Efficiency of crude oil degradation and peroxidase production by indigenous bacteria isolated from Ogoni land, River State, Nigeria

Abstract

Detrimental impacts of crude oil spills on life below water require urgent intervention. With the emergence of microbial remediation technology as a viable strategy for clean-up of oil spill, low degradation efficiency by many bacteria remains a major challenge. Exploring new bacterial isolates with improved crude oil degradation efficiency is therefore crucial. In this study, bacterial isolates from crude oil contaminated site in Ogoniland, Rivers State, Nigeria were screened for ability to grow on crude oil and glucose (control) as sole carbon sources. Three isolates exhibited higher growth on crude oil based medium (COBM) than on glucose based medium, and were identified using 16S rRNA sequencing as Bacillus cereus and Paenibacillus alvei strains 1 and 2. They were further investigated for their growth kinetics, degradation efficiency and total peroxidase production on varying concentrations of crude oil (30, 50 and 75 g/L) at 30°C and 180 rpm for 288 h. Results revealed exponential decline in residual crude oil during the logarithmic growth phase of the three bacteria. Total peroxidase activity increased as crude oil degradation progressed. Highest enzyme yields of 1.79 U/mg, 1.39 U/mg and 1.69 U/mg were recorded from B. cereus, P. alvei strain 1 and P. alvei strain 2, respectively at 240 h of cultivation in 50 g/L COBM with degradation efficiency of 87.52%, 90.90% and 84.95%. Remarkably, these bacteria showed ≥ 80% crude oil degradation efficiency at the peak of peroxidase production which suggests that the enzyme played significant role in crude oil degradation by the bacterial isolates.