Indian Journal of Research in Pharmacy and Biotechnology Md. Mozammel Hossain et al. ISSN: 2321-5674(Print); 2320 – 3471(Online) IJRPB 3(1) www.ijrpb.com January-February 2015 Page 74 Isolation and identification of Azospirillum isolates from different paddy fields of North Bengal Md. Mozammel Hossain*, Iffat Jahan, Salina Akter, Md. Nazibur Rahman, S. M. Badier Rahman Department of Biochemistry and Molecular Biology, Jahangirnagar University, Savar, Dhaka-1342, Bangladesh. *Corresponding author: Email: mhossain@juniv.edu;Telephone: +8801717635098 ABSTRACT 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 their 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. Form the confirmation to the identification based on the characteristics of these isolates Bergey’s Manual of Determinative Bacteriology was followed. 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. Key words:Azospirillum, isolates, isolation, inoculation, identification, biofertilizer, North Bengal. INTRODUCTION The use of biological approaches for increasing crop production are usually less expensive, harmless and in the reach of all the countries. The utilization of biological nitrogen fixation (BNF) technology can also decrease the use of urea-N, prevent the depletion of soil organic matter and reduce environmental pollution to a considerable extent. Application of biofertilizers can not only reduce chemical fertilizer consumption by 20 to 50 per cent but also can simultaneously increase the yield of crop by 10 to 20 per cent (Saikia and Borah, 2007). The bacteria belonging to the genus Azospirillum (K-subclass of proteobacteria) are known for many years as plant growth promoting rhizobacteria (PGPR) (Okon, 1994). They were isolated from the rhizosphere of many grasses and cereals (Deboreiner and Day, 1976). Both in greenhouse and in field trials, Azospirillum was shown to have beneficial effects on plant growth and crop yields (Boddey et al. 1986). It is capable of producing associative symbiosis in the roots of various plants including grain crops such as rice and wheat. Inoculation of plants with Azospirillum has been found to cause significant increases in growth and yield of different crops including rice and wheat. Yield response to bacterization with Azospirillum inoculants was almost equivalent to that attainable due to application of 15-20 kg N/ha. A yield increase in rice due to inoculation of Azospirillum is reported to be in the 5–60% range (Kumar and Balasubramanian, 1986). This organism has wide adaptability to different environmental conditions. Under stress condition Azospirillum can enhance plant growth by fixing atmospheric nitrogen and by some other ways like production of growth promoting substances and influencing root development, causing increased uptake of nutrients from the land, and inhibiting pathogenic fungi and bacteria in the rhizosphere. Different BNF systems are in use on a limited scale in Bangladesh agriculture. Before large- scale extension of BNF systems at the farm level, further research is needed. So, the present work was undertaken to isolate and identify Azospirillum spp. from the rhizospheres of paddy fields. MATERIALS AND METHODS Collection of samples:Rice fields of particular locations of three different districts of North Bengal- Bogra, Naowgoan and Dinajpur were selected for sample collection. The locations were three villages (Bezura, Chalkvalli and Pattakur) of Shahjahanpur Upzilla and one village (Adorsha para) of Adamdighi Upzilla of Bogra; three villages (Sahapur, Dhamkuri and Vobanipur) of Naowgaon sadar Upzilla of Naowgaon and three villages (Sheikhpur, Hindupara and Gunjapara) of Dinajpur sadar Upzilla of Dinajpur. Rhizosphere soils were collected from the rhizosphere regions of the plant at the depth of 2-3 cm and non-rhizosphere soil sample was collected from 6 feet away from each plant. The plants were uprooted for root sample and the soils attached to the roots were removed. All samples were taken in different polythene bags and brought to the laboratory. The samples were preserved in refrigerator.