ABSTRACT

Oil pollution is a worldwide threat to the environment and the remediation of oil contaminated soils, sediments and water is a major challenge for environmental research. Bioremediation is a useful method for soil remediation. The objective of this study was to isolate Actinomyces from the soil using membrane filter techniques and at the same time use the isolates for remediation. Results showed polluted soil contained average of 46.51% of total petroleum hydrocarbon (TPH) prior to remediation. Two Actinomyces isolates were obtained, characterized (phenotypically and genotypically) and identified as Streptomyces carpaticus and Streptomyces xiamenensis respectively and subsequently used for bioremediation trials. At an inoculation size of 1.0x10⁸ cfu/ml and a trial period of 90 days. The total petroleum hydrocarbon concentration in the soil was reduced by 75.51% for Streptomyces carpaticus and by 75.96% for Streptomyces xiamenesis. Slight variations were recorded in the rate of degradation of TPH by the two isolates. The rate of remediation was in the range of 1.066% per day to 0.396% per day in treatment 1 (S. carpaticus) and 0.926% per day to 0.386% per day in treatment 2 (S. xiamenensis). Remediation rates decreased with time in both treatments. The efficiency of bioremediation process in treated soils increased with time from 31.74% (day 15) to 65.61% (day 90) in treatment 1 and from 27.04% (day 15) to 64.61% (day 90) in treatment 2. The Total Heterotrophic  Bacteria Count (THBC) increased to maximum population of 6.13x10⁸ cfu/g and 6.17x10⁸ cfu/g in the soils respectively, there were however no significant reduction in the total petroleum hydrocarbon of the control soil and that was attributed to possible metabolism of the hydrocarbon by indigenous organism. The potentials of the two Actinomyces isolates for polluted soil was established by the finding of the work.