Spores of wild-type Bacillus subtilis PS533 were treated by wet heat at 75 °C for 30 min, and high pressure CO₂ (HPCD) at 6.5 MPa and 30 °C or 75 °C for 30 min. The spores were analyzed for wet heat resistance (85 °C, 90 °C, 95 °C) and typical germination events including DPA release and cortex hydrolysis, inner membrane permeability, and germination triggered by nutrient (L-valine and AGFK) or non-nutrient (dodecylamine and high pressure at 150 MPa or 550 MPa) germinants. The results showed that (i) HPCD-treated spores exhibited reduced wet heat resistance compared to the untreated or wet heat-treated spores; (ii) HPCD-treated spores did not undergo typical germination events such as DPA release or cortex hydrolysis compared to normally germinated spores; (iii) HPCD-treated spores released more metal ions and exhibited decreased ability to maintain DPA, indicating that the permeability of inner membrane of HPCD-treated spores was increased; (iv) HPCD-treated spores exhibited reduced germination rate when triggered by L-valine or 150 MPa, but increased germination rate when triggered by dodecylamine or 550 MPa, suggesting that the fluidity of the inner membrane of HPCD-treated spores might be increased. These results indicated that HPCD could reduce the wet heat resistance of spores, and this resistance decrease was probably due to the modification of the inner membrane caused by HPCD.

Industrial relevance

The extremely high wet heat resistance of spores makes them a significant problem in the thermal processing of foods. Thus, it of great interest to develop a process to reduce the wet heat resistance of spores. In this work, we found that HPCD can significantly reduce the wet heat resistance of B. subtilis spores, and this was achieved by perturbing the inner membrane of spores. These results can improve our understanding of the inactivation mechanism of spores by HPCD, and also provide an alternative approach for spore inactivation in foods.

中文翻译：

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高压CO ₂通过扰动内膜降低了枯草芽孢杆菌孢子的湿热阻

将野生型枯草芽孢杆菌PS533的孢子在75°C下湿热处理30分钟，并用高压CO _2处理。（HPCD）在6.5 MPa和30°C或75°C下处理30分钟。分析孢子的湿耐热性（85°C，90°C，95°C）和典型的发芽事件，包括DPA释放和皮质水解，内膜通透性以及由养分（L-缬氨酸和AGFK）或非营养引起的发芽营养素（十二烷基胺和150 MPa或550 MPa的高压）。结果表明：（i）与未经处理或经湿热处理的孢子相比，经HPCD处理的孢子表现出降低的耐湿热性；（ii）与正常发芽的孢子相比，经HPCD处理的孢子没有发生典型的发芽事件，例如DPA释放或皮质水解；（iii）用HPCD处理过的孢子释放出更多的金属离子，并降低了维持DPA的能力，这表明用HPCD处理过的孢子的内膜通透性增加了；（iv）经HPCD处理的孢子在L-缬氨酸或150 MPa触发时发芽率降低，但在十二烷基胺或550 MPa触发时发芽率提高，表明HPCD处理的孢子内膜的流动性可能增加。这些结果表明，HPCD可以降低孢子的湿热阻，这种电阻降低可能是由于HPCD引起的内膜改性。

行业相关性

孢子的极高的湿耐热性使其成为食品热处理中的重要问题。因此，开发一种降低孢子的湿耐热性的方法引起了极大的兴趣。在这项工作中，我们发现HPCD可以显着降低枯草芽孢杆菌孢子的湿耐热性，这是通过扰动孢子的内膜来实现的。这些结果可以增进我们对HPCD灭活孢子机制的了解，也可以为食品中的灭活孢子提供另一种方法。