Isolation and identification of Azospirillum isolates from different paddy fields of North Bengal

Samples of rhizosphere soil, non-rhizosphere soil and roots of rice plants were collected from the particular locations of the 3 districts (Bogra, Naowgaon and Dinajpur) of North Bengal. Twenty different colonies of Azospirillum spp. were isolated from the different samples from which ten isolates were finally selected for detailed study on the basis of better growth in Nfb semi-solid medium. The selected isolates were M-1, M-2, M-3, M-4, M-5, M-6, M-7, M-8, M-9 and M-10. The selected isolates were thoroughly characterized on the basis of their response to a number of morphological and physiological tests. In this investigation, six selected isolates M-3, M-4, M-6, M-7, M-8 and M-10 were identified as A. lipoferum; three isolates M-1, M-2 and M-5 were identified as A. brasilense and one isolate M-9 was identified as A. halopraeferns. Variations were found in all of the isolates in colonial, morphological and physiological characteristics and in the ability of fermenting various carbohydrates. All of the selected isolates developed characteristics scarlet colonies on RC medium.