Isolation and Characterization of Azotobacter from Neems Rhizosphere

Abstract Nitrogen-fixing bacteria can be isolated from rhizosphere plants, and one of the N2-fixing bacteria is Azotobacter. One of the plants that can grow well in dry and barren soil conditions is Neem (Azadirachta indica A. Juss)(Mimba). The purpose of this study was to determined any Azotobacter isolated from the rhizosphere of the neem plant. The type of research is an experimental study, tracing the diversity of Azotobacter in the rhizosphere of the neem plant. The study was conducted by taking soil samples from the rhizosphere of neem plants on the Bali Island. Morphological characterization based on colony observation in terms of shape, color, margin, and texture. The isolated cells were determined based on Gram staining and determination of the presence of spores. Isolates were characterized by various biochemical methods namely nitrate, reductase, citrate utilization, methyl red, VP test, catalase (method of slip-cover), and oxidase tests. The soil sample was taken from rhizospheres of 5 plants. The results showed that the N2-fixing bacteria isolated in the five soil samples were Azotobacter paspali and Azotobacter vinelandii (Azomonas) groups. Actinomycetes were found when isolating using specific media Azotobacter on plant 2.