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.