Production of Liquid Bio Fertilizer by Using Azotobacter Species and Their Effect on Plant Growth

Due to the function of Azotobacter in nitrogen fixation and to their probable biotechnological applications, there are few challenges in developing an effectual approach for the selective isolation of these micro-organisms from soil. One hundred ninety-six Gram-negative strains were isolated from 35 soils sampled in central Italy, by using and comparing three different methods. The screening of soil samples by means of soil paste–plate method mutual with isolation on mannitol-agar proved to be the finest strategy in terms of consistency and selectivity. Moreover, preliminary recognition of free-living nitrogen-fixing isolates on differential LG medium exposed to be tremendously precise, since the majority of the isolates with Azotobacter-like morphology on such a average were presumptively identified as members of the family Azotobacteriaceae, by means of amplified ribosomal DNA restriction analysis.