Effect of high pressure (HP) treatment on the antimicrobial properties and the structure of nisin was evaluated. Nisin solutions at pH 2.8 or 6.1 were treated by HP at 500 MPa – 10 min – 20 °C and their antimicrobial potency was determined. It appeared that HP clearly impacted the antimicrobial activity of nisin, with respective activity loss of 22.5% and 49.9% at pH 2.8 and 6.1. Structural analysis of nisin by circular dichroism and Fourier transform-infrared spectroscopies revealed that the decrease of nisin antimicrobial activity was likely due to the unfolding of the protein induced by HP. A loss of nisin β-turns structure, particularly significant at neutral pH, was linked to the drastic drop in antimicrobial activity, as these structures are implicated in the nisin interaction with the bacterial membrane.

Industrial relevance

The combination of nisin and high pressure (HP) can be use at an industrial scale to inactivate bacteria. Nisin is allowed as a food additive (E234) and can be added at a final concentration ranging from 120 to 500 IU/g, depending on the product. In this work, we showed that HP can induce a significant reduction of nisin activity (-22.5% at pH 2.8 and -49.9% at pH 6.1). Therefore, this activity loss could be taken into account to manage the final nisin concentration in HP-treated food products.

中文翻译：

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高压对细菌素乳链菌肽的抗菌活性和二级结构的影响

评估了高压（HP）处理对乳酸链球菌素的抗菌性能和结构的影响。用HP在500 MPa – 10分钟– 20°C下处理pH 2.8或6.1的乳链菌肽溶液，并确定其抗菌效力。似乎HP明显影响了乳链菌肽的抗菌活性，在pH 2.8和6.1时活性分别降低了22.5％和49.9％。通过圆二色性和傅立叶变换红外光谱对乳链菌肽进行结构分析，结果表明，乳链菌肽的抗菌活性降低可能是由于HP诱导的蛋白质解折叠。乳链菌肽β-转角结构的丧失，特别是在中性pH时尤为明显，这与抗菌活性的急剧下降有关，因为这些结构与乳链菌肽与细菌膜的相互作用有关。

行业相关性

乳链菌肽和高压（HP）的组合可用于工业规模以灭活细菌。允许使用乳链菌肽作为食品添加剂（E234），并且可以根据产品的最终浓度在120至500 IU / g的范围内添加。在这项工作中，我们表明HP可以诱导乳链菌肽活性显着降低（在pH 2.8时为-22.5％，在pH 6.1时为-49.9％）。因此，可以将这种活动损失考虑在内，以管理经过HP处理的食品中的最终乳链菌肽浓度。