Characterization of Drought Tolerant Actinobacteria from Rhizospheric Soil

Abstract

Drought is a major cause for reduction in crop yield and agricultural productivity around the Globe. The application of drought tolerance Actinobacteria to agroecosystem improves the growth and protect from water scarcity and they can be better alternative for natural farming and sustainable agriculture for aride and semi-aride regions. Herein, we isolated ten morphologically different actinobacteria from the rhizospheric soil of Datura and Khejri plants which are surviving in the nature without any special treatment provided. All the isolated bacteria were screened in-vitro for their drought tolerance capability for different time intervals against polyethylene glycol 8000 (PEG8000) with 5%, 10% and 10% concentration to media  which produce moisture stress in which medium bacteria were growing. Among them best five bacterial isolates were selected and named RADM1-RADM5 for further experimentation.  Physiological characterizations were done through their ability to grow in different temperature, pH ranges and NaCl concentration supplemented with the 5% PEG8000. Morphology of the bacteria was Gram’s positive and mycelium producing same as typical Actinobacterial species and for biochemical diversity stains were able to IMVIC test and carbohydrate utilization through IMVIC test. Enzymatic observations of isolates were resulted positive for nitrate reduction, catalase production and negative for starch hydrolysis. PCR amplification and 16S rRNA gene sequencing in BlastN found maximum similarity of three species RADM1, RADM2, RADM4 with Streptomyces clavuligerus and two species RADM3 and RADM5 with Rhodococcus erythropolis and submitted to NCBI gene bank database with accession number PQ114139 (RADM1), PQ120343 (RADM2), PQ114109 (RADM3), PQ120390 (RADM4), PQ039766 (RADM5).