Improving the productivity and quality of black cumin (Nigella sativa) by using Azotobacter as N2 biofertilizer

AbstractThirty one rhizosphere soil samples were collected from different gavernorates and localities cultivated with different standing crops. Samples were used for the isolation of N2-fixer Azotobacter sp. isolates. The purified isolates were identified as Azotobacter chroococcum. The purified isolates were tested for their N2 fixation activity, phosphates dissolving ability, production of plant growth promoting substances, exopolymer secretion, siderophores production, salicylic acid formation, and some enzymatic production. Out of these purified isolates namely Azo.4, Azo.5, Azo.9 and Azo.23 found to be more significant in the production of the aforementioned activities as compared with the other purified isolates. The four purified isolates were tested for some biochemical activities (hormonal activity and enzymes production) and used to prepare the effective microbial inoculants for black cumin (Nigella sativa) seeds. Results show that mixed inoculation with the four biofertilizer strains and using half dose of recommended N2-fertilizer enhanced the densities of the total microbial microflora, phosphate dissolving bacteria, azotobacters colonization, CO2 evolution in the rhizosphere of the inoculated plants and plant growth features in comparison with uninoculated plants (control). The effect of the crude oils of the produced black cumin seeds on some human pathogenic bacteria was studied. It was found that the crud fixed oil extracted from the seeds of plants has powerful antibacterial properties against this diverse genus of bacteria. However, the influence was different and depending on the tested bacterial strain

Effect of carrier materials, sterilization method, and storage temperature on survival and biological activities of Azotobacter chroococcum inoculant

AbstractAzotobacter chroococcum (A101) was examined for some biological activities such as nitrogenase, phosphatase, potassium solubilization, and production of some plant hormones such as indole acetic acid, gibberellic acid, and cytokinin. Six different formulations were prepared, using different carrier materials namely; peat moss, mixture of peat moss plus vermiculite 1:2 (w/w), wheat bran, rice husk, clay, and sodium alginate. Each carrier material was packed using polyethylene pages, and then divided into three groups. The first group was sterilized by autoclaving at 121°C for 20min, and the second one was sterilized by gamma irradiation at a dose rate of 4.0kGy for 1h. However, the third group was left without sterilization. Half of the inoculated polyethylene bags, containing the tested formulations either sterilized by autoclaving or gamma irradiation, were incubated at 8°C and the other bags were incubated at 30°C for 6months. The non-sterilized bags were incubated under the same condition but only for 3months. For testing the survival of Az. chroococcum (A101), the prepared formulation samples were taken every month during the storage period. Nitrogenase activity was evaluated in the prepared formulations which exerted survival cells equal to or more than 108CFU/ml after 6months of storage period. Results revealed that non-sterile formulations exerted high numbers of total fungi and bacteria along the storage period; however, Az. chroococcum (A101) numbers were decreased over incubation time. No contaminants have been detected in all sterilized carriers. Az. chroococcum (A101) inoculated on wheat bran exhibited the highest densities among the tested carriers. Encapsulated formulation of alginate exerted the high stability in Az. chroococcum (A101) densities up to the end of the incubation period (6months) at both 30°C and 8°C, being 11.905log10CFU/g

Biosorption of uranium and heavy metals using some local fungi isolated from phosphatic fertilizers

AbstractA number of 26 fungal cultures were isolated from different phosphatic sources, including phosphate fertilizers and rock phosphate. The highest number and percentage of isolates were obtained from tri-phosphate fertilizer and rock phosphate samples (9 isolates with 34.6% for each sample) and then 8 isolates with 30.8% from monophosphate fertilizer. These isolates were tested for heavy metals biosorption on solid medium supplemented with different metal ions at concentration of 50ppm. Eighteen out of 26 isolates were able to grow on solid medium containing heavy metals. The selected isolates were also screened for removal of heavy metals with different concentrations (0–150ppm) in liquid medium. Among 18 fungal cultures, 5 isolates were chosen for their high capability to tolerance of high concentration of heavy metals (150ppm), and it was found that the fungal growth was promoted in the presence of U, Cr5+ Cu++ for FR1 (0.026, 0.133 and 0.128g/100ml), Cr5+ for FR7 (0.246g/100ml), Zn++, Co++ and Pb++ for FR13 (0.219, 0.371 and 0.303g/100ml), U for FR15 (0.174g/100ml) and Zn++, Co++ and Pb++ for FR16 (0. 203, 0.385 and 0.312g/100ml). These isolates FR1 & FR7, FR13, FR15 & FR16 belong to genus Aspergillus as identified by their morphological properties, respectively