Biodegradation of Aromatic Compounds by a Halophilic Archaeon Isolated from the Dead Sea

Abstract

It is well established that aromatic compounds can be readily degraded in aerobic environments within soils, sediments and waters with salinities up to and including that of seawater. However, little is known about their metabolism in hypersaline environments. There is a growing interest in the development and optimization of bioremediation processes to deal with environments with high salinity that are contaminated with aromatic compounds. Among prokaryotes, haloarchaea are a group of microorganisms living in hypersaline environments that may have a greater potential in degrading pollutants than previously assumed and can be considered as a good environmental tool for bioremediation. We enriched and isolated 10 halophilic archaea from Dead Sea water samples on the basis of their ability to grow on p-hydroxybenzoic acid (pHBA) as the sole carbon and energy source. All isolates showed identical total lipid profiles, but are metabolically very diverse. Strain L1, which is also capable of growth on benzoic acid (BA), was chosen for biodegradation kinetics determination. When grown in BA, strain L1 produced small amounts of a compound that co-chromatographed with gentisic acid, which accumulated in the medium. The same did not occur when pHBA was the growth substrate. A discussion on the possible metabolic pathways involved is included, and a preliminary characterization of strain L1 is presented.