Evaluation of Enzyme Expression in a Macrophytic Treated Crude Oil Soil Habitat: Implication for Enhanced Phytoremediation Potential Using Transgenic Botanicals

Abstract

Background: Several studies have demonstrated the success of phytoremediation and its advantages over conventional physical and biochemical (even engineered transgenics) methods, resulting in its use on many contaminated sites. A direct method for enhancing the effectiveness of phytoremediation is to over express the genes in transgenic plants that are involved in metabolism, uptake and/or transport of specific pollutants. Objective: A screen-house ecological study was carried out to evaluate the remediation potentials of three species of the Fabaceae Family (Peltophorum pterocarpum, Leucaena leucocephala and Crotolaria retusa) for cleaning up soils contaminated with crude oil petroleum hydrocarbons. Result: Enzymatic analysis and hydrocarbon index assessment of the species and the vegetated and non-vegetated soils showed that P. pterocarpum recorded significant (p<0.05) performance over C. retusa and L. leucocephala in the uptake of hydrocarbons (oil and Grease (OG), Total Hydrocarbon Content (THC), organic carbon and organic matter content]. Results showed significant (p<0.05) reduction in enzyme expression and soil hydrocarbon index. C. retusa recorded significant (p<0.05) increase over P. pterocarpum and L. leucocephala in enzyme expression and reduction in foliar hydrocarbon index, with significant (p<0.05) increase in soil hydrocarbon index. Conclusion: Crotolaria retusa can thus be recommended as an integral component of any bioremediation technology package for hydrocarbon polluted terrestrial environment and by it transgenic enhancement of indigenous enzymes.

Studying the Physico-edaphic and Hydraulic Conductivity of Phytoremediated Spent Oil Polluted Habitat

“…This could suggest a longer period of phytoremediation duration as earlier affirmed by Wang et al [36]. The greater performance of P. pterocarpum in enhancing hydraulic conductivity could be attributed to its potency in improving the soil porosity, texture, structure, particle density and reduction in bulk density, organic matter and THC content as reported in this research and the influence of botanical explants (enzyme) in the rhizosphere soil [50].…”

“…This corroborate Merki et al [48], Wang et al [49], Wang et al [36], Udom and Nuga [37] who have earlier reported a similar higher degradation and removal of petroleum hydrocarbon in vegetated soils than non vegetated bulk soil. The performance of P. pterocarpum could be attributed to its extensive root system, which could be represented in a positive correlation (r = 0.40; P=0.05) between the plant root and THC content of the soil and also in the activities of the detoxifying enzyme of the plant [50]. The root system of plant species are capable of penetration into impermeable soil, thus it become desirable for phytoremediation to have plants that grows with dense ramified fibrous root system deep down [51].…”