Physiological cellular responses and adaptations of Rhodococcus erythropolis IBBPo1 to toxic organic solvents

A new Gram-positive bacterium, Rhodococcus erythropolis IBB_Po1 (KF059972.1) was isolated from a crude oil-contaminated soil sample by enrichment culture method. R. erythropolis IBB_Po1 was able to tolerate a wide range of toxic compounds, such as antibiotics (800–1000 μg/mL), synthetic surfactants (50–200 μg/mL), and organic solvents (40%–100%). R. erythropolis IBB_Po1 showed good tolerance to both alkanes (cyclohexane, n-hexane, n-decane) and aromatics (toluene, styrene, ethylbenzene) with logP_OW (logarithm of the partition coefficient of the solvent in octanol–water mixture) values between 2.64 and 5.98. However, alkanes were less toxic for R. erythropolis IBB_Po1 cells, compared with aromatics. The high organic solvent tolerance of R. erythropolis IBB_Po1 could be due to the presence in their large genome of some catabolic (alkB, alkB1, todC1, todM, xylM), transporter (HAE1) and trehalose-6-phosphate synthase (otsA1, KF059973.1) genes. Numerous and complex physiological cellular responses and adaptations involved in organic solvent tolerance were revealed in R. erythropolis IBB_Po1 cells exposed 1 and 24 hr to 1% organic solvents. R. erythropolis IBB_Po1 cells adapt to 1% organic solvents by changing surface hydrophobicity, morphology and their metabolic fingerprinting. Considerable modifications in otsA1 gene sequence were also observed in cells exposed to organic solvents (except ethylbenzene).