Abstract
A polycyclic aromatic hydrocarbon (PAH)-degrading microbe was isolated and the effect of Pb(II) on the degradation of phenanthrene (PHE) by this microbe was studied in this research. The changes in the metabolism, protein content, enzyme activity and PHE degradation induced by Pb(II) were investigated to elucidate the effect of Pb(II) on the degradation of PHE. The protein content, catechol 2,3-dioxygenase activity and phenanthrene-degrading ability of the enzymes were all enhanced at low concentrations of Pb(II) (below 50 mg L-1) but decreased at relatively higher concentrations (100 to 300 mg L-1) of Pb(II). These results indicate that the presence of Pb(II) is relevant to enzymatic changes in this PAH-biodegrading microbe: it helps the process of PHE biodegradation at low concentrations, but impairs PHE biodegradation at excessive concentrations.