Uptake and active efflux of polycyclic aromatic hydrocarbons by Pseudomonas fluorescens LP6a
Uptake and active efflux of polycyclic aromatic hydrocarbons by Pseudomonas fluorescens LP6a
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DOI：
10.1128/aem.66.12.5387-5392.2000
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发表时间：
2000-12-01
影响因子：
4.4
通讯作者：
Gray, MR
中科院分区：
文献类型：
--
作者：
Bugg, T;Foght, JM;Gray, MR
通过抑制膜转运和测定细胞摄取量的变化，研究了PAM降解菌荧光假单胞菌（PseudomonasfluorescensLP 6a）对多环芳烃（PAHs）的转运机制。使用了三种培养物：携带用于PAH降解的质粒的野生型LP 6a、缺乏用于PAM降解的途径中的第一酶的转座子突变体、以及没有质粒的治愈菌株。将洗涤的细胞与放射性标记的PAH的水溶液混合;然后通过离心除去细胞，并测量上清液和细胞沉淀中PAM的浓度。加入膜转运抑制剂（叠氮化物、氰化物或羰基氰间氯苯腙）后，沉淀和上清液浓度的变化表明了主动转运的作用。这些数据是一致的存在两个相互冲突的运输机制：被动扩散和能量驱动的外排系统，以运输多环芳烃的细胞吸收。外排机制是染色体编码的。在所用的测试条件下，荧光假单胞菌LP 6a对菲的吸收和外排均不饱和。外排机制表现出选择性，因为菲，蒽，荧蒽被运输出细胞，但萘不是。
The mechanism of transport of polycyclic aromatic hydrocarbons (PAHs) by Pseudomonas fluorescens LP6a, a PAM-degrading bacterium, was studied by inhibiting membrane transport and measuring the resulting change in cellular uptake. Three cultures were used: wild-type LP6a which carried a plasmid for PAH degradation, a transposon mutant lacking the first enzyme in the pathway for PAM degradation, and a cured strain without the plasmid. Washed cells were mixed with aqueous solutions of radiolabelled PAH; then the cells were removed by centrifugation, and the concentrations of PAM in the supernatant and the cell pellet were measured. The change in the pellet and supernatant concentrations after inhibitors of membrane transport (azide, cyanide, or carbonyl cyanide m-chlorophenyl hydrazone) were added indicated the role of active transport. The data were consistent with the presence of two conflicting transport mechanisms: uptake by passive diffusion and an energy-driven efflux system to transport PAHs out of the cell. The efflux mechanism was chromosomally encoded, Under the test conditions used, neither uptake nor efflux of phenanthrene by P, fluorescens LP6a was saturated. The efflux mechanism showed selectivity since phenanthrene, anthracene, and fluoranthene were transported out of the cell but naphthalene was not.