Screening Of Highly Efficient Degradation Bacteria Of P-Toluenesulfonic Acid And Its Degradation Characteristics And Degradation Kinetics

P-toluenesulfonic acid(p-TSA)is an important chemical raw materials and widely used in industry production.A large number of p-TSA wastewater discharged would pose a serious threat to human health and the environment.In this paper,a highly efficient p-TSA degrading strain was isolated from the wastewater treatment pool of a pharmaceutical factory by enrichment and separation technology.It could utilize p-TSA as the sole carbon source for growth and was designated as Y-2.The strain could completely degraded 200mg/L p-TSA within 16h.The strain was Gram-negative bacteria and preliminary identified as Pseudomonas stutzeri according to its physiological and biochemical properties and 16s rRNA gene sequence analysis.Strain Y-2 grew well in LB medium.The growth of the strain was in the lag phase in initial 0-5h,after 5h,it entering into the logarithmic growth phase,in 16-25h,strain staying in the stable growth period and after 25h,strain being gradually declined.The optimum temperature and pH for the growth of strain Y-2 were 30? and pH=7.0?8.0,respectively.The strain Y-2 is strictly aerobic bacteria and ventilation is favorable for strains growth.The concentration of NaCl also impact the growth of strain.The strain Y-2 grew well at a NaCl concentration of 5-15g/L.The optimum NaCl concentration was lOg/L.The strain Y-2 could utilize glucose,fructose and maltose,but incapable of using sucrose,mannitol,xylose.It could also use peptone,ammonium sulfate and ammonium but not urea.The strain Y-2 could completely degrade 200mg/L p-TSA in 16h.The optimum temperature and pH for p-TSA degradation by strain Y-2 were 30°C and pH=7.0,respectively.The aeration condition will improve the degradation of p-TSA.In inoculum range of 0.1%-2%,increase the inoculum amount can significantly increase the p-TSA degradation rate.But when the inocolim amount is more than 4%,the degradation rate no longer increased.Increasing the initial concentration of p-TSA,the lag phase of strain Y-2 longer and longer,but the strain is capable of completely degrading 500mg/L of p-TSA within 40h.Adding 200mg/L glucose as an additional carbon source promoted the degradation of p-TSA and reduced the degradation time.The metabolites during the degradation were detected by LC-MS,and the major metabolites found to be 4-sulfobenzoic acid,p-Hydroxybenzenesulfonic acid,hydroquinone,maleic acid and oxalic acid.The pathway of p-TSA biodegradation by strain Y-2 was proposed:The first step of the biodegradation pathway is side-chain oxidation of methyl groups to form p-sulfobenzoic acid.The next step is decarboxylation of p-sulfobenzoic acid to form p-phenolsulfonic acid.The third step is desulfonation of p-phenolsulfonic acid to form hydroquinone.Further degradation reactions of the aromatic intermediates hydroquinone yield to maleic acid and Oxalic aci.Finally,maleic acid and Oxalic acid is completely mineralised.The p-TSA degradation kinetics were fitted by Lawrence-Mc Carty equation.Kinetic parameters were obtained:Vmax = 46.95 mg/L/h,Ks = 59.09 mg/L.when the concentration of p-TSA was much higher than 46.95mg/L,the p-TSA degradation consistent with zero order kinetics.When the p-TSA concentration is much lower than 46.95mg/L,the p-TSA degradation by strain Y-2 consistent with first order kinetics.The higher the substrate is,the faster the degradation rate will be.