Iranian Journal of Medical Microbiology

Background: Environmental pollution by petroleum compounds have turned into one of the global concerns. The aim of the present research was evaluation of the indigenous fungal strains of Iran to remove crude oil pollutants.

Materials and Methods: First, the contaminated soil samples were collected. The samples were enriched in minimal salts medium (MSM) medium with 1% crude oil and chloramphenicol for 3 weeks and the isolates were purified. The crude oil degradation was measured by total petroleum hydrocarbon (TPH) assay method at 420 nm. In order to confirm the amount of oil degradation by selected isolate, the residual hydrocarbon content was evaluated by FT-IR. Laccase activity in the presence of 1% crude oil was measured. Finally, the selected isolate was identified using morphological molecular (18s rRNA gene sequence analysis) methods.

Results: In this study 30 fungal strains were isolated. The isolate G-05 was selected as a premium isolate by TPH test. This strain showed that 66% degradation of petroleum hydrocarbons after 15 days. Residual crude oil analysis with FT-IR spectrophotometry showed that G-05 is able to degrade 90% of aliphatic compounds. Evaluation of laccase activity showed that this isolate can produced 1440 U/l of enzyme after 15 days. Presence of laccase activity in G-05 was showed that using of non-specific ligninolytic enzymes are the main mechanisms of oil hydrocarbons degradation in mentioned strain. The strain was identified as a member of Phaeosphaeria genus by molecular and morphological tests.

Conclusion: Fungi have high potential in bioremediation of contaminants such as crude oil pollutants; however, few studies have been carried out in this field. For the first time, the results of this study showed that Phaeosphaeria has a high potential in bioremediation of the oil contaminated soils.