Isolation and Characterization of Azotobacter on Traditionally Managed Land

Azotobacter is a genus of bacteria that plays an important role in the nitrogen cycle in the soil. They are known as nitrogen-fixing bacteria that can convert atmospheric nitrogen into a form that can be used by plants. Research on azotobacter is often carried out in the context of agriculture to improve soil fertility and crop yields. This study aimed to determine the population and characterization of azotobacter on traditionally managed land. Soil samples were taken from several types of land use including nutmeg plantation, cloveplantation, mixed plantation, forest, and shrubs soils. Azotobacter was isolated using NFM (Nitrogen-Free Mannitol) media, characterization refers to Bergey’s manual, and the bacterial population was counted by the total plate count method. The highest Azetobacter population was found in forest soil at 9.8 x 105, mixed plantation ranged from 7.1 x 105 CFU/gr soil ─ 7.3 x 105 CFU/gr soil, clove plantation 5.7 x 105 CFU/gr soil ─ 6.1 x 105 CFU/gr soil, hamlet plantation 4.4 x 105 CFU/gr soil ─ 4.7 x 105 CFU/gr soil, and the lowest population was found on land soil that had become shrubs at 4.6 x 103 CFU/gr soil. Characterization of eight selected bacteria showed that the colony shape consists of undulate, circular, lobate, filamentous, and undulate, the margin of the colony consists of lobate, undulate, and filamentous, the color of the colony is clear white and yellow, the elevation of the colony consists of flat, raised, and entire. The results of gram staining showed that all azotobacter isolates obtained are gram-positive with bacili and cocci cell shapes. This study implies that forest management with a mixed plantation system has soil biological properties that are close to natural conditions compared to other land uses.