Production of exopolysaccharides by Lactobacillus and Bifidobacterium strains of human origin, and metabolic activity of the producing bacteria in milk
Production of exopolysaccharides by Lactobacillus and Bifidobacterium strains of human origin, and metabolic activity of the producing bacteria in milk
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DOI：
10.3168/jds.2009-2126
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发表时间：
2009-09-01
影响因子：
3.5
通讯作者：
Ruas-Madiedo, P.
中科院分区：
文献类型：
--
作者：
Salazar, N.;Prieto, A.;Ruas-Madiedo, P.
本文报道了从人类肠道微生物群中分离的乳杆菌和双歧杆菌菌株产生的21种外多糖（EPS）的理化特性，以及产EPS菌株在牛奶中的生长和代谢活性。这些菌株属于干酪乳杆菌、鼠李糖乳杆菌、植物乳杆菌、阴道乳杆菌、动物双歧杆菌、长双歧杆菌和假钩状双歧杆菌。EPS组分的摩尔质量分布呈2个不同大小的峰，这与部分食品源性细菌EPS具有相同的特征。总的来说，我们发现了EPS大小分布与产生EPS的物种之间的关联，尽管由于测试的人类细菌EPS数量较少，我们无法最终建立相关性。所研究的EPS的主要单糖成分是葡萄糖、半乳糖和鼠李糖，与食品聚合物中的单糖成分相同；然而，鼠李糖和葡萄糖的比例通常高于我们人类细菌EPS中的半乳糖比例。所有产eps菌株均能生长并使牛奶酸化；大多数乳酸菌产生乳酸作为主要代谢物。双歧杆菌乳酸与乙酸的比值为0.7，接近理论比值，说明产生eps的菌株不会产生过量的乙酸，而乙酸会对发酵乳的感官特性产生不利影响。在增粘能力方面，L. plantarum H2和L. rhamnosus E41和E43R能够增加搅拌发酵乳的粘度，其程度与产生eps的嗜热链球菌菌株作为阳性对照相似。因此，如果能够证明益生菌的特性，这些产生eps的人类细菌可以作为混合培养剂用于功能食品的配方。本文首次报道了从人肠道微生物群中分离得到的EPS的理化特性。
This work reports on the physicochemical characterization of 21 exopolysaccharides (EPS) produced by Lactobacillus and Bifidobacterium strains isolated from human intestinal microbiota, as well as the growth and metabolic activity of the EPS-producing strains in milk. The strains belong to the species Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus plantarum, Lactobacillus vaginalis, Bifidobacterium animalis, Bifidobacterium longum, and Bifidobacterium pseudocatenulatum. The molar mass distribution of EPS fractions showed 2 peaks of different sizes, which is a feature shared with some EPS from bacteria of food origin. In general, we detected an association between the EPS size distribution and the EPS-producing species, although because of the low numbers of human bacterial EPS tested, we could not conclusively establish a correlation. The main monosaccharide components of the EPS under study were glucose, galactose, and rhamnose, which are the same as those found in food polymers; however, the rhamnose and glucose ratios was generally higher than the galactose ratio in our human bacterial EPS. All EPS-producing strains were able to grow and acidify milk; most lactobacilli produced lactic acid as the main metabolite. The lactic acid-to-acetic acid ratio in bifidobacteria was 0.7, close to the theoretical ratio, indicating that the EPS-producing strains did not produce an excessive amount of acetic acid, which could adversely affect the sensory properties of fermented milks. With respect to their viscosity-intensifying ability, L. plantarum H2 and L. rhamnosus E41 and E43R were able to increase the viscosity of stirred, fermented milks to a similar extent as the EPS-producing Streptococcus thermophilus strain used as a positive control. Therefore, these human EPS-producing bacteria could be used as adjuncts in mixed cultures for the formulation of functional foods if probiotic characteristics could be demonstrated. This is the first article reporting the physicochemical characteristics of EPS isolated from human intestinal microbiota.