Evaluating the growth performance of Two Azotobactor spp. In liquid glucose broth and tryptic peptone broth as inoculum for the production of bio-fertilizers

Biofertilizers with Azotobacter spp. releases available nitrogen to the plant rhizosphere. A media that yield a high viable inoculum cell count in a shorter incubation period is important for commercial production of biofertilizers. Current study evaluates the growth performances of Azotobacter chroococcum and Azotobacter vinelandii, two spp. commonly found in sugarcane rhizosphere, in two broth cultures: tryptic peptone broth (TPB) and liquid glucose broth (LGB) using optical density (OD) measurements at a wavelength of 620 nm over an incubation period of 12 - 15 hours. The analysis of variance revealed significant (p<0.001) species, broth and species × broth interaction on OD. Azotobacter spp. had a higher growth rate in the protein enriched TPB compared to LGB. Azotobacter chroococcum had a higher growth rate than A. vinelandii particularly in TPB. Despite the cost, A. chroococcum inoculum grown in TPB can be recommended for commercial biofertilizer production, due to yield and time advantage.