Trans-membrane transport of fluoranthene by Rhodococcus sp. BAP-1 and optimization of uptake process

• A new strain was identified as Rhodococcus sp. BAP-1.
• Demonstrated the mechanism for fluoranthene travel across bacteria cell membrane.
• Transport dynamic combined with RSM to screen the significant variables.
• Plackett–Burman design was used to screen the significant variables.
• Box–Behnken design was employed to optimize the trans-membrane transport process.

The mechanism of transport of 14C-fluoranthene by Rhodococcus sp. BAP-1, a Gram-positive bacterium isolated from crude oil-polluted soil, was examined. Our finding demonstrated that the mechanism for fluoranthene travel across the cell membrane in Rhodococcus sp. BAP-1 requires energy. Meanwhile, the transport of fluoranthene involves concurrent catabolism of 14C, that leading to the generation of significant amount of 14CO2. Combined with trans-membrane transport dynamic and response surface methodology, a significant influence of temperature, pH and salinity on cellular uptake rate was screened by Plackett–Burman design. Then, Box–Behnken design was employed to optimize and enhanced the trans-membrane transport process. The results predicted by Box–Behnken design indicated that the maximum cellular uptake rate of fluoranthene could be achieve to 0.308 μmol min−1 mg−1·protein (observed) and 0.304 μmol min−1 mg−1·protein (predicted) when the initial temperature, pH and salinity were set at 20 °C, 9% and 1%, respectively.