Diversity of Azotobacter Isolates from Different Rice Soils of Tamil Nadu

Azotobacters are unique biofertilizers to maintain the N level in agricultural soil and synthesize the plant growth promoting hormones as indole acetic acid and gibberellins. Azotobacter EPS in the soil habitat play key roles in ecosystem functioning through controlling nutrient cycling reactions essential for maintaining soil fertility and also contributing to the genesis and maintenance of soil structure under conventional, biotic, and abiotic stressed soil environment. Each member of the bacterial population had varying responses to environmental factors and phenotypic variation in accordance with it genotype, so that required a grouping or classification to facilitate the study of bacterial diversity. The purposes of this study were to characterize Azotobacter species isolated from rice rhizospheres in different regions of Tamil Nadu and to determine the relationship between the species diversity of Azotobacter. The Azotobacterial isolates were characterized by utilizing a numerical taxonomy method based on phenotypic characters, including morphological, biochemical and physiological characters. The results indicated that AztRMD2 performed better than the standard strains. This study contributes to identify Azotobacter species isolated from rice rhizospheres in Tamil Nadu and to characterize EPS producing and cyst forming properties of Azotobacter spp. The results of this study may be of importance in allowing better utilization of Azotobacter biofertilizers.