Biodegradation of petroleum hydrocarbon by indigenous microorganisms isolated from an oil contaminated groundwater site

Bioremediation of petroleum contaminated land and groundwater has been an interesting area in recent years. A microbial study was carried out at a petroleum contaminated groundwater site to have successfully isolated eight dominant strains of oil degradation from the oil contaminated groundwater samples. The results showed that the Prokaryotic actinomycetes possessed the best degradation rate, followed by other bacteria and fungi. Pairwise orthogonal combination showed obvious better degradation rates than single bacteria, indicating the presence of synergies. Mixed strains expressed poorer degradation rates, revealing the antagonistic effect. Dynamics experiment demonstrated TPH degradation curve conformed to the first-level reaction kinetics equation, degradation rate was in order of SF2>;SX3>;SZ1>;mixed bacterium. The half-life of petroleum contamination was 18.0, 16.4, 19.9 and 21.3 h respectively with the treatment of SX3, SF2, SZ1 and mixed bacteria, which displayed limited life cycle of the microorganisms. Supplement of additional inorganic nutrient and carbon sources raised their degradation ability. For specific compounds, alkane exhibited the similar degradation to TPH; refractory non-hydrocarbon compounds showed lower degradation rate, it was concentrated later since the transformation of alkanes, little change in benzene. The microbial activity experimental results showed that the biomass and dehydrogenase activity correlated with the biodegradation positively. This can provide an important evidence for remediation strategy of the contaminated site.