Bacterial exopolysaccharides (EPS) are high-molecular weight polysaccharides that are loosely attached to the cell surface or excreted in the environment (Figure 1) . Their molecular structures vary among different strains , and can contain unusual carbohydrates and glycosidic linkages that are not found in eukaryotes. EPS have been studied extensively in the past years as they are part of bacterial biofilms, and combine interesting technological properties with promising effects on human health . For example L. plantarum EPS might have a potential as antitumor drug , one of the EPS fractions isolated from B. animalis is under investigation for the effects on mucosal immunity in the small intestine  and the EPS released by L. rhamnosus might be useful in the treatment of metabolic disorders .
To gain more insight into the EPS structures that confer health effects, these molecules have to be isolated from the producing bacteria. An ideal isolation method should be applicable to different strains and lead to the isolation of the polysaccharides without any interference from medium components or contamination with cell’s content.
In the current study we present the advancements in the isolation of EPS from several (an)aerobic strains, focusing mainly on Lactobacillus and Bifidobacterium spp, and compare the results obtained using different media and extraction procedures. The final goal is the development of a general isolation and purification method suitable to perform the study of these potential healthy natural products.
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