Özet:

Nitrogen-fixing bacteria are widely distributed in nature where they reduce atmospheric nitrogen in soil or in association with plant. They have been found in a wide variety of terrestrial and aquatic habitats in both temperate and tropical regions of the word. Nitrogen-fixing bacteria are found in symbiotic associations with plants free living in soil. The objective of the present research was to isolate free living Nitrogen fixing bacteria from virgin soil samples in araku valley and assessment of their ammonia accumulation at saline conditions. 10 soil samples were collected in different place from virgin areas. For isolation of the free living nitrogen fixing bacteria, Nitrogen free media like Jensens Medium and Azotobacter Agar were used. Serially diluted soil samples were spread on the agar media and incubated for 48 hours. Eleven morphologically different bacteria were separated on made pure colonies on nutrient agar media. All bacteria were under go biochemical characterization which reveals that all these bacteria related to Azospirillum, Azotobacter and Clostridium. High ammonia liberating isolate MGN-10 was molecular characterizes as Azotobacter chroococcum and this soil application increase the plant growth in terms of growth parameters. 

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