Glyphosate Degradation by Two Plant Growth Promoting Bacteria (PGPB) Isolated from Rhizosphere of Maize

This study was aimed at evaluating the possible utilization of glyphosate tolerant plant growth promoting bacteria (Pseudomonas aeruginosa and Bacillus cereus) for bioremediation of glyphosate polluted soil. The soil samples were spiked with 3.1 mg/ml, 7.2 mg/ml and 14.4 mg/ml of glyphosate and then inoculated with Pseudomonas aeruginosa and Bacillus cereus, level of glyphosate pollution before and after inoculation with the bacteria were determined using Gas Chromatography-Mass Spectroscopy (GC-MS) after extraction with acetonitrile. The bacteria showed significant ability to degrade glyphosate. Pseudomonas aeruginosa, Bacillus cereus, their mixed culture and control recorded percentage degradation of 76.11, 85.8, 75.8 and 49%, respectively at 3.1 mg/ml of glyphosate while At the concentration of 7.2 mg/ml, the percentage degradation by P. aeruginosa, Bacillus cereus, mixed culture of the isolates and control was 84.9, 72.7, 66.4% and 39.2%, respectively. The isolates also showed significant rate of degradation at the concentration of 14.4 mg/ml. The GC-MS results showed a significant variation in the degradation products obtained when compared with control. This study revealed that substantial amount of glyphosate was degraded by P. aeruginosa and Bacillus cereus. Hence, they may have great potential in bioremediation of glyphosate polluted soil.