Currently, mechanism underlying mercury resistance and bioaccumulation of marine bacteria remains little understood. A marine bacterium Pseudomonas pseudoalcaligenes S1 is resistant to 120 mg/L Hg2+ with bioaccumulation capacity of 133.33 mg/g. Accordingly, Hg2+ resistance and bioaccumulation mechanism of S1 was investigated at molecular and cellular level. Annotation of S1 transcriptome reveals 772 differentially expressed genes, including Hg2+-relevant genes merT, merP and merA. Both merT and merP gene have three complete copies in S1 genome, while merA gene has only one. In order to evaluate the function of these Hg2+-relevant genes, three recombinant strains were constructed to express MerA (named as A), MerT/MerP (TP) and MerT/MerP/MerA (TPA), respectively. The results show that Hg2+ resistance of strain TP, TPA, and A are improved with minimum inhibition concentration (MIC) being 60 mg/L, 40 mg/L, and 20 mg/L, respectively compared to 2 mg/L of host strain. Strain TP and TPA exhibit enhanced Hg2+ bioaccumulation capacity, while strain A does not differ from the control. Their equilibrium Hg2+ bioaccumulation capacities are 110.48 mg/g, 94.49 mg/g, 83.76 mg/g and 82.29 mg/g, respectively. Summarily, different from most microorganisms that exhibit Hg2+ resistance by MerA-mediated mechanism, marine bacterium S1 achieves Hg2+ resistance and bioaccumulation capability via MerT/MerP-mediated strategy.

中文翻译：

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MerP / MerT介导的机制：一种抗汞和海洋细菌生物富集的方法。

目前，对汞抗性和海洋细菌生物富集的机制仍知之甚少。海洋细菌Pseudomonas pseudoalcaligenes S1对120 mg / L Hg2 +具有抗性，生物蓄积能力为133.33 mg / g。因此，在分子和细胞水平上研究了S1的Hg2 +抗性和生物积累机制。S1转录组的注释揭示了772个差异表达的基因，包括与Hg2 +相关的基因merT，merP和merA。merT和merP基因在S1基因组中均具有三个完整拷贝，而merA基因仅具有一个完整拷贝。为了评估这些Hg2 +相关基因的功能，构建了三种重组菌株分别表达MerA（命名为A），MerT / MerP（TP）和MerT / MerP / MerA（TPA）。结果表明，TP，TPA，与2 mg / L的宿主菌株相比，A和A的最低抑菌浓度（MIC）分别提高了60 mg / L，40 mg / L和20 mg / L。菌株TP和TPA表现出增强的Hg2 +生物蓄积能力，而菌株A与对照无差异。它们的平衡Hg2 +生物蓄积能力分别为110.48 mg / g，94.49 mg / g，83.76 mg / g和82.29 mg / g。总之，与大多数通过MerA介导的机制表现出对Hg2 +的抗性的微生物不同，海洋细菌S1通过MerT / MerP介导的策略实现了对Hg2 +的抗性和生物蓄积能力。它们的平衡Hg2 +生物蓄积能力分别为110.48 mg / g，94.49 mg / g，83.76 mg / g和82.29 mg / g。总之，与大多数通过MerA介导的机制表现出对Hg2 +的抗性的微生物不同，海洋细菌S1通过MerT / MerP介导的策略实现了对Hg2 +的抗性和生物蓄积能力。它们的平衡Hg2 +生物蓄积能力分别为110.48 mg / g，94.49 mg / g，83.76 mg / g和82.29 mg / g。总之，与大多数通过MerA介导的机制表现出对Hg2 +的抗性的微生物不同，海洋细菌S1通过MerT / MerP介导的策略实现了对Hg2 +的抗性和生物蓄积能力。