Adsorption of halogenated aromatic pollutants by a protein released from Bacillus pumilus

Previous studies of the biosorption of halogenated aromatic pollutants (HAPs) have focused on the sorption of these compounds by cell bodies. However, in this study we investigated the adsorption of HAPs by biocompounds released from a bacterium, Bacillus pumilus. When B. pumilus was exposed to high temperature, it released a protein and carbohydrates, exclusively. After determining experimental conditions using 1,2,3,4-tetrachlorinated dibenzofuran (1,2,3,4-TCDF), the adsorption characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), chlorinated benzenes, and chlorinated naphthalenes were investigated. These HAPs were adsorbed considerably not only by cells but also by the released protein. In general, highly chlorinated congeners were adsorbed to a greater extent on the protein than lowly chlorinated ones, and the amount adsorbed differed between isomers. The present results are consistent with adsorption occurring via a passive physico-chemical mechanism. Finally, the importance of biocompounds released or excreted from microorganisms for the removal of HAPs is discussed.