Iraporda Carolina, Abatemarco Júnior Mário, Neumann Elisabeth, Nunes Álvaro Cantini, Nicoli Jacques R, Abraham Analía G, Garrote Graciela L
Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA, UNLP-CONICET),Calle 47 y 116. La Plata (1900),Bs. As.,Argentina.
Department of Microbiology,Institute of Biological Sciences,Federal University of Minas Gerais (UFMG),Av. Antonio Carlos 6627,31270-901. Belo Horizonte,Brazil.
J Dairy Res. 2017 Aug;84(3):339-345. doi: 10.1017/S0022029917000358.
Kefir is a fermented milk obtained by the activity of kefir grains which are composed of lactic and acetic acid bacteria, and yeasts. Many beneficial health effects have been associated with kefir consumption such as stimulation of the immune system and inhibition of pathogenic microorganisms. The biological activity of kefir may be attributed to the presence of a complex microbiota as well as the microbial metabolites that are released during fermentation. The aim of this work was to characterise the non-microbial fraction of kefir and to study its antagonism against Escherichia coli, Salmonella spp. and Bacillus cereus. During milk fermentation there was a production of organic acids, mainly lactic and acetic acid, with a consequent decrease in pH and lactose content. The non-microbial fraction of kefir added to nutrient broth at concentrations above 75% v/v induced a complete inhibition of pathogenic growth that could be ascribed to the presence of un-dissociated lactic acid. In vitro assays using an intestinal epithelial cell model indicated that pre-incubation of cells with the non-microbial fraction of kefir did not modify the association/invasion of Salmonella whereas pre-incubation of Salmonella with this fraction under conditions that did not affect their viability significantly decreased the pathogen's ability to invade epithelial cells. Lactate exerted a protective effect against Salmonella in a mouse model, demonstrating the relevance of metabolites present in the non-microbial fraction of kefir produced during milk fermentation.
开菲尔是一种通过开菲尔粒的活性获得的发酵乳，开菲尔粒由乳酸菌、醋酸菌和酵母组成。食用开菲尔与许多有益健康的作用相关，如刺激免疫系统和抑制病原微生物。开菲尔的生物活性可能归因于复杂的微生物群的存在以及发酵过程中释放的微生物代谢产物。这项工作的目的是表征开菲尔的非微生物部分，并研究其对大肠杆菌、沙门氏菌属和蜡样芽孢杆菌的拮抗作用。在牛奶发酵过程中产生了有机酸，主要是乳酸和醋酸，导致pH值和乳糖含量降低。以高于75% v/v的浓度添加到营养肉汤中的开菲尔非微生物部分可完全抑制病原菌生长，这可能归因于未解离乳酸的存在。使用肠道上皮细胞模型的体外试验表明，用开菲尔非微生物部分预孵育细胞不会改变沙门氏菌的黏附/侵袭，而在不显著影响其活力的条件下用该部分预孵育沙门氏菌会显著降低病原菌侵袭上皮细胞的能力。乳酸在小鼠模型中对沙门氏菌发挥了保护作用，证明了牛奶发酵过程中开菲尔非微生物部分中存在的代谢产物的相关性。
