Phenotypic and Genotypic Characterization of  Rhizobium species isolated from the root nodules of  Sesbania sesban found in Mumbai and its suburban  areas

Nishtha K. Singh Dr. Umesh Luthra Dr. Neetin Desai

Volume : III, Issue : VII, July - 2013

Phenotypic and Genotypic Characterization of Rhizobium species isolated from the root nodules of Sesbania sesban found in Mumbai and its suburban areas

Nishtha K. Singh Dr. Umesh Luthra Dr. Neetin Desai

Abstract :

Root nodulating bacteria were isolated and characterized from the root nodules of Sesbania sesban leguminous plants growing in regions of Mumbai and its suburban areas. A total of seventeen isolates isolated on Yeast Extract Mannitol Agar medium. These isolates were further studied for their morphological characters and biochemical characterization along with one reference culture (NCBI–TUR1). Out of seventeen, morphologically six Rhizobium strains were rod shaped, Gram negative and mucous producing. These Isolates were unable to grow in the presence of 0.1% Methylene blue and Lactose. With the help of biochemical characterization, it was confirmed that those all six isolates were Rhizobium species. After the phenotypic characterization, Polymerase chain reaction and 16S rRna gene sequencing were used for the genotypic analysis of Rhizobium species. Out of seventeen isolates only six strains were selected as Rhizobium after nif gene amplification. Further six isolates were selected as fast growing Rhizobium species based on Bromothymol Blue test. These Isolates were studied for different salt concentration range from 5– 9.0%, and culture shows less growth as the concentration of salt increased .All isolates grow at pH 6.0 to 11.0 but none of the isolates grow at ph 12.0. The optimum physical parameters for growth of fast growing rhizobia were found in pH between 7.0–8.0 and 28ºC temperature. BIOLOG test was performed in order to understand the nutrient requirement and utilization pattern of Rhizobium species, The goal of isolation of Rhizobium species associated with Sesbania sesban sample would be the assessment of Rhizobial genetic diversity .The tolerance to high sainity , pH and their survival in such harsh environmental conditions make these rhizobial isolates valuable to improve the productivity of the leguminous plants cultivated under extreme environments.