Studies On Degradation Of Oxytetracycline And Adsorption Of The Metal Cadmium By Phanerochaete Chrysosporium

With the development of modern industry, heavy metals are increasinglydischarged into the ecological system. And large doses of antibiotics used in thetreatment of human and animal diseases are also released into the environment.Antibiotics and heavy metals have persistent and cumulative characteristics, forminga permanent contamination to the environment, and causing serious pollution toatmosphere, water and soil. Biological treatment technology has gained wideattention of many researchers for its low consumption, high efficiency, convenientand reliable process operation management, no secondary pollution and othersignificant advantages. Because of its unique biodegradation to xenobiotics andbiosorption ability to heavy metals, Phanerochaete chrysosporium (P.chrysosporium) has been recognized as an effective bioremediation agent.This paper studies the degradation of oxytetracycline(OTC) by immobilizationand non-immobilized P. chrysosporium. The degradation and enzyme activity of theformer were significantly higher than the free state of fungi. OTC degradation rateby immobilized and non-immobilized Phanerochaete chrysosporium were92.44%and67.63%under its concentration of200mg/L, respectively. Manganese peroxidaseactivities of two samples were527.40U/L,73.90U/L, respectively, reaching amaximum value under oxytetracycline concentration of70mg/L. Lignin peroxidaseactivities of two samples were0.384U/L,0.204U/L, respectively, reaching amaximum value under oxytetracycline concentration of70mg/L. Manganeseperoxidase plays a key role in the degradation of oxytetracycline by Phanerochaetechrysosporium.The potential application of P. chrysosporium strain to treat wastewater thatpolluted by cadmium and OTC simultaneously was studied. During the test, theeffects of pH, initial cadmium concentration and initial OTC concentration wereanalyzed, respectively. The treatment efficiencies were pH dependent, and theoptimal pH for simultaneous cadmium adsorption and OTC degradation by P.chrysosporium was5.0, under an initial cadmium concentration of10mg L-1and aninitial OTC concentration of50mg L-1. The treatment efficiencies were dependenton the initial concentration of cadmium. The increase of initial cadmiumconcentration, ranging from5to10mg L-1, was helpful for both cadmium removaland OTC degradation by P. chrysosporium at the initial OTC concentration of50mg L-1. The treatment efficiencies were initial OTC concentration dependent, and aninitial OTC concentration of100mg L-1was optimum for cadmium removal andOTC degradation, under an initial cadmium concentration of50mg L-1. The surfacecharacteristics were studied by scanning electron microscopy. Experiments showthat the concentrations of cadmium or OTC increased properly would improve theactivity of the enzyme, but exceeding a certain limit, the enzyme activity decreasedwith increasing the concentration.