Crude Oil-Degradation and Plasmid Profile of Nitrifying Bacteria Isolated from Oil-Impacted Mangrove Sediment in the Niger Delta of Nigeria

The crude oil degradability and plasmid profile of autotrophic nitrifying bacteria, Nitrosomonas and Nitrobacter species, isolated from mangrove sediment in the Niger Delta of Nigeria were studied. The effects of temperature, pH and optical density on the utilization of different carbon sources by the bacteria were also investigated. Results showed that nitrifying bacteria could utilize kerosene, diesel oil, jet fuel and engine oil as carbon sources. None utilized hexane and xylene but moderate growth was observed in benzene, phenol and toluene. However, their ability to utilized crude oil varied both in rates of utilization and in growth profiles. Mixed culture of the isolates degrades 52 % of crude oil introduced into the medium followed by Nitrosomonas sp. with 40 % degradation. The least was Nitrobacter sp. with 20 % degradation. The ability of the autotrophs to degrade crude oil was found to be plasmid-mediated through curing experiment and electrophoresis. The size of the plasmid involved was estimated to be 23 kb. The high crude oil utilization of the mixed culture implies that nitrifying bacteria isolated from contaminated ecosystem are excellent crude oil degraders and can be harnessed for bioremediation purposes

White-Rot Fungi in Bioremediation

Bioremediation is defined as the application of biological processes to the treatment of pollution. Most research on the field of bioremediation has focused on bacteria, and fungal bioremediation (mycoremediation) has also been attracting the interest just for a couple of decades. The toxicity of many pollutants reduces natural attenuation of bacteria, but white-rot fungi (WRF) can challenge with toxic levels of the most pollutants. Fungi are robust organisms having very high tolerance to toxic environments, and this feature makes them ideal to use for bioremedial purposes. White-rot fungi are basidiomycetes that are capable of degrading a lignocellulose substrate. Extracellular enzymes involved in the degradation of lignin and xenobiotics by white-rot fungi include several kinds of laccases, peroxidases, and oxidases producing H2O2. Nowadays, great progress in this area may derive from modern molecular technologies, which may provide cheaper potential sources of various enzymes by means of genetically modified microorganisms or plants. This chapter explains the bioremediation and its application conditions and degradation mechanisms of the harmful compounds such as textile dyes, PAHs, chlorophenols, TNT, pesticides, and nylon