Food Hygiene and Safety, Institute of Meat Products, University of Extremadura, Cáceres, Spain.
Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland.
Food Microbiol. 2017 Sep;66:1-10. doi: 10.1016/j.fm.2017.03.015. Epub 2017 Mar 22.
The ability of Aspergillus flavus to produce aflatoxins in dairy products presents a potential hazard. The antifungal protein PgAFP from Penicillium chrysogenum inhibits various foodborne toxigenic fungi, including Aspergillus flavus. However, PgAFP did not inhibit A. flavus growth in cheese, which was related to the associated cation content. CaCl increased A. flavus permeability and prevented PgAFP-mediated inhibition in potato dextrose broth (PDB). PgAFP did not elicit any additional increase in permeability of CaCl-incubated A. flavus. Furthermore, PgAFP did not alter metabolic capability, chitin deposition, or hyphal viability of A. flavus grown with CaCl. Comparative proteomic analysis after PgAFP treatment of A. flavus in calcium-enriched PDB revealed increased abundance of 125 proteins, including oxidative stress-related proteins, as determined by label-free mass spectrometry (MS)-based proteomics. Seventy proteins were found at lower abundance, with most involved in metabolic pathways and biosynthesis of secondary metabolites. These changes do not support the blockage of potential PgAFP receptors in A. flavus by calcium as the main cause of the protective role. A. flavus resistance appears to be mediated by calcineurin, G-protein, and γ-glutamyltranspeptidase that combat oxidative stress and impede apoptosis. These findings could serve to design strategies to improve PgAFP activity against aflatoxigenic moulds in dairy products.
黄曲霉在乳制品中产生黄曲霉毒素的能力存在潜在危害。来自产黄青霉的真菌抗菌蛋白 PgAFP 抑制了包括黄曲霉在内的多种食源性病原体真菌。然而，PgAFP 并没有抑制奶酪中的黄曲霉生长，这与相关阳离子含量有关。氯化钙增加了黄曲霉的通透性，并阻止了 PgAFP 在马铃薯葡萄糖肉汤（PDB）中的介导抑制作用。PgAFP 不会引起氯化钙孵育的黄曲霉通透性的任何其他增加。此外，PgAFP 不会改变用 CaCl 培养的黄曲霉的代谢能力、几丁质沉积或菌丝活力。用 PgAFP 处理富含钙的 PDB 中的黄曲霉后，通过无标记质谱（MS）-基于蛋白质组学的比较蛋白质组分析显示，125 种蛋白质的丰度增加，包括与氧化应激相关的蛋白质。发现 70 种蛋白质的丰度较低，其中大多数涉及代谢途径和次生代谢物的生物合成。这些变化不支持钙作为 PgAFP 受体阻断的主要原因，从而保护黄曲霉免受影响。黄曲霉的抗性似乎是由钙调神经磷酸酶、G 蛋白和γ-谷氨酰转肽酶介导的，这些酶可以对抗氧化应激并阻止细胞凋亡。这些发现可以为设计策略提供依据，以提高 PgAFP 对乳制品中产黄曲霉的活性。
