
