Kinetics and metabolic versatility of highly tolerant phenol degrading Alcaligenes strain TW1

A bacterium that could completely metabolize phenol in batch culture supplied with up to 1200 mg phenol l(-1) at room temperature (25 degrees C) was isolated from the activated sludge of the industrial wastewater treatment plant of a Coke company (Cairo, Egypt). Morphological and physiological characterization showed strain TW1 was a motile, strictly aerobic, gram negative and short-rod occurring singly or in clusters. Partial 16S rRNA gene sequence analysis revealed strain TW1 belonged to the beta group of Proteobacteria, showing 100% identity to Alcaligenes SCTI. Strain TW1 aerobically grew on a number of monocyclic aromatic compounds (hydroquinone, catechol and o-cresol) as well as polycyclic aromatic compounds (pyrene, phenanthrene and naphthalene). The growth of Alcaligenes TW1 on phenol as sole carbon and energy source (25 degrees C) was well described by the Haldane kinetics model with a maximal specific growth rate of 0.58 h(-1), a half-saturation constant of 10 mg l(-1), and a substrate inhibition constant of 152-550 mg l(-1). The biomass yield coefficient ranged from 0.55 to 0.64 mg dry cell mass/mg phenol. Due to its high tolerance to phenol and high metabolic versatility, Alcaligenes sp. TW1 is considered an excellent candidate for the biotreatment of high strength phenol-laden industrial wastewaters.