Background: Accidental oil spills in the Nile River represents a public health concern in Egypt. Bioremediation of oil-contaminated water is efficiently competitive and economically effective compared to mechanical and chemical methods.
Aim: The current study aimed to: i) assess using environment-friendly materials as carriers for immobilizing oil-degrading bacteria and ii) evaluate applying these biocarriers for removal of oil from water in a batch experiment.
Materials and methods: Four bacterial strains Pseudomonas aeruginosa, Cronobacter sakazakii (recently named Enterobacter sakazakii), Klebsiella oxytoca and Bordetella bronchispetica were immobilized on grinded corn qgualh, Egyptian loofah, palm leaf raffia and sponge. Immobilizing bacterial consortium was carried out by incubating bacteria with carriers at 37°C with shaking at 120 rpm for three days. Biofilm formed on biocarriers was checked using scanning electron microscopy. Biocarriers with immobilized bacterial consortium were used for the removal of oil. Experiments were carried out in flasks each containing 100 ml of mineral salt broth fortified with 1 g/l light crude oil. Flasks were incubated at 37°C with shaking at 120 rpm for nine weeks. Total viable bacterial count and oil and grease were determined weekly.
Results: Oil and grease measurements showed a significant removal that reached 68.3, 71.5, 77.7 and 81% for grinded corn qgualh, Egyptian loofah, palm leaf raffia and sponge respectively. Flasks inoculated with sponge biocarriers showed rapid oil removal compared with other biocarriers. Gas chromatography-mass spectrometry (GC-MS) showed a percentage removal that reached 87% for compounds C11 to C32 in case of sponge carrier.
Conclusion: Immobilizing bacteria on biocarriers showed a good biofilm formation. Immobilized bacterial consortium showed rapid and efficient oil removal in bioremediation processes. Sponge showed dense bacterial colonization and consequently biofilm formation compared with other biocarriers.
Keywords: Biodegradation; environment-friendly biocarrier; immobilization; light crude oil.