title: Isolation and characterisation of crude oil sludge degrading bacteria.
abstract: BACKGROUND
  The use of microorganisms in remediating environmental contaminants such as crude oil sludge has become a promising technique owing to its economy and the fact it is environmentally friendly. Polycyclic aromatic hydrocarbons (PAHs), as the major components of oil sludge, are hydrophobic and recalcitrant. An important way of enhancing the rate of PAH desorption is to compost crude oil sludge by incorporating commercial surfactants, thereby making them available for microbial degradation. In this study, crude oil sludge was composted for 16 weeks during which surfactants were added in the form of a solution.
  
  
  RESULTS
  Molecular characterisation of the 16S rRNA genes indicated that the isolates obtained on a mineral salts medium belonged to different genera, includingStenotrophmonas,Pseudomonas,Bordetella,Brucella,Bacillus,Achromobacter,Ochrobactrum,Advenella,Mycobacterium,Mesorhizobium,Klebsiella,PusillimonasandRaoultella. The percentage degradation rates of these isolates were estimated by measuring the absorbance of the 2,6-dichlorophenol indophenol medium.Pseudomonasemerged as the top degrader with an estimated percentage degradation rate of 73.7% after 7 days of incubation at 28 °C. In addition, the presence of the catabolic gene, catechol-2,3-dioxygenase was detected in the bacteria isolates as well as in evolutionary classifications based on phylogeny.
  
  
  CONCLUSIONS
  The bacteria isolated in this study are potential agents for the bioremediation of crude oil sludge.
authors.affiliation: Department of Environmental Sciences, University of South Africa, Johannesburg, South Africa ; Microbiology and Environmental Biotechnology Research Group, Agricultural Research Council - Institute for Soil, Climate and Water, Pretoria, South Africa.
authors.forename: Linda U
authors.initials: LU
authors.lastname: Obi
authors.affiliation: Institute for Science and Technology Education, University of South Africa, Pretoria, South Africa.
authors.forename: Harrison I
authors.initials: HI
authors.lastname: Atagana
authors.affiliation: Department of Environmental Sciences, University of South Africa, Johannesburg, South Africa ; Microbiology and Environmental Biotechnology Research Group, Agricultural Research Council - Institute for Soil, Climate and Water, Pretoria, South Africa ; Unit for Environment Science and Management, North-West University (Potchefstroom Campus), Potchefstroom, South Africa.
authors.forename: Rasheed A
authors.identifier: 0000-0002-8974-422X
authors.initials: RA
authors.lastname: Adeleke
keywords: 16S rRNA; Bacteria; Bioremediation; Catechol-2,3-dioxygenase; Composting; Crude oil sludge; Polycyclic aromatic hydrocarbon (PAHs)