In Situ and Ex Situ Bioremediation of Soil Contaminated With Paraquat and Glyphosate
Forty one bacterial isolates were screened for their capability to utilize the herbicides, glyphosate (41%) and paraquat (23%) using standard microbiological techniques. Three capable isolates were identified as Bacillus cereus, Serratia marcescens and Staphylococcus sciuri. The screening test results (OD) for paraquat and glyphosate were 0.438/0.619, 0.272/0.410, and 0.239/0.340 for Bacillus cereus, Serratia marcescens and Staphylococcus sciuri respectively. The percentage degradation study‟s results showed that, for paraquat, the mixed culture had higher ability (62.77%) but for glyphosate, Bacillus cereus had higher ability (100%). Both paraquat and glyphosate gave higher residue content with ex situ 0.575 /0.572 than with in situ 0.376 /0.333 respectively. All the results were analyzed statistically using analysis of variance, t-test and correlational matrix. Comparing the different parameters obtained for paraquat and glyphosate, there is no significant difference between the mean values at P<0.05. The results revealed that, with appropriate concentrations of the herbicides, the isolates will utilize and degrade them to less toxic level. Bioremediation of glyphosate contaminated soil is more complete than that of paraquat contaminated soil.