Development of an Efficient Bioremediation System for Petroleum Hydrocarbon Contaminated Soils Based on Hydrocarbon Degrading Bacteria and Organic Material Control

The efficiency of bioremediation systems can be improved using specific hydrocarbon degrading microorganisms, which necessitates enhancement of number, growth, and activity of these microorganisms. Long-chain cyclic (c)-alkanes are recalcitrant hydrocarbons in soil and water environments. Several long-chain c-alkane degrading bacterial strains have been isolated and characterized, and the numbers of bacteria have also been stimulated, with Rhodococcus erythropolis and Gordonia terrae being most efficient. Degradation efficiency and type of alkane hydroxylase gene were closely related, and bacterial number and hydrocarbon degrading activity were important factors for efficient bioremediation systems. Management of biomass (Total Carbon (TC), Total Nitrogen (TN), and C/N ratio) in the contaminated soil was found to be important to enhancement of the number and activity of Hydrocarbon Degrading Bacteria (HDB). When TC and TN were controlled (TC=20,000 mg/kg, TN=2,000 mg/kg, and C/N ratio=10) using organic materials, the number of HDB was stimulated and maintained for a long time relative to those in soil controlled with inorganic materials, resulting in improved bioremediation efficiency.