Siroli Lorenzo, Braschi Giacomo, Rossi Samantha, Gottardi Davide, Patrignani Francesca, Lanciotti Rosalba
Department of Agricultural and Food Sciences, University of Bologna, p.zza Goidanich 60, 47521 Cesena, Italy.
Interdepartmental Center for Industrial Agri-food Research, University of Bologna, Piazza Goidanich 60, 47521 Cesena, Italy.
Microorganisms. 2020 Mar 20;8(3):439. doi: 10.3390/microorganisms8030439.
Sub-lethal high-pressure homogenization treatments applied to A13 demonstrated to be a useful strategy to enhance technological and functional properties without detrimental effects on the viability of this strain. Modification of membrane fatty acid composition is reported to be the main regulatory mechanisms adopted by probiotic lactobacilli to counteract high-pressure stress. This work is aimed to clarify and understand the relationship between the modification of membrane fatty acid composition and the expression of genes involved in fatty acid biosynthesis in A13, before and after the application of different sub-lethal hyperbaric treatments. Our results showed that A13 activated a series of reactions aimed to control and stabilize membrane fluidity in response to high-pressure homogenization treatments. In fact, the production of cyclic fatty acids was counterbalanced by the unsaturation and elongation of fatty acids. The gene expression data indicate an up-regulation of the genes , , , and after high-pressure homogenization treatment at 150 and 200 MPa, and of and after a treatment at 200 MPa suggesting this regulation of the genes involved in fatty acids biosynthesis as an immediate response mechanism adopted by A13 to high-pressure homogenization treatments to balance the membrane fluidity. Although further studies should be performed to clarify the modulation of phospholipids and glycoproteins biosynthesis since they play a crucial role in the functional properties of the probiotic strains, this study represents an important step towards understanding the response mechanisms of A13 to sub-lethal high-pressure homogenization treatments.
对A13进行的亚致死高压均质处理被证明是一种有用的策略，可增强其技术和功能特性，而不会对该菌株的活力产生不利影响。据报道，膜脂肪酸组成的改变是益生菌乳酸杆菌对抗高压胁迫所采用的主要调节机制。这项工作旨在阐明和理解在应用不同的亚致死高压处理前后，A13中膜脂肪酸组成的改变与参与脂肪酸生物合成的基因表达之间的关系。我们的结果表明，A13激活了一系列旨在响应高压均质处理来控制和稳定膜流动性的反应。事实上，环状脂肪酸的产生被脂肪酸的不饱和度和延长所抵消。基因表达数据表明，在150和200MPa的高压均质处理后，基因、、、和上调，在200MPa处理后和上调，这表明参与脂肪酸生物合成的基因的这种调节是A13对高压均质处理采取的一种即时反应机制，以平衡膜流动性。尽管还需要进一步研究来阐明磷脂和糖蛋白生物合成的调节，因为它们在益生菌菌株的功能特性中起着关键作用，但这项研究是朝着理解A13对亚致死高压均质处理的反应机制迈出的重要一步。
