Yogurt is a traditional fermented dairy product, prepared with starter cultures containing Streptococcus thermophilus and Lactobacillus bulgaricus that has gained widespread consumer acceptance as a healthy food. It is widely accepted that yogurt cultures have been recognized as probiotics, due to their beneficial effects on human health. In this study, we have characterized technological and health-promoting properties of autochthonous strains S. thermophilus BGKMJ1-36 and L. bulgaricus BGVLJ1-21 isolated from artisanal sour milk and yogurt, respectively, in order to be used as functional yogurt starter cultures. Both BGKMJ1-36 and BGVLJ1-21 strains have the ability to form curd after five hours at 42 °C, hydrolyze α_s1-, β-, and κ- casein, and to show antimicrobial activity toward Listeria monocytogenes. The strain BGKMJ1-36 produces exopolysaccharides important for rheological properties of the yogurt. The colonies of BGKMJ1-36 and BGVLJ1-21 strains that successfully survived transit of the yogurt through simulated gastrointestinal tract conditions have been tested for adhesion to intestinal epithelial Caco-2 cells. The results reveal that both strains adhere to Caco-2 cells and significantly upregulate the expression of autophagy-, tight junction proteins-, and anti-microbial peptides-related genes. Hence, both strains may be interesting for use as a novel functional starter culture for production of added-value yogurt with health-promoting properties.

中文翻译：

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由新型天然发酵剂生产的酸奶可改善体外肠道上皮屏障


酸奶是一种传统的发酵乳制品，由含有嗜热链球菌和保加利亚乳杆菌的发酵剂制成，作为健康食品已获得消费者的广泛认可。人们普遍认为酸奶培养物被认为是益生菌，因为它们对人类健康有益。在这项研究中，我们表征了分别从手工酸牛奶和酸奶中分离的本地菌株嗜热链球菌BGKMJ1-36 和保加利亚乳杆菌BGVLJ1-21 的技术和促进健康的特性，以便将其用作功能性酸奶发酵剂培养物。 BGKMJ1-36 和 BGVLJ1-21 菌株均能够在 42°C 下 5 小时后形成凝乳，水解 α _s1- 、 β-和κ-酪蛋白，并对单核细胞增生李斯特菌表现出抗菌活性。菌株 BGKMJ1-36 产生的胞外多糖对于酸奶的流变特性非常重要。 BGKMJ1-36 和 BGVLJ1-21 菌株在模拟胃肠道条件下的酸奶转运中成功存活，并已测试其与肠上皮 Caco-2 细胞的粘附性。结果表明，两种菌株均粘附在 Caco-2 细胞上，并显着上调自噬、紧密连接蛋白和抗菌肽相关基因的表达。因此，这两种菌株可能有兴趣用作新型功能性发酵剂，用于生产具有促进健康特性的增值酸奶。