Influence of chemical oxidant on degradation of benzo[a]pyrene metabolites by the bacterium-Zoogloea sp.

It is neither comprehensive nor appropriate that the bioremediation of a benzo[a]pyrene (BaP)-contaminated environment be assessed only by its high degradation extent because its metabolites' chemical structures are similar to the parent compound and maybe equally toxic. Therefore, further degradation of BaP metabolites is significant. Three methods, combining the <i>Zoogloea </i>sp. with potassium permanganate, combining the <i>Zoogloea </i>sp. with H₂O₂, <i>Zoogloea </i>sp. alone, were investigated to degrade cis-BP4,5-dihydrodiol and cis-BP7,8-dihydrodiol, which are the metabolites of BaP formed by bacterium-Zoogloea sp. Optimum parameters of degradation in the best method are that: of the three methods, coupling the Zoogloea sp. and KMnO₄ is the best; compared with cis-BP7,8-dihydrodiol, <i>cis</i>-BP4,5-dihydrodiol is the more liable to be accumulated in pure cultures; the degradation effect of the two metabolites is optimal when the initial concentration of KMnO₄ in the cultures is 0.05%; initial concentration of <i>cis</i>-BP4,5-dihydrodiol and <i>cis</i>-BP7,8-dihydrodiol is 4 mg L⁻¹, 8 mg L⁻¹, respectively; cometabolic substance is salicylic acid or sodium succinate. The degradation extent of <i>cis</i>-BP4,5-dihydrodiol and <i>cis</i>-BP7,8-dihydrodiol using combining the <i>Zoogloea </i>sp. and KMnO₄ reach 76.1% and 85.9% after 12 days of cultivation, respectively, which were more than twice compared with conventional method.<br />