表面活性剂Burkholderia xenovorans LB400体系对低氯代PCBs的好氧强化降解

增强多氯联苯(PCBs)的水溶性是强化PCBs微生物降解的主要控制因素之一,本研究选取了PCB5(2,3-CB)和PCB31(2,4’,5-CB)作为低氯代PCBs的典型代表,以曲拉通100(TX-100)、吐温80(Tween 80)、鼠李糖脂粗提物(RL crude)3种表面活性剂和β-环糊精(HPCD)联合Burkholderia xenovorans LB400构建PCBs好氧降解体系,测试了它们对PCB5和PCB31的溶出率及微生物生长的影响.结果表明,TX-100(CMC=194 mg·L-1)、Tween 80(CMC=13.1 mg·L-1)、RL crude(CMC=50mg·L-1)浓度在1~7 CMC时和HPCD浓度在500~1500 mg·L-1时对PCB5和PCB31溶出率分别达到54.7%~100%、59.8%~100%;10.5%~40.8%、6.8%~31.6%;10.3%~19.9%、3.3%~11.6%和19.5%~34.2%、4.2%~10.7%.TX-100浓度在1~7 CMC时对B.xenovorans LB400生长的抑制率达到30.3%~45.8%,而Tween 80浓度在0.1~1 CMC时对其生长的抑制率为10.0%~15.4%;RL crude本身能作为底物促进LB400的生长,而HPCD对其生长无明显影响.B.xenovorans LB400对PCB31(5 mg·L-1)的降解效率在添加表面活性剂后有不同程度的提高:TX-100,23.7%~65.5%;Tween80,14.6%~44.3%;RL crude,9.6%~27.2%;HPCD,15.3%~20.7%;而表面活性剂对PCB5(10 mg·L-1)的降解效率则无明显影响.表面活性剂主要通过增大溶液中PCBs-表面活性剂的胶束浓度来提高LB400对PCBs的降解效率,在水溶液培养体系中当设置TX-100和Tween 80浓度分别在1和7 CMC时,PCB31的降解效率达到100%和81.7%,而此时B.xenovorans LB400生长的抑制率为30.3%和5.4%.

Enhanced Aerobic Degradation of Low Chlorinated Biphenyls by Constructing Surfactants Burkholderia xenovorans LB400 Based System

It has been proposed that the increasing of water solubility of PCBs can enhance the biodegradation efficiency. The biodegradation system of PCBs by Burkholderia xenovorans LB400 in the presence of different surfactants, namely TX-100, Tween 80, RL crude and HPCD were established to investigate the effect of surfactants on the biodegradation of hydrophobic organic compounds. The results indicated that the water solubility ratios of PCB5 and PCB31 were 54.7%-100%, 59.8%-100%; 10.5%-40.8%, 6.8%-31.6%; 10.3%-19.9%, 3.3%-11.6% and 19.5%-34.2%, 4.2%-10.7%, which were accordingly enhanced by TX-100 (CMC=194 mg ·L^-1), Tween 80 (CMC=13.1 mg ·L^-1), and RL crude (CMC=50 mg ·L^-1) with concentrations of 1-7 CMC, respectively and HPCD with concentrations of 500-1500 mg ·L^-1. Moreover, the growth inhibition ratio of B. xenovorans LB400 was 30.3%-45.8% with TX-100 concentration of 1-7 CMC, while it was 10.0%-15.4% for Tween 80 with concentration of 0.1-1 CMC; RL crude could boost the growth of strain LB400 as substrate while HPCD exerted no impact on it. The addition of surfactants can improve the biodegradation ratios of PCB31 (5 mg ·L^-1) by 23.7%-65.5% for TX-100, 14.6%-44.3% for Tween 80, 9.6%-27.2% for RL crude and 15.3%-20.7% for HPCD depending on the surfactant concentrations, while it had minor effects on the biodegradation ratios of PCB5 (10 mg ·L^-1). It is concluded that the promoting effects of surfactant on PCBs biodegradation are mainly due to the increased concentrations of PCBs-surfactant micelles in aqueous solution and when TX-100 and Tween 80 concentrations are set as 1 and 7 CMC, the biodegradation ratios of PCB31 can achieve 100% and 81.7%, while the growth inhibition ratios of B. xenovorans LB400 are 30.3% and 5.4%, respectively.