Isolation and characterization of a phenol‐degrading Rhodococcus sp. strain AQ5NOL 2 KCTC 11961BP

In this work, we report on the isolation of a phenol‐degrading Rhodococcus sp. with a high tolerance towards phenol. The isolate was identified as Rhodococcus sp. strain AQ5NOL 2, based on 16S rDNA analysis. The strain degraded phenol using the meta pathway, a trait shared by many phenol‐degraders. In addition to phenol biodegradation, the strain was also capable of degrading diesel. Strain AQ5NOL 2 exhibited a broad optimum temperature for growth on phenol at between 20 °C and 35 °C. The best nitrogen sources were ammonium sulphate, glycine or phenylalanine, followed by proline, nitrate, leucine, and alanine (in decreasing efficiency). Strain AQ5NOL 2 showed a high tolerance and degradation capacity of phenol, for it was able to register growth in the presence of 2000 mg l −1 phenol. The growth of this strain on phenol as sole carbon and energy source were modeled using Haldane kinetics with a maximal specific growth rate ( μ max ) of 0.1102 hr −1 , a half‐saturation constant ( K s ) of 99.03 mg l −1 or 1.05 mmol l −1 , and a substrate inhibition constant ( K i ) of 354 mg l −1 or 3.76 mmol l −1 . Aside from phenol, the strain could utilize diesel, 2,4‐dinitrophenol and ρ ‐cresol as carbon sources for growth. Strain AQ5NOL 2 exhibited inhibition of phenol degradation by Zn 2+ , Cu 2+ , Cr 6+ , Ag + and Hg 2+ at 1 mg l −1 .