Isolation and Characterization of Two Hydroxylated Aromatic Sulfonate-Assimilating Bacterial Strains, Cupriavidus basilensis PSY7 and Delftia lacustris HQS1, from Activated Sludge

Abstract

 Aromatic sulfonates (ASs) form one class of the major pollutants in wastewaters and natural waters and they are generally recalcitrant to biodegradation. Photodegradation and ozone treatment of ASs are effective for the removal, but tend to accumulate hydroxylated aromatic intermediates such as p-phenolsulfonate (PS) and hydroquinone sulfonate (HQS). To understand the possibility of the biodegradation of such compounds, one PS-assimilating bacterium and one HQS-assimilating bacterium were isolated from activated sludge and named PSY7 and HQS1, respectively. Strain PSY7 could degrade 1 mM PS in 30 h and grow on it, while strain HQS1 was also able to assimilate 1 mM HQS in 48 h. Genetic analysis and biochemical/physiological tests suggest that strains PSY7 and HQS1 belong to Cupriavidus basilensis and Delftia lacustris, respectively. As strain HQS1 could degrade both of PS and HQS, its biodegradation was further studied. Gene disruption study based on the genome sequence revealed that a gene (genA) necessary for the ring-cleavage of gentisate, which is very close to HQS in chemical structure, is involved in the HQS degradation. These information may contribute to the complete and efficient degradation of ASs.