Nitrogen (N) is the most important mineral nutrient required by plants. Although some plants can directly utilize N, ammonium (NH4+) and nitrate (NO3-) are the only forms of N that are usable to most plants. Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are the key drivers that are responsible for the conversion of N into usable forms. Due to the importance of ammonia oxidizers (AOs), factors affecting their abundance and activity have been a major research focus over the years. This review focuses on the diversity of AOs, the factors that affect their abundance and activity in different soil types and the mechanism of nitrification. An improved understanding of the combinatorial effects of highly active AOs and methods for limiting nitrate loss from soils may enhance the management of nitrate in soils and improve plant yields.

The present study was conducted for the isolation of potential bacteria from the desert soil, their molecular identification and prediction of restriction sites of the potential isolate using the bioinformatics tools. Production of the metabolites was done by inoculating in nutrient broth of pH 8.6. Metabolite was bluish-green in color; it was extracted and dried by using methanol and used for partial characterization by using GC-MS spectroscopy. Antibacterial activity was performed with the clinical human pathogenic isolates. The bacterium was identified as Pseudomonas sp.JJTBVK on the basis of 16S rRNA sequencing. The sequence was analyzed for the restriction cleavage sites, which showed that the sequence had various restriction sites for different enzymes. Antibacterial activity (MIC) of methanol extract of the bacterial culture broth showed antibacterial activity (MIC), which was 29, 30, 30 and 29 mm for Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi, respectively. GC-MS analysis of the methanol extract showed the presence of naphth [2,3-B] azet-2 (1H) -one, 1-phenyl-, which was the characteristic compound showing the antibacterial activity.

This study was done to examine the rhizobacteria from field grown Genetically Modified (GM) maize and its non-GM counterpart. Rhizospheric soil samples were collected at 30 days after sowing (DAS) and at post-harvest from two experimental fields in Gauteng, South Africa. Total rhizobacteria (cfu/g) in GM and non-GM soil samples was not significantly different across the different media 30 DAS and at post-harvest. Rhizobacterial isolates obtained were biochemically characterized using the analytical profile index. Species of Pseudomonas, Aeromonas, Sphingomonas, Burkholderia, Stenotrophomonas, Achromobacter, Ewingella and Bacillus were screened in vitro for plant growth promoting traits such as, ammonia production, catalase activity, indole acetic acid production, phosphate solubilisation, hydrogen cyanide production and antifungal activity. All the 32 rhizobacterial strains tested in this study were positive for catalase activity, ammonia production and IAA production; 90.6% were positive for phosphate solubilisation, 34.3% for indicate antifungal activity but none for hydrogen cyanide production. These findings contributed to the quest for potential biofertilizers and biocontrol agents for sustainable agriculture.