The EmhABC efflux pump in Pseudomonas fluorescens LP6a is involved in naphthalene tolerance but not efflux
The EmhABC efflux pump in Pseudomonas fluorescens LP6a is involved in naphthalene tolerance but not efflux
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DOI：
10.1007/s00253-012-4373-9
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发表时间：
2013-03-01
影响因子：
5
通讯作者：
Foght, Julia M.
中科院分区：
文献类型：
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作者：
Adebusuyi, Abigail A.;Foght, Julia M.
荧光假单胞菌 LP6a 中的 EmhABC 外排泵可排出多环芳烃 (PAH)，例如菲和蒽，但不排出萘。我们之前表明 EmhABC 的存在降低了菲生物降解的效率。在这项研究中，我们确定了荧光假单胞菌 LP6a 对萘的耐受性是否是 EmhABC 外排泵的函数，以及它的存在如何影响萘生物降解的效率。生长、膜脂肪酸 (FA) 组成和细胞形态表明 5 mmol L-1 萘对荧光假单胞菌 LP6a 菌株有抑制作用。 EmhABC 存在时，萘的有害作用被抑制，这表明，尽管 EmhABC 不流出萘，但该流出泵参与萘毒性的耐受。缺乏 EmhB 外排泵的 LP6a 突变体无法将顺式不饱和 FA 转化为环丙烷 FA，这表明萘干扰环丙烷 FA 的形成，并支持 EmhABC 参与荧光假单胞菌 LP6a 菌株中 FA 周转的提议。 EmhABC 外排泵提高了菌株 LP6a 中萘代谢的效率，这可能使得萘外排变得不必要。因此，碳氢化合物外排泵的活性可能是选择用于 PAH 生物修复或生物催化的菌株时需要考虑的重要因素。
The EmhABC efflux pump in Pseudomonas fluorescens LP6a effluxes polycyclic aromatic hydrocarbons (PAHs) such as phenanthrene and anthracene but not naphthalene. We previously showed that the presence of EmhABC decreased the efficiency of phenanthrene biodegradation. In this study, we determined whether P. fluorescens LP6a tolerance to naphthalene is a function of the EmhABC efflux pump and how its presence affects the efficiency of naphthalene biodegradation. Growth, membrane fatty acid (FA) composition, and cell morphology showed that 5-mmol L-1 naphthalene is inhibitory to P. fluorescens LP6a strains. The deleterious effect of naphthalene is suppressed in the presence of EmhABC, which suggests that, although naphthalene is not effluxed by EmhABC, this efflux pump is involved in tolerance of naphthalene toxicity. LP6a mutants lacking the EmhB efflux pump were unable to convert cis-unsaturated FAs to cyclopropane FAs, indicating that naphthalene interferes with the formation of cyclopropane FAs and supporting the proposal that EmhABC is involved in FA turnover in P. fluorescens LP6a strains. The EmhABC efflux pump increases the efficiency of naphthalene metabolism in strain LP6a, which may make naphthalene efflux unnecessary. Thus, the activity of hydrocarbon efflux pumps may be an important factor to consider when selecting bacterial strains for bioremediation or biocatalysis of PAHs.