HP-β-CD对不动杆菌降解高浓度硝基苯的影响

Effect of HP-β-CD on the biodegradation of nitrobenzene at high concentration by Acinetobacter sp.

研究了在不动杆菌降解高浓度硝基苯的过程中添加羟丙基-β-环糊精(HP-β-CD)对细菌生长、硝基苯的去除及中间产物的转化的影响.利用乙酸酐直接将硝基苯的降解样品酰基化,通过GC-MS分析定性出降解中间产物2 氨基苯酚.在适宜降解菌生长的400mg·L-1硝基苯初始浓度下,加入250和500mg·L-1HP-β-CD对生物量和硝基苯的降解基本无影响;当硝基苯初始浓度约为850mg·L-1时,加入HP-β-CD(>2000mg·L-1)显著促进了细菌的生长、硝基苯的降解和2-氨基苯酚的生物转化,并且促进程度与加入量成正比.这种促进主要是因为HP-β-CD的空腔对硝基苯和2-氨基苯酚的包合产生了脱毒的效果.当HP-β-CD的加入浓度分别为0,2000,4000mg·L-1时,降解菌对850mg·L-1硝基苯的降解都遵循一级反应动力学,降解速率常数由0 0077h-1分别增加到0 0089和0 0161h-1,当HP-β-CD的加入浓度为8000mg·L-1时,降解菌对850mg·L-1硝基苯的降解遵循零级反应动力学,其降解速率常数为16 1162mg·L-1·h-1.

The present study investigated the effect of Hydroxypropylβcyclodextrin (HPβCD) on the cell growth, removal of nitrobenzene and the transformation of intermediates during the biodegradation process of nitrobenzene at high concentration by Acinetobacter sp. 2aminophenol was identified as an intermediates using direct acetylation of biodegraded samples of nitrobenzene by acetic anhydride followed by GCMS analysis. When the initial concentration of nitrobenzene was about 400?mg·L-1 (optimal concentration for degrading bacteria to grow vigorously), HPβCD added at 250?mg·L-1 or 500?mg·L-1 had no effect on the biomass and the degradation of nitrobenzene. However, the addition of HPβCD at above 2000?mg·L-1, significantly enhanced the cell growth, the biodegradation of nitrobenzene and the transformation of intermediates when the initial concentration of nitrobenzene was about 850?mg·L-1. The promoting effect was increased proportionally with the dosage of HPβCD, which was mainly due to the detoxification ability of HPβCD through the formation inclusion complexes with nitrobenzene and 2aminophenol. The biodegradation kinetics of 850?mg·L-1 nitrobenzene followed firstorder reaction when HPβCD was added at 0, 2000, 4000?mg·L-1, and the kinetic constant was increased from 00077?h-1 to 00089 and 00161?h-1. However, when HPβCD was added at 8000?mg·L-1, the kinetics was changed to zeroorder reaction and the kinetic constant was 161162?mg·L-1·h-1. 