Azotobacter salinestris: A Novel Pesticide-Degrading and Prominent Biocontrol PGPR Bacteria

Abstract

The species Azotobacter belongs to plant growth-promoting rhizobacteria (PGPR) group and are ubiquitous, aerobic, free-living and nitrogen (N-2)-fixing bacteria commonly living in soil, water and sediments. Being the major group of soilborne bacteria, Azotobacter plays different beneficial roles by producing different types of secondary metabolites in the soil such as vitamins, amino acids, plant growth hormones, antifungal substances, hydrogen cyanide and siderophores. These secondary metabolites have direct influence on growth of shoot, root and seed germination of many agriculture crops. Among different species, Azotobacter salinestris is considered as efficient in N-2 fixation (29.21 mu g Nm/L/day), production of indole acetic acid (24.50 mu g/mL), gibberellic acid (GA) (15.2 mu g/25 mL) and phosphate-solubilizing activity (13.4 mm). Molecular and biochemical studies confirmed the identity of the isolates (A. salinestris KF470807). A. salinestris found tolerant to a highest NaCl concentration (6-8%), to maximum temperature (45 degrees C) and also to varied pH ranges (8-9). The isolate was tested for pesticide resistance and biodegradation studies and showed 100% biodegradation of pendimethalin and did not recorded pendimethalin residues. It was also studied for antifungal efficacy against phytopathogen Fusarium species and influence on growth parameters of cereals. A. salinestris helps to replace chemical fertilizer and restore the soil fertility and crop productivity for the sustainable agriculture.