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?degrees C and 35?degrees 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 (mu max) of 0.1102 hr-1, a half-saturation constant (Ks) of 99.03?mg l-1 or 1.05?mmol l-1, and a substrate inhibition constant (Ki) of 354?mg l-1 or 3.76?mmol l-1. Aside from phenol, the strain could utilize diesel, 2,4-dinitrophenol and ?-cresol as carbon sources for growth. Strain AQ5NOL 2 exhibited inhibition of phenol degradation by Zn2+, Cu2+, Cr6+, Ag+ and Hg2+ at 1?mg l(-1).