Variation of Lipase, Catalase and Dehydrogenase Activities during Bioremediation of Crude Oil Polluted Soil.

Abstract

Crude oil pollution pervades the communities of the Niger Delta region of Nigeria. The present study examines the changes in lipase, catalase and dehydrogenase activities in crude oil polluted soils remediated with arthrobacter and bacillus species isolated from a crude oil polluted soil in Ikarama-Okordia community of Bayelsa State, Nigeria. A total of ten polythene bags containing 10kg soil were used. The experimental control (natural attenuation), remediated A (arthrobacter species bioaugmented) and remediated B (bacillus species bioaugmented) had three polythene bags polluted with 100, 200 and 400ml crude oil respectively and one unpolluted polythene bag (control). Remediation lasted for 90days and analysis was carried out every 30days. The results showed a significant (p˂0.05) variation in the activities of the enzymes studied. Lipase activity increased as the volume of crude oil (contaminant) increased relative to time, however, the increment was more pronounced in the soil samples remediated with arthrobacter species than bacillus species. In all the soils (irrespective of the volume of contaminant), it was observed that there was a significant reduction in the activity of catalase between the unremediated (undergoing natural attenuation) and remediated sites (arthrobacter and bacillus species) from the unpolluted soil (control); this reduction was pronounced in the unremediated soil and the soil remediated with bacillus species. However, as bioremediation proceeded from days 0 to 90, there was resurgence in catalase activity especially in the soils remediated with arthrobacter species. Interestingly, dehydrogenase activity reduced relative to time in all the soil samples. This study concludes that crude oil contamination in soil has adverse effects on the activities of lipase, catalase and dehydrogenase; however, microorganisms in polluted soils use their biochemical machinery including enzymes to degrade pollutants.

KEYWORDS: Lipase, Catalase, Dehydrogenase, Bioremediation, Bacillus species, Arthrobacter species