目的:欧姆加热(即通过电场加热)比传统的湿法加热更有效地杀死细菌孢子,然而,其机制仍然知之甚少。本研究探讨了使用转基因孢子加速孢子失活机制。
结果:我们研究了欧姆(OH)和常规加热(CH)对各种转基因枯草芽孢杆菌菌株的影响:同基因PS533(野生型_1),PS578(缺乏孢子\'α/β型小酸溶性蛋白(SASP)),PS2318(缺乏recA,编码DNA修复蛋白),和等基因PS4461(野生型_2),和PS4462(在孢子中具有2Duf蛋白,这增加了孢子的耐湿热性并降低了孢子内膜的流动性)。SASP的去除使OH和CH的失活谱更接近,表明这些蛋白质与磁场的相互作用。然而,在最高的测试场强下,缺乏SASP的孢子的CH和OH杀死之间的差异再次出现,表明该场与另一个孢子核心成分也存在相互作用。此外,RecA缺陷孢子产生的结果与野生型CH孢子相似,而该突变体的OH抗性在较低的测试温度下增加,这意味着RecA或DNA可能是电场的额外靶标。添加2Duf蛋白显着增加了对CH和OH的孢子抗性,尽管在50V/cm的OH下观察到杀死的速度有所加快。
结论:总之,膜流动性和孢子核心蛋白与电场的相互作用是电场-热组合增强孢子杀伤的关键因素。
OBJECTIVE: Ohmic heating (OH) (i.e. heating by electric field) more effectively kills bacterial spores than traditional wet heating, yet its mechanism remains poorly understood. This study investigates the accelerated
spore inactivation mechanism using genetically modified spores.
RESULTS: We investigated the effects of OH and conventional heating (CH) on various genetically modified strains of Bacillus subtilis: isogenic PS533 (wild type_1), PS578 [lacking spores\' α/β-type small acid-soluble proteins (SASP)], PS2318 (lacking recA, encoding a DNA repair protein), isogenic PS4461 (wild type_2), and PS4462 (having the 2Duf protein in spores, which increases spore wet heat resistance and decreases
spore inner membrane fluidity). Removal of SASP brought the inactivation profiles of OH and CH closer, suggesting the interaction of these proteins with the field. However, the reemergence of a difference between CH and OH killing for SASP-deficient spores at the highest tested field strength suggested there is also interaction of the field with another
spore core component. Additionally, RecA-deficient spores yielded results like those with the wild-type spores for CH, while the OH resistance of this mutant increased at the lower tested temperatures, implying that RecA or DNA are a possible additional target for the electric field. Addition of the 2Duf protein markedly increased spore resistance both to CH and OH, although some acceleration of killing was observed with OH at 50 V/cm.
CONCLUSIONS: In summary, both membrane fluidity and interaction of the
spore core proteins with electric field are key factors in enhanced
spore killing with electric field-heat combinations.