Assessment of the Biodegradation of Herbicides by Bacteria Isolated from the Soil

Abstract

Assessment of the Biodegradation of Herbicides by Bacteria Isolated from the Soil Aim: The aim of this research is to assess the biodegradation of herbicides by bacteria isolated from the soil. Study Design: This study is designed to isolate, identify and characterize bacteria from the soil, to determine the degradation of herbicides by the bacterial isolates. Place and Duration of Study: Department of Microbiology, Nasarawa State University Keffi, Nasarawa State, Nigeria, between January 2017 and December 2017. Methodology: Bacteria were isolated from two different soil samples using pour plate method. The isolated bacteria include the species of Bacillus, Pseudomonas and Staphylococcus aureus which were grown on three different herbicides, containing mineral salt medium to determine their biodegradation potential. And degradation was measured by optical density checked using a spectrophotometer at 3 days interval. Results: The result revealed degradation of the herbicides by the isolates. All isolates were able to utilize the glyphosphate in the medium and as such growth was noticed. Out of the three isolates used (Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus), the best degradation observed was by B. subtilis at 82.61% on glyphosphate, followed by P.aeruginosa at 69.67% on Glyphosphate and finally S. aureus at 47.83% also on glyphosphate. The result also revealed low percentage degradation of the other herbicides by these organisms. Microorganisms were able to degrade glyphosate due to their ability to utilize the organophosphorus as the sole phosphorus source. Conclusion: From this study it can be deduced that the isolated bacteria can be used for bioremediation of herbicide contaminated and polluted soil although further studies may be required to standardize the procedure.