Effect Of Nanometer Magnesium Oxide On Phenol Degradation By Rhodococcus Rubber

Rhodococcus rubber is the phenol-specific degrading bacteria and can remove phenol significantly.However,the degradation process usually takes a long time.The key problem is how to improve the enzyme activity,reduce the degradation time,and cut down the cost.Some studies showed that the nanometer metal oxide could improve the activity and tolerance of microorganisms,as well as the metabolic efficiency for pollutants.In this experiment,the effect of nanometer magnesium oxide?N-MgO?on the degradation of phenol by Rhodococcus rubber was studied by orthogonal experiment,and then suitable condition for degradation was analysed.The mechanism of the degradation of phenol by N-MgO was studied,and the results should provide data for phenol microbial degradation.L₂₅?5⁶?orthogonal array was used to determine the influence degree of six factors,the result arranged was Rhodococcus rubber,N-MgO,temperature,pH,NaCl and phenol.When other factors in the appropriate conditions,the removal efficiency was improved with the addition of N-MgO at 100 mg/L.In this condition,the removal rate was 95.74%at 48 h,it was improved 1.25 times compared with negative control?76.46 %?,and the removal rate was the same to the negative control at 72 h.However,Rhodococcus rubber was inhibited totally and had no ability to degrade phenol in the condition with the higher concentration of N-MgO.The result also showed that N-MgO can promote the activities of catechol 1,2-dioxygenase?C12O?and catechol 2,3-dioxygenase?C23O?,especially to C23 O.The cleaving way of catechol changed from both ortho-cleavage and meta-cleavage to ortho-cleavage priority.The present of N-MgO not only improved the enzyme activity,but also changed the cleavage pathway of catechol.