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Eighteen lactic acid bacteria (LAB) strains isolated from dairy products, all identified as Lactobacillus delbrueckii subsp. bulgaricus, were tested for their ability to grow on three different oligosaccharides: fructo-oligosaccharides (FOS), gluco-oligosaccharides (GOS) and galacto-oligosaccharides (GalOS). The growth of LAB on different oligosaccharides was very different. Study of the antimicrobial activities of these LAB indicated that the system of uptake of unusual sugars influenced in a specific way the production of antimicrobial substances (bacteriocins) specific against gram-negative bacteria. The added oligosaccharides induced LAB to form end-products of a typical mixed acid fermentation. The utilization of different types of oligosaccharides may help to explain the ability of Lactobacillus strains to compete with other bacteria in the ecosystem of the human gastro-intestinal tract.

Breastfeeding is essential in the first months of a newborn's life. Breast milk is a source of crucial macronutrients, prebiotic oligosaccharides, and potential probiotic strains of bacteria. Oligosaccharides from breast milk (HMOs) are a significant part of the composition of breast milk and represent a complex of digestible sugars. This study aims to elucidate the enzymatic hydrolysis of these oligosaccharides and other prebiotics by the bacteria present in breast milk. We used modified methods to isolate oligosaccharides (HMOs) from human milk. Using unique techniques, we isolated and identified different bacteria from breast milk, mainly Lactobacillus fermentum. Using enzymatic analyses, we established the participation of α-fucosidase, α-glucosidase, β-galactosidase, and β-glucosidase from breast milk bacteria in the hydrolysis of prebiotic sugars. We also optimized the scheme for isolating oligosaccharides from breast milk by putting the lyophilized product into different food media. We found that the oligosaccharides from breast milk (HMOs) are a potent inducer for the secretion of the studied bacterial enzymes. Also, we found that all the lactobacilli strains we studied in detail could digest mucin-linked glycans. The degradation of these sugars is perhaps a built-in defense mechanism in cases where other sugars are lacking in the environment. We also determined fucosidase activity in some of the isolated strains. We recorded the highest values (2.5 U/mg in L. fermentum ss8) when the medium's oligosaccharides isolated from breast milk were present. Lactobacilli and Bifidobacteria supplied with breast milk are the first colonizers in most cases in the gastrointestinal tract of the newborn. The presence and study of different genes for synthesizing other enzyme systems and transporters of various sugars in this type of bacteria are essential. [ABSTRACT FROM AUTHOR]

This study examined the effect of lactulose, galactooligosaccharide, fructooligosaccharide, inulin, and β-glucan on the probiotic strain Lactobacillus delbrueckii subsp. bulgaricus L14, cultivated in an in vitro gastrointestinal system model. We analyzed the degree of hydrolysis of the studied prebiotic oligosaccharides in condition of simulated gastric fluid. The results showed that lactulose had the highest resistance, galactooligosaccharide underwent hydrolysis, and fructooligosaccharide was the most sensitive. Among the polysaccharides, fructose was released from inulin and glucose from β-glucan. Short-chain oligosaccharides and metabolites derived from studied prebiotic oligosaccharides and polysaccharides, supported the growth of probiotic strain L14, which showed the highest growth with fructooligosaccharides and β-glucan as carbohydrate sources. The profile of the activated enzymes secreted by the probiotic strain L14, indicated their inducible character. Beta-galactosidase was activated in the presence of lactulose and GalOS, inulinase was activated in the presence of inulin and fructooligosaccharides, and β-glucosidase was activated in the presence of β-glucan fragments. Analysis of the produced organic and short-chain fatty acids showed that the typical representative of the homofermentative lactobacilli Lb. delbrueckii subsp. bulgaricus L14 changes its metabolism from a homofermentative to a heterofermentative type, best expressed in the presence of lactulose, galactooligosaccharide, and β-glucan. [ABSTRACT FROM AUTHOR]

