Isolation and Characterization of Nitrogen Fixing Bacteria from Rhizospher Soil Collected from Shell Mele Agricultural Center, Southern Ethiopia

Temam Abrar Hamza, Zebiba Hussein, Rediet Mitku, Petros Ayalew and Tesfaye Belayneh


Full Length Research Paper  I Published December,2017


Journal of Agricultural Science and Food Technology  Vol. 3 (7), pp.117-124



The aim of this present study was the isolation and characterization of nitrogen-fixing bacteria from lab rhizospher and root nodule samples collected from Sheele Mele agricultural farmland, southern Ethiopia. Isolation of nitrogen-fixing bacteria was undertaken using Azotobacter and yeast extract mannitol agar medium. Accordingly, a total of 55 nitrogen-fixing microbes were isolated from lab rhizosphere and nodule samples. Further morphological and biochemical characterization was done for the selected isolates. All the selected isolates were found to be motile, gram-negative in spore test, positive in catalase test, negative in citrate utilization test, negative MR test, positive in VP test and positive in indole test. They have also rod-shaped cell. The colonies of LRR29 and LNR16 isolates are a creamy white colony and with poor absorption of Congo red dye when grown in Yeast Extract Mannitol Agar supplemented with Congo red. While the colony of LRA10 has milky white colour, circular configuration and raised elevation. These evidence help to confirm the identity of isolates, LRR29 and LNR16 belong to genus Rhizobium and also LRA10 belongs to genus Azotobacter. These potential isolates have plant growth promoting activity. Treatment of corn seeds with 10 ml microbial biomass produced from isolate LRA10 have enhanced the root length (up to 47%) and the shoot length (up to 42%) over water treated control. Further study is required to examine the impact of these bacterial isolates on the yield and seed quality before application as a biofertilizer.

Key Words:
Nitrogen Fixing, Bacteria, Rhizosphere, Root Nodule, and Isolates.

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