Investigation of the Potential of Indigenous Bacteria of Siri Island in Remediation of Petroleum Contaminants

Regarding that Iran is one of the prominent countries possessing enormous oil resources of the world, the decontamination of oil-polluted soils by a cost-effective and beneficial method such as bioremediation is of great importance. Siri Island is one of the oil producing islands of Iran that has been contaminated by oil sludge during 1980’s. Therefore, studying the role of indigenous microorganisms in the bioremediation of contaminants is very important. In this study, by the aim of the simulation of natural environment, some microcosms were prepared from clean soil of the island and they were then contaminated artificially with defined amounts of oil compounds including alkanes mix and PAH’s blend; after the addition of nitrogen and phosphate sources and water, in a six-month study period, two factors were examined: contaminants degradation rate and heterotrophic bacterial count. The results indicated that after a six-month treatment period, in alkane microcosm, C13 had the lowest remaining amount and C20 was the highest. In PHA microcosm, the biodegradation rate was directly correlated with the number of the ring of the PAH molecule, and at the end of the experiment, all types of PAH’s (except five rings molecule of Benzo(α)pyren) were completely degraded. These results completely coincided with the increase of heterotrophic bacterial count. From these results, we can conclude that indigenous bacteria of Siri Island have a high potential for the biodegradation of oil hydrocarbons. Therefore, by developing new methods for stimulating their growth, we can prepare the conditions for the effective biodegradation of the contaminants of the island.