The Potential of Established Turf Cover for Cleaning Oily Desert Soil Using Rhizosphere Technology

Abstract

The rhizosphere of two turf cover sorts; Bermuda grass and American grass contained high numbers, 8.1 to 16.8 × 10⁶ g⁻¹ of cultivable oil-utilizing and diazotrophic bacteria belonging predominantly to the genera Agrobacterium, Arthrobacter, Pseudomonas, Gordonia, and Rhodococcus. Those bacteria also grew on a nitrogen-free medium and demonstrated the ability to reduce acetylene to ethylene. These isolates grew on a wide range of n-alkanes (C9 to C40) and aromatic hydrocarbons, as sole sources of carbon. Quantitative determinations revealed that predominant bacteria consumed crude oil and representative aliphatic (n-octadecane) and aromatic (phenanthrene) hydrocarbons efficiently. The fact that those organisms had the combined activities of hydrocarbon-utilization and nitrogen-fixation makes them suitable tools for bioremediating oily desert areas that are normally poor in nitrogenous compounds. Phytoremediation experiments showed that spreading turf cover on oily desert soil inhibited oil volatilization and enhanced oil loss in soil by about 15%. Oil loss was also enhanced in turf free soil samples fertilized with NH₄NO₃. In conclusion, covering this oil-polluted soil with turf cover minimized atmospheric pollution, increased the numbers of the oil-utilizing/nitrogen-fixing bacteria by about 20 to 46% thus, encouraging oil attenuation.

KEYWORDS:

• microorganisms
• oil pollution
• phytoremediation
• rhizosphere
• turf cover

ACKNOWLEDGMENTS

This work has been supported by Kuwait University, Research Grant SL07/03. We would also like to acknowledge the usage of ABI 3130xl Genetic Analyzer and the GLC-equipment under the General Facility Projects GS01/02 and GS02/01.