Abstract:

Glyphosate (N-phosphonomethylglycine) is the most commonly used herbicide worldwide. Due to concern regarding its toxicity for non-targeted species in soil, finding glyphosate-degrading microorganisms in soil is important as these bacteria can grow by utilizing glyphosate as a source of carbon. Two bacteria species were isolated from soils of Baghdad. Morphological characteristic and biochemical reactions indicated these species were identified as Bacillus and Serratia marcescens. These bacterial isolates showed an ability to consume glyphosate as energy and sole carbon source at 20 mM. The growth of bacteria in the media containing glyphosate was determined after two days of incubation at 30 C by measuring turbidity (O.D) at 680 nm. The maximum growth of Bacillus in halogenated compound containing media was found to be (O.D=0.3836) after two days of incubation as compared to control media (O.D=0.0170)  without halogenated compound. In comparison to Bacillus, Serratia marcescens showed less growth activity (O.D=0.06) in halogenated compound containing media after two days of incubation as compared to its growth in control media (O.D= 0.03). The maximum chloride ion released due to dehalogenase enzyme activity was higher for Bacillus (O.D=1.3199) as compared to S. marcescens (O.D= 0.3) with respect to their control media (O.D =0.0491 and 0.04) respectively. This result gives hint regarding the role of dehalogenase present in the bacteria for their affinity to substrate and utilizing it for their growth. For a better understanding of dehalogenase enzyme produced by these two bacterial species, more research has to be explored for their possible use as bioremediation tools in the natural environment.

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