Abstract

A research was carried out in a tropical region to study the population of hydrocarbon utilizers in soil polluted with oily sludge. Plots were prepared to receive treatments with neat and emulsified oily sludge. These plots were further treated with fertilizer and bioaugmented with a consortium of hydrocarbon utilizers for six months. Results obtained indicated that, the presence of oily sludge in soil caused the growth of diverse genera of oil degraders. The major genera of bacteria active in polluted soil were Pseudomonas, Bacillus and Acinetobacter, while fungal general were Aspergillus, Penicillium, and Mucor. Abundant microbial growth was observed during the first 60 days. Some organisms such as Pseudomonas, Bacillus, Penicillium, and Aspergillus were present in polluted soil throughout the experimental period, while others includingCandida, Sporobolomyces and Rhizopus were found only during the first two months. Further analysis revealed that, succession of the hydrocarbon utilizers in polluted soil was subject to seasonal variations and depended primarily on the fraction of the oil being utilized at a specific time and also on the physiology of the micro organisms involved.  In addition, the selective appearance and succession of hydrocarbon utilizers in the polluted soil were affected only by the presence of neat and emulsified oil in soil as compare to other treatment parameters. The practical implication of these findings suggests that reloading of oil in some treated plots could be carried out after the first 90 days. Molecular techniques are underway to provide a more comprehensive study on this successional trend. 

Key words: Microbial succession and diversity, oily sludge, bioremediation, hydrocarbon utilizers.