作为冷藏水产品中常见的条件致病菌，铜绿假单胞菌可引起严重甚至致死性感染。本课题前期研究发现姜黄素介导的光动力作用高效灭活铜绿假单胞菌过程中，可诱导RecA表达上调、大量DNA损伤及膜电位去极化。基于此，我们拟进一步研究RecA-LexA介导的细菌类凋亡程序性死亡（ALD）参与光动力作用灭活铜绿假单胞菌的作用机制；首先测定光动力作用对假单胞菌RecA表达，LexA裂解及下游Edin基因表达的影响，探究光动力作用对假单胞菌RecA-LexA途径的激活；并进一步检测光动力作用降低假单胞菌氧化呼吸链活力，诱导细胞膜去极化和磷脂酰丝氨酸外翻，引起细菌基因组DNA凝聚化和片段化，及rRNA降解等细菌程序性死亡事件；结合RecA缺失菌株的构建；从而明确RecA-LexA介导的细菌类凋亡程序性死亡在姜黄素光动力非热灭活假单胞菌中所发挥的作用机制。该研究为阐明光动力非热灭活食源有害菌的作用机制提供理论基础。

As a conditional pathogenic bacterium frequently isolated from frozen aquatic food products, pseudomonas aeruginosa may cause severe or even fatal infection to humans. Our previous studies have demonstrated that LED-activated curcumin-mediated non-thermal photodynamic action could efficiently sterilize Pseudomonas aeruginosa by inducing the increase of RecA expression, bacteria DNA damage and membrane depolarization, which suggested RecA-LexA mediated bacterial apoptosis-like programmed cell death (ALD) may be one of the underlying mechanisms by which the photodynamic action kills Pseudomonas aeruginosa. In order to further explore this mechanism, we proposed to further analyze the effects of photodynamic treatment on the expression of RecA, the degradation of LexA as well as the expression of downstream Edin genes to confirm the activation of RecA-LexA pathway. Furthermore, the characteristic apoptosis-like programmed cell death (ALD) events including the decrease in the oxidation respiratory chain activity, the membrane depolarization and phosphatidylserine exposure, the condensation and fragmentation of bacterial genome DNA and the degradation of rRNA will be evaluated in Pseudomonas aeruginosa after the photodynamic treatment to confirm the bacterial apoptosis-like programmed cell death (ALD) can be activated by curcumin-mediated photodynamic treatment. Finally, the role of RecA-LexA mediated bacterial apoptosis-like death (ALD) in curcumin-mediated photodynamic action against Pseudomonas aeruginosa will be further confirm by RecA-knockout Pseudomonas aeruginosa strain. This study may lead to a better understanding towards the mechanism of non-thermal antimicrobial photodynamic inactivation.