In this work, we reported production of glucansucrases with molecular weights of about 300 kDa by strains of fructophilic lactic acid bacteria (FLAB) Lactobacillus pentosus AG8, Lactobacillus kunkeei AG9, AG10 and AG11 isolated from the gut of honey bee Apis mellifera. From sucrose, these enzymes synthesize average to high-molecular-weight dextran-type glucans ranging from 8.5 × 105 to >4 × 106 Da and containing 16 to 22% α-(1→3)-linked glucose units, with 5 to 8% branching in their structures. Enzyme preparations from the strains were applied in the synthesis of glucooligosaccharides (GOSs) with degrees of polymerization (DP) from 3 to 7 using maltose/sucrose ratios (M/S) from 8 to 0.12. The yields and composition of the obtained oligosaccharide products were strongly influenced by the ratios of the acceptor and donor of glucose units in the reactions. The highest yields of GOSs (>50 g/L) were achieved at M/S = 1, and the lowest content of α-(1→6) linkages (71%) combined with increased proportion of the products with DP > 3 were determined at M/S = 0.5. GOSs preparations from these two ratios were able to maintain the growth and acids production of three probiotic strains of lactobacilli, suggesting potential application as prebiotics. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the prebiotic potential of Plantago major L. leaves water-extractable polysaccharide (PWPs) and its lower molecular fractions. The structure of PWPs was investigated by high pressure anion exchange chromatography (HPAEC), size exclusion chromatography coupled with multi-angle laser light scattering detector (SEC-MALLS) and Fourier-transform infrared (FTIR) spectroscopy. The chemical composition and monosaccharide analyses showed that galacturonic acid was the main monosaccharide of PWPs followed by glucose, arabinose, galactose, rhamnose and xylose. FTIR study indicated a strong characteristic absorption peak at 1550 cm−1 corresponding to the vibration of COO− group of galacturonic acid. The PWPs was subjected to hydrolysis using commercial enzymes to obtain P. major low molecular fraction (PLM) which was successively separated by size exclusion chromatography on Biogel P2. PWPs and PLM were examined for in vitro prebiotic activity using various assays. Results gave evidence for changes in optical density of the bacteria cells and pH of the growth medium. A heterofermentative process with a lactate/acetate ratio ranged from 1:1 to 1:5 was observed. The ability of PLM to stimulate the production of certain probiotic bacteria glycohydrolases and to be fermented by Lactobacillus sp. strains was successfully proved. [ABSTRACT FROM AUTHOR]

Beta-galactosidase (EC.3.2.1.23) is an important enzyme industrially used for the hydrolysis of lactose from milk and milk whey for several applications. Lately, the importance of this enzyme was enhanced by its galactosyltransferase activity, which is responsible for synthesis of transgalactosylated oligosaccharides that act as prebiotics with several beneficial effects on the consumers. ß-Galactosidase production by Kluyveromyces lactis 3 was studied in shake flask culture. The highest enzymatic activity was obtained at 10-th hour of the fermentation. The optimum temperature for transferase activity was 50°C. When incubated with 30% lactose in 50 mM phosphate buffer (pH 6.0) the enzyme can synthesize up to 41% galacto-oligosaccharides (GalOS). ß-Galactosidase from strain Kluyveromyces lactis 3 produces mainly oligosaccharides with degree of polymerization (DP) 6 at 40°C and with DP 3 at 50°C. [ABSTRACT FROM AUTHOR]

Three lactic acid bacteria (LAB) strains identified as Lactobacillus plantarum, Lactobacillus brevis, and Lactobacillus sakei isolated from meat products were tested for their ability to utilize and grow on xylooligosaccharides (XOSs). The extent of carbohydrate utilization by the studied strains was analyzed by HPLC. All three strains showed preferences for the degree of polymerization (DP). The added oligosaccharides induced the LAB to form end-products of typical mixed-acid fermentation. The utilization of XOSs by the microorganisms requires the action of three important enzymes: β-xylosidase (EC 3.2.1.37) exo-oligoxylanase (EC 3.2.1.156) and α-L-arabinofuranosidase (EC 3.2.1.55). The presence of intracellular β-D-xylosidase in Lb. brevis, Lb. plantarum, and Lb. sakei suggest that XOSs might be the first imported into the cell by oligosaccharide transporters, followed by their degradation to xylose. The studies on the influence of XOS intake on the lipids of rat liver plasma membranes showed that oligosaccharides display various beneficial effects for the host organism, which are probably specific for each type of prebiotic used. The utilization of different types of oligosaccharides may help to explain the ability of Lactobacillus strains to compete with other bacteria in the ecosystem of the human gastrointestinal tract. [ABSTRACT FROM AUTHOR]