Alkane-degrading bacteria and heavy metals from the Nakhodka oil spill-polluted seashores in the Sea of Japan after five years of bioremediation

This paper describes the isolation of alkane-degrading bacteria from the Nakhodka oil spill-polluted seashores in the Sea of Japan. Seven representative strains were identified using 16S rDNA sequence analysis as Bacillus spp., Pseudomonas sp., and Paracoccus spp. All bacterial strains showed their ability to grow well on aliphatic hydrocarbons, but not on aromatic hydrocarbons. In addition, elemental levels in heavy oil showed wide ranges in all the heavy oil samples consisting of Si, S, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb. Compounds of Si, S, and Cr were observed at high levels, while those of Ti, Mn, Fe, Co, Ni, Cu, Zn, and Pb were observed at low levels. Of all heavy metals, Co appeared to be toxic for all bacterial growth at concentrations of >1 ppm, while the presence of Ti, Cr, and Cu at 0.01 to 10 ppm were found not to inhibit growth of all bacterial strains. It is suspected that the presence of heavy metals may have a significant effect on the composition of the bacterial community, (i.e., alkane-degrading bacterial isolates), as well as on the biodegradative processes of the Nakhodka oil spill during the 5-year bioremediation.