Borch-Pedersen Kristina, Mellegård Hilde, Reineke Kai, Boysen Preben, Sevenich Robert, Lindbäck Toril, Aspholm Marina
Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, the Norwegian University of Life Sciences, Oslo, Norway.
Quality and Safety of Food and Feed, Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB), Potsdam, Germany.
Appl Environ Microbiol. 2017 Jun 30;83(14). doi: 10.1128/AEM.00503-17. Print 2017 Jul 15.
and species form spores, which pose a challenge to the food industry due to their ubiquitous nature and extreme resistance. Pressurization at <300 MPa triggers spore germination by activating germination receptors (GRs), while pressurization at >300 MPa likely triggers germination by opening dipicolinic acid (DPA) channels present in the inner membrane of the spores. In this work, we expose spores of , a species associated with food spoilage and occasionally with food poisoning, to high pressure (HP) for holding times of up to 2 h. By using mutant spores lacking one or several GRs, we dissect the roles of the GerA, Ynd, and GerK GRs in moderately HP (mHP; 150 MPa)-induced spore germination. We show that Ynd alone is sufficient for efficient mHP-induced spore germination. GerK also triggers germination with mHP, although at a reduced germination rate compared to that of Ynd. GerA stimulates mHP-induced germination but only in the presence of either the intact GerK or Ynd GR. These results suggests that the effectiveness of the individual GRs in mHP-induced germination differs from their effectiveness in nutrient-induced germination, where GerA plays an essential role. In contrast to spores, treatment with very HP (vHP) of 550 MPa at 37°C did not promote effective germination of spores. However, treatment with vHP in combination with elevated temperatures (60°C) gave a synergistic effect on spore germination and inactivation. Together, these results provide novel insights into how HP affects spore germination and inactivation and the role of individual GRs in this process. Bacterial spores are inherently resistant to food-processing regimes, such as high-temperature short-time pasteurization, and may therefore compromise food durability and safety. The induction of spore germination facilitates subsequent inactivation by gentler processing conditions that maintain the sensory and nutritional qualities of the food. High-pressure (HP) processing is a nonthermal food-processing technology used to eliminate microbes from food. The application of this technology for spore eradication in the food industry requires a better understanding of how HP affects the spores of different bacterial species. The present study provides novel insights into how HP affects spores, a species associated with food spoilage and occasionally food poisoning. We describe the roles of different germination receptors in HP-induced germination and the effects of two different pressure levels on the germination and inactivation of spores. This study will potentially contribute to the effort to implement HP technology for spore inactivation in the food industry.
并且该菌种会形成孢子,由于其广泛存在的特性和极强的抗性,给食品工业带来了挑战。低于300兆帕的压力通过激活萌发受体(GRs)触发孢子萌发,而高于300兆帕的压力可能通过打开孢子内膜中存在的吡啶二羧酸(DPA)通道来触发萌发。在这项工作中,我们将与食品腐败以及偶尔与食物中毒相关的该菌种的孢子暴露于高压(HP)下长达2小时。通过使用缺乏一种或几种GRs的突变孢子,我们剖析了GerA、Ynd和GerK GRs在中等高压(mHP;150兆帕)诱导的孢子萌发中的作用。我们表明,单独的Ynd就足以实现高效的mHP诱导的孢子萌发。GerK也能在mHP下触发萌发,尽管与Ynd相比萌发率有所降低。GerA能刺激mHP诱导的萌发,但仅在完整的GerK或Ynd GR存在的情况下。这些结果表明,单个GRs在mHP诱导的萌发中的有效性与其在营养物诱导的萌发中的有效性不同,在营养物诱导的萌发中GerA起着至关重要的作用。与该菌种的孢子不同,在37°C下用550兆帕的极高压力(vHP)处理并不能促进该菌种孢子的有效萌发。然而,vHP与升高的温度(60°C)联合处理对孢子萌发和失活产生了协同作用。总之,这些结果为高压如何影响该菌种孢子的萌发和失活以及单个GRs在此过程中的作用提供了新的见解。细菌孢子对诸如高温短时巴氏杀菌等食品加工方式具有内在抗性,因此可能会损害食品的耐久性和安全性。诱导孢子萌发有助于通过更温和的加工条件进行后续失活,同时保持食品的感官和营养品质。高压(HP)加工是一种用于从食品中消除微生物的非热食品加工技术。在食品工业中应用该技术消除孢子需要更好地了解高压如何影响不同细菌菌种的孢子。本研究为高压如何影响与食品腐败以及偶尔食物中毒相关的该菌种的孢子提供了新的见解。我们描述了不同萌发受体在高压诱导萌发中的作用以及两种不同压力水平对孢子萌发和失活的影响。这项研究可能有助于在食品工业中实施高压技术以实现孢子失活的努力。