Compounds present in oil sludge such as polycyclic aromatic hydrocarbons (PAHs) are known to be cytotoxic, mutagenic and potentially carcinogenic. Microorganisms including bacteria and fungi have been reported to degrade oil sludge components to innocuous compounds such as carbon dioxide, water and salts. In the present study, we isolated different bacteria with PAH-degrading capabilities from compost prepared from oil sludge and animal manures. These bacteria were isolated on a mineral base medium and mineral salt agar plates. A total of 31 morphologically distinct isolates were carefully selected from 5 different compost treatments for identifi cation using polymerase chain reaction (PCR) of the 16S rRNA gene with specifi c primers (universal forward 16S-P1 PCR and reverse 16S-P2 PCR). The amplicons were sequenced and sequences were compared with the known nucleotides from the GenBank. The phylogenetic analyses of the isolates showed that they belong to 3 different clades; Firmicutes, Proteobacteria and Actinobacteria. These bacteria identifi ed were closely related to the genera Bacillus, Arthrobacter, Staphylococcus, Brevibacterium, Variovorax, Paenibacillus, Ralstonia and Geobacillus. The results showed that Bacillus species were predominant in all composts. Based on the results of the degradation of the PAHs in the composts and results of previous studies on bacterial degradation of hydrocarbons in oil, the characteristics of these bacterial isolates suggests that they may be responsible for the breakdown of PAHs of different molecular weights in the composts. Thus, they may be potentially useful for bioremediation of oil sludge during compost bioremediation.

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Aims: To determine multiple degradation and resistance capabilities of marine bacteria isolated from Rivers State, Nigeria on petroleum pollutants and heavy metals. Study Design: Nine treatments and the controls designs were set up in triplicates containing              100 mL of sterile modified mineral basal medium in 250 mL conical flasks supplemented with 50, 100, 200 and 300 ppm of xylene, anthracene and pyrene each; 1 % of other petroleum pollutants and 300 ppm of heavy metals, nine marine hydrocarbon degraders and incubated at 24ºC for 5 - 7 days. The nine treatments and controls set ups designated as ANT1, XYL2, PYR3, ANT4, PYR5, ANT6, XYL7, XYL8, PYR9 and CTRL (Without hydrocarbons) were used to determine the multiple degradability of the marine bacteria.   Place and Duration of Study: Department of Microbiology, Faculty of Natural Sciences, Chukwuemeka Odumegwu Ojukwu University, Uli Nigeria between September, 2014 and March, 2017. Methodology: A laboratory scale study was carried on six composite samples of the sediment and water samples from the three studied areas using enrichment, screening, selection, molecular, growth effect and substrate specificity techniques. Results: The findings revealed that screening and selection for the indigenous bacterial isolates from the three studied areas resulted in the isolation of nine out of forty eight (9/48) of the potent strains representing 18.75 % of the total isolates with significant (P = .05) multiple degradation and resistance potentials but with different efficiencies on xylene, anthracene and pyrene, other petroleum products and heavy metals at 50 – 300 pm and 1 %. All the nine potent strains were fully characterized molecularly and phylogenetically and belong to the genera: Providencia, Alcaligenes, Brevundimonas, Myroides, Serratia, and Bacillus. Conclusion: Thus, these selected potent bacterial strains could significantly contribute in the development of a cost - effective bioremediation process on aromatic hydrocarbons and heavy metals contaminated environments in Nigeria.

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