Effect of Cadmium on Biodegradation of Nonylphenol by Pseudomonas aeruginosa

Abstract

The influence of Cd on the degradation of nonylphenol (NP) by P.aeruginosa SH1 was investigated in this study.The investigation revealed that biomass of the strain was significantly declined with the increase of Cd2+ concentration.The biomass was declined by 27.1% in the presence of 10 mg·L-1Cd2+ after 24 h.The addition of Cd2+ had a great influence on adsorption of NP by the strain.As for the effect of living stain,adsorption by P.aeruginosa SH1 cells was stimulated at low concentrations of Cd2+(0.5 mg·L-1),while inhibited at higher levels (≥5 mg·L-1).As for inactivation of microbes,adsorption by cells was stimulated at higher concentrations,but was only slightly influenced at low levels.The results showed that the intracellular enzymes had much greater degradation rate than the living cells.Different concentrations of Cd2+ had different effects on bacteria and intracellular enzyme degradation of NP separately.The degradation efficiency when using intracellular enzymes and bacteria was inhibited at higher levels of Cd2+ and the intracellular enzyme inhibition was more significant.Degradation by cells was stimulated at low concentrations of Cd2+,but no significant impact was found on that by intracellular enzymes.The degradation process of NP by intracellular enzymes of the strain conformed to the first-order kinetic model.The highest reaction rate was achieved when the concentrations of Cd2+ was 0.5 mg·L-1 and the half-life of this substrate was 5.5 h.However,the degradation process of NP by the strain did not conform to the first-order kinetic model.