Tolerance and Utilisation of glyphosate by Plant Growth Promoting Bacteria (PGPB) isolated from rhizosphere soil of maize (Zea mays l)

Abstract

Glyphosate is widely used by farmers to control weeds. Its excessive use by farmers affects non-target organism, this study was designed to evaluate the abilities of rhizobacteria to utilize glyphosate. Plant growth promoting bacteria isolated from the rhizosphere of maize were assessed for tolerance of glyphosate. The ability of the selected glyphosate tolerant isolates (Bacillus mojavensis, Pseudomonas aeruginosa, Alcaligenes feacalis, Pseudomonas syringae and Bacillus cereus 20UMPNR) to utilize the carbon and phosphorus contents at concentration of 3.1 mg/ml, 7.2 mg/ml and 14.4 mg/ml were evaluated by measuring their optical density and cell biomass. . mojavensis, P aeruginosa, A. feacalis strain, syringae and B cereushad higher level of tolerance to 7.2, 50.0 and 100.0 mg/ml of glyphosate. The growth of the isolates at different time and concentrations were significantly different (P= 0.05). The results of utilization as phosphorus (P), carbon (C) and both C and P source showed that B cereus and P aeruginosa had higher P-utilisation at the end of incubation while the least was B mojavensis. Also, P aeruginosa showed the highest evidence of C- utilization and least by B mojavensis. The same trend was observed when glyphosate was used as phosphorus and carbon source. This study has revealed the ability of these isolates to tolerate and utilize glyphosate.