Separation,Purification and Characterization of Three Endo-polygalacturonases from a Newly Isolated Penicillum oxalicum

Three endo-polygalacturonases (endoPGs) from a newly isolated Penicillum oxalicum (CGMCC 0907) capable of utilizing waste biomass as growth substrate were separated and purified to homogeneity by ultra-filtration, affinity adsorption chromatography, CM-cellulose column chromatography, and Sephadex G-100 gel filtration chromatography with the overall yield of 64.5% from the crude enzyme. The specific activities and recovery rates of endoPG-1, endoPG-2 and endoPG-3 were 1120 U/mg and 21.6%, 1350 U/mg and 25.9%, and 1560 U/mg and 17.0%, respectively. The three purified endoPGs had a close molecular weight to 41 kDa as estimated by SDS-PAGE. The optimum temperature and pH for the function of them were 65℃ and 5.0, 55℃ and 5.0, 50℃ and 5.5, respectively. Their pI and Km values were 5.9 and 0.78 mg/mL, 6.0 and 1.2 mg/mL, and 6.1 and 2.0 mg/mL, respectively.     

不同芘处理对土壤氨氧化微生物的影响

[目的]研究不同芘处理对土壤氨氧化微生物的影响.[方法]采用α-萘胺显色法测定了土壤硝化潜势(PNR),实时定量PCR方法测定了amoA基因拷贝数.[结果]芘和PNR的剂量-效应关系满足四参数的Logistic曲线,各处理土壤PNR的EC<,50>分布在70～100μg/g范围内,且随处理时间延长而增大,表明土壤微生态群落对芘产生了一定的适应或抗性;芘的急性毒性表现在中高浓度芘处理下,持久性毒性在各浓度处理下均有明显表现;芘的存在在短期内并不能改变氨氧化微生物的群落丰度及基因拷贝数.[结论]中等芘浓度范围(70～100μg/g)是PNR较敏感的浓度段,芘对土壤PNR的影响可能是对氨氧化过程中关键酶AMO的竞争性抑制作用.