1 Zhejiang Key Laboratory of Petrochemical Environmental Pollution Control, Zhejiang Ocean University, Zhoushan, P. R. China.
2 National & Local Joint Engineering Research Center of Harbor Oil & Gas Storage and Transportation Technology, Zhejiang Ocean University, Zhoushan, P. R. China.
3 Naval Medical Center of Chinese People's Liberation Army, Shanghai, P. R. China.
4 Department of Building, Civil and Environmental Engineering, Faculty of Engineering & Computer Sciences, Concordia University, Montreal, Quebec, Canada.

The tolerance and degradation characteristics of a marine oil-degrading strain Acinetobacter sp. Y9 were investigated in the presence of diesel oil and simulated radioactive nuclides (Mn²⁺, Co²⁺, Ni²⁺, Sr²⁺, Cs⁺) at varying concentrations, as well as exposure to ?-ray radiation (Co-60). The maximum tolerable concentrations for Co²⁺and Ni²⁺ were found to be 5 mg/l and 25 mg/l, respectively, while the tolerable concentrations for Mn²⁺, Sr²⁺, and Cs⁺ exceeded 400 mg/l, 1000 mg/l, and 1000 mg/l, respectively. A total of 0.4 Gy/h of ?-ray radiation (Co-60) did not significantly affect the growth of strain Y9. The presence of metal nuclides and ?-ray radiation primarily inhibited the production of outer membrane proteins while promoting the secretion of polysaccharides in strain Y9. Strain Y9 exhibited a notable capacity to degrade diesel oil under radiative conditions when exposed to the five individual radionuclides used in this study. Furthermore, the introduction of the radiation-resistant strain R1 significantly enhanced the diesel oil degradation efficiency of strain Y9 in the presence of a mixture of five nuclides, with the degradation efficiency increasing from 26.7% to 46.75%. Strain R1 demonstrated the ability to absorb a substantial amount of free nuclides, thereby creating favorable environmental conditions for the growth and degradation activity of strain Y9. PRACTITIONER POINTS: Investigate the tolerance mechanisms of strain Y9 to different nuclides and ?-ray irradiation. Examine the degradation characteristics of strain Y9 on diesel oil under the influence of nuclides and irradiation. In a single nuclide medium, strain Y9 exhibited a high degradation rate of 90.64% toward 1% diesel oil concentration. The addition of a radiation-resistant strain R1 can enhance the degradation efficiency of Y9 toward diesel oil.