The present study aimed to isolate and identify bacteria resistant to copper ions (Cu²⁺) and capable of degrading crude oil from the vicinity of a copper mine. The optimal conditions affecting the biodegradation of crude oil in the presence of Cu²⁺ were also investigated. Herein, a unique strain with the ability to biodegrade crude oil and tolerate Cu²⁺ was isolated and purified. Identification results showed that the mentioned strain was most similar to Acinetobacter sp. and was designated as ZA-1. Based on the findings, using crude oil as the sole source of carbon and energy, compared to bacterial growth in nutrient broth, leads to a decrease in the strain's tolerance to Cu²⁺. Based on the results of ANOVA and the rate of crude oil biodegradation by strain ZA-1, it was determined that all factors studied except NH₄Cl concentration had a significant effect on the crude oil biodegradation process. The optimal conditions for crude oil biodegradation were determined to include pH=8, temperature=30 °C, salinity=30 g/L, and NH₄Cl concentration of 1.5 g/L. Strain ZA-1 was able to biodegrade 30.70% of crude oil. Considering the ability of the purified strain to degrade crude oil and tolerate Cu²⁺, the results of this study can be utilized in biological treatment processes for wastewater containing Cu²⁺ and contaminated with petroleum compounds.
