Isolation and Characterization of 2,4-Dichlorophenoxyacetic Acid Degrading Bacteria from Rice Cultivated Soil in Kura Local Government Area of Kano State. Nigeria

Abstract

2,4-Dichlorophenoxyacetic acid (2,4-D) is a widely used pre-/post emergent systemic herbicide that controls broad-leaved weeds and other vegetation on rangelands purposely used for increasing agricultural yield, soil productivity, products quality, minimizing losses of agricultural products caused by crop pest. However, excessive use of this herbicide results in both soil and water pollution which is detrimental to humans, animals and the environment. Aboriginal bacteria normally occurring in low density in soil have been shown to degrade pesticides and other chemicals, such microbes have possibility for use in bioremediation of polluted environments. Isolation of 2,4-D degrading bacteria was accomplished through incubation experiments in mineral salt medium supplemented with 2,4-D. Aboriginal bacterial strain capable of using 2,4-dichlorophenoxyacetic acid as the sole carbon and energy source was isolated from Rice cultivated soil with a long-term history of herbicide use in Kura L.G.A, Kano State. The strain named K2-BUK-BCH was recognized as Pseudomonas plecoglossicida based on its 16S rRNA sequence analysis, morphological, and biochemical features. The degradation characteristics of strain K2-BUK-BCH were evaluated using one factor at a time approach (OFAT). The degradation conditions for 2,4-D were as follows: pH 8.0, 35°C, 200µgL-1 inoculum size, and 2,4-D concentration of 0.72gL-1.The degradation potential of 2,4-D was determine using high-performance liquid chromatography (HPLC). Up to 96.68% of the 2,4-D was degraded under optimal conditions after 6 days of incubation. Pseudomonas plecoglossicida sp was reported for the first time as able to degrade 2,4-D in Kano State, Nigeria. The isolated strain represents a great potential for bioremediation.