Research On Antibiotics And Heavy Metal Bioaccumulation Characteristics And Dual Resistance Mechanism Of Phanerochaete Chrysosporium

The combined pollution phenomenon is prevalent in the environment, it often can not beexplained by a single contaminated mechanism and evaluation criterias developed based ona single contamination can not be a true reflection of environmental quality. Therefore, theco-pollution has become one of the important and urgent research points of environmentalscience and environmental management. Heavy-metals and antibiotics are two typical type ofenvironmental pollutants, which can often be detected simultaneously in the environment. Asis known, the two may complex with each other and result in more serious pollution. Thispaper anlyzed the oxytetracycline degradation, Pb(II) and Cd(II) bioaccumulation, andresistance mechanisms of Phanerochaete chrysosporium cultivated under oxytetracycline,Pb(II) and Cd(II) co-polluted environment.Established a method to detect oxytetracycline. The optimal conditions for liquidchromatography was using methanol:0.1%phosphoric acid (60:40) as the mobile phase, flowrate was set to0.7mL/min, injection volume of20μL, column temperature was35℃.The factors that affected the growth, degradation and bioaccumulation efficiency byPhanerochaete chrysosporium were thoroughly investigated, such as pH value, temperture,initial oxytetracycline, Pb(II) and Cd(II) concentration, and co-ions in the liquid medium. Theoptimal condition occurred at pH=4.5and35℃, the growth, degradation and bioaccumulationefficiency all reached peak value. Oxytetracycline at low concentration could promote thegrowth, but an opposite result was obtained with a further increase in the initial cadmiumdegradation, Pb(II) and Cd(II) concentration. Co-ions may compete adsorption sites with eachother,resulting in inhibition of enrichment. In addition, the changes of micrographs fromscanning electron micrograph showed that there were difference between mechanisms ofoxytetracycline degradation and heavy-metal enrichment.The resistant mechanism of oxytetracycline, Pb(II) and Cd(II) by Phanerochaetechrysosporium were studied. The results showed that the existence of oxtetracycline andheavy metals could have effects on activities and contents of extracellular and intracellularenzyme. Oxytetracycline and Pb(II) could enhance LiP activity, but Cd(II) played a oppsiterole. As for activity of MnP, most heavy metals could inhibit its activity including Pb(II) andCd(II), oxytetracycline could also promote MnP activity. Under the same condition, theactivity change of MnP was higher than LiP. Further analysed the MnP gene relativequantitative expression, it showed that gene MnP1and MnP2may regulate the process ofoxytetracycline degradation in varying degrees or may easily be damaged by Pb(II) and Cd(II), MnP2may control the production of these proteins related to Pb(II) and Cd(II) complextion.Besides,MnP activity changes and changes in gene expression have no clear agreement, notthe high levels of MnP gene expression would enable high MnP activity. The activities ofSOD, CAT and content of MAD in the cells of Phanerochaete chrysosporium were alsodetermined, all three pollutants may damage the strain, and the strian colud develop a resistantmechanism to protect themselves.