Isolation and characterization of a phenol-degrading bacterium from an industrial activated sludge

This paper reports the successful isolation and characterization of a new phenol-degrading bacterium, strain EDP3, from activated sludge. Strain EDP3 is a nonmotile, strictly aerobic, Gram-negative, and short-rod or coccobacillary bacterium, which occurs singly, in pairs, or in clusters. 16S rRNA gene sequence analysis revealed that strain EDP3 belonged to the gamma group of Proteobacteria, with a 97.0% identity to 16S rRNA gene sequences of Acinetobacter calcoaceticus. Strain EDP3 could aerobically grow on a number of aromatic compounds, such as phenol, sodium benzoate, p-hydroxybenzoate, phenylacetate, benzene, ethylbenzene, benzylalcohol, and so on. In particular, it could mineralize up to 1,000 mg l(-1) phenol at room temperature (25 degrees C). The growth kinetics of strain EDP3 on phenol as a sole carbon and energy source at 25 degrees C can be described using the Haldane equation. It has a maximal specific growth rate (mu(max)) of 0.28 h(-1), a half-saturation constant (K-S) of 1,167.1 mg l(-1), and a substrate inhibition constant (K-i) of 58.5 mg l(-1). Values of yield coefficient (Y-X/S) are between 0.4 and 0.6 mg dry cell (mg phenol)(-1). Strain EDP3 has high tolerance to the toxicity of phenol (up to 1,000 mg l(-1)). It therefore could be an excellent candidate for the biotreatment of high-strength phenol-containing industrial wastewaters and for the in situ bioremediation of phenol-contaminated soils.