铜绿假单胞菌胞外液对菲的降解特性研究

Degradation of phenanthrene through the cell-free extracellular fluid of P. aeruginosa NY3

以铜绿假单胞菌NY3为受试菌株,通过检测降解率、中间产物、可生化性及降解过程中自由基等指标,研究了铜绿假单胞菌胞外液对菲的降解特性及机理。结果表明,NY3菌胞外液具有一定的菲降解能力,72 h内降解率可达46.13%。通过中间产物鉴定结果可知,NY3菌胞外液可将含3个苯环的菲逐步降解为邻苯二甲酸酯、苯基乳酸、戊二酸等苯环减少或者无苯环的中间产物,表明该降解是一个逐步氧化的过程。这种胞外液对菲的初步降解,提高了菲的可生化性,可促进NY3菌细胞对其进一步代谢。对降解机理的初步探索发现,NY3菌胞外液中的吩嗪类物质,可通过自由基途径参与菲的降解。综合上述结果可知,铜绿假单胞菌胞外液可通过吩嗪类物质参与的自由基途径降解胞外液中的部分菲,增加胞外液中菲的可生化性,从而加速菲的生物降解过程。该研究结果可为全面了解铜绿假单胞菌降解污染物的路径及机理提供理论指导。

This paper is aimed at making an investigation of the degradation and its mechanism of phenanthrene through the examination of the cell-free extracellular fluid of P. aeruginosa.And,for such a research purpose,we have chosen P. aeruginosa NY3 as the strain under examination whereas the degradation efficiency,the intermediates,the bioavailability and the reactive oxygen species( ROS) are to be measured to demonstrate the degradation procedure from the various aspects. The results of the degradation experiments we have done demonstrate that the phenanthrene in the sewage can be degraded by the cell-free extracellular fluid of P. aeruginosas NY3,in which,the removal efficiency of phenanthrene can be made to reach up to 46. 13%,if,or when,the degradation process can be extended or prolonged to 72 h. And, furthermore, the total organic carbon( TOC) accompanied can also be made to decrease by 21. 58%.And,in addition,the intermediates identified from the results of GC-MS experiments also suggest that metabolites with less or no rings in its formula,such as,phthalate,3-phenyllactic acid and glutaric acid,can all be produced. Thus,it can be seen that it is possible for the phenanthrene to be oxidized by the cell-free extracellular fluid of P. aeruginosa NY3 progressively step by step,and eventually converted into carbon dioxide and water.And,what is more,the bio-availability measurement of hydrophobic phenanthrene also suggests that the oxidation of phenanthrene by the cell-free extracellular fluid of P. aeruginosa NY3 can help to heighten its uptake efficiency by the cell of strain NY3,which can in turn promote the metabolism of phenanthrene by the cells of P. aeruginosa NY3. And,consequently,it would be possible to result in a virtuous circle in the degradation system of phenanthrene by P. aeruginosa NY3. And,so,tentative exploration of the mechanism helps us to disclose that there have been existing lots of superoxide anion radicals in the extracellular fluid of P. aeruginosa NY3. This may suggest that free radicals ought to be involved in the procedure of phenanthrene degradation.And,therefore,it would be possible for us to conclude that,despite the degradation effect of enzyme,the extracellular fluid of P. aeruginosa can help to degrade phenanthrene through a pathway via the free radicals,and subsequently promote its biodegradation efficiency by increasing the uptake efficiency with the cells of P. aeruginosa NY3. And,consequently,the results we have gained are qualified enough to provide an important theoretical guidance for thorough understanding of the mechanism of the pollutants degraded by P. aeruginosa.