Rhodococcus ruber KE1 augmented phytoremediation of crude oil contamination using Lolium perenne and Festuca rubra rubra

Phytoremediation is an eco-friendly technique for hydrocarbon bioremoval. Phytoremediation efficiency can be enhanced through the cooperation of plants and crude oil degrading bacteria. This study was aimed to select crude oil tolerant grasses and clarify the bioremoval efficiency of R.ruber KE1-augmented phytoremediation. For this purpose, the resistance of Festuca rubra rubra, Festucarubra commutate, Lolium perenne, and Poa pratensis to crude oil was evaluated. Further, the supportive and augmenting role of R.ruber KE1 treatment on the morphological and biochemical properties of these grasses and crude oil phytoremediation was assessed. According to those results, Festuca rubra rubraand L. perenne were selected as more crude oil resistant grasses. R.ruber KE1 was able to significantly enhance its growth parameters (radicle, root, and shoot length) in the presence of crude oil. Results showed the most applied concentration of crude oil (5% w/w) inhibited Festuca rubra rubra growth while R.ruber KE1 treatment improved Festuca rubra rubra growth (P<0.05). A combination of R.ruber KE1 with L. perenne or Festuca rubra rubra resulted in a higherdegradation rate of >70% in all applied concentrations of crude oil after 40 days.Also, R.ruber KE1 treatment enhanced biodegrading of insoluble (36%→1.82%)and soluble (53.86%→14.52%) compounds of crude oil. R.ruber KE1-augmentedphytoremediation could be a promising approach to degrade recalcitranthydrocarbon pollutants and remediate contaminated soils.