Exopolysaccharides produced by Lactobacillus and Bifidobacterium strains abrogate in vitro the cytotoxic effect of bacterial toxins on eukaryotic cells

Aims: To evaluate the capability of the exopolysaccharides (EPS) produced by lactobacilli and bifidobacteria from human and dairy origin to antagonize the cytotoxic effect of bacterial toxins. Methods and Results: The cytotoxicity of Bacillus cereus extracellular factors on Caco-2 colonocytes in the presence/absence of the EPS was determined by measuring the integrity of the tissue monolayer and the damage to the cell membrane (extracellular lactate dehydrogenase activity). Additionally, the protective effect of EPS against the haemolytic activity of the streptolysin-O was evaluated on rabbit erythrocytes. The EPS produced by Bifidobacterium animalis ssp. lactis A1 and IPLA-R1, Bifidobacterium longum NB667 and Lactobacillus rhamnosus GG were able to counteract the toxic effect of bacterial toxins on the eukaryotic cells at 1 mg ml-1 EPS concentration. The EPS A1 was the most effective in counteracting the effect of B. cereus toxins on colonocytes, even at lower doses (0.5 mg ml-1), whereas EPS NB667 elicited the highest haemolysis reduction on erythrocytes. Conclusions: The production of EPS by lactobacilli and bifidobacteria could antagonize the toxicity of bacterial pathogens, this effect being EPS and biological marker dependent. Significance and Impact of the Study: This work allows gaining insight about the mechanisms that probiotics could exert to improve the host health.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Criotecnología de Alimento

Fermented Dairy Foods: Impact on Intestinal Microbiota and Health-Linked Biomarkers

The intake of fermented foods is gaining increasing interest due to their health-promoting benefits. Among them, fermented dairy foods have been associated with obesity prevention, and reduction of the risk of metabolic disorders and immune-related pathologies. Fermented foods could lead to these health benefits by providing the consumer with both easily metabolizable nutrients and beneficial microorganisms. Our aim was to evaluate the relationship between the consumption of fermented dairy products and the intestinal microbiota, serum lipid profile, and the pro-oxidant/inflammatory status. 130 healthy adults were evaluated. Dietary fermented food intake was assessed by an annual food frequency questionnaire (FFQ), including 26 fermented dairy products. Levels of the major phylogenetic types of the intestinal microbiota were determined by qPCR, and concentration of fecal short chain fatty acids were assessed by gas chromatography. Serum glucose and lipid profile, as well as serum malondialdehyde (MDA), C-reactive protein (CRP), and leptin levels were determined by standardized protocols. Among fermented dairy foods, natural yogurt, sweetened yogurt and matured/semi-matured cheese were the most consumed. While natural yogurt consumers showed increased fecal levels of Akkermansia with respect to non-consumers, sweetened yogurt intake was associated to lower levels of Bacteroides. Serum levels of CRP were also significantly reduced in yogurt consumers. Our results underline the interest in exploring the potential effects of the different yogurt types and the role the microbiota may play in such effects

Exopolysaccharides produced by Lactobacillus and Bifidobacterium strains abrogate in vitro the cytotoxic effect of bacterial toxins on eukaryotic cells

Aims: To evaluate the capability of the exopolysaccharides (EPS) produced by lactobacilli and bifidobacteria from human and dairy origin to antagonize the cytotoxic effect of bacterial toxins. Methods and Results: The cytotoxicity of Bacillus cereus extracellular factors on Caco-2 colonocytes in the presence/absence of the EPS was determined by measuring the integrity of the tissue monolayer and the damage to the cell membrane (extracellular lactate dehydrogenase activity). Additionally, the protective effect of EPS against the haemolytic activity of the streptolysin-O was evaluated on rabbit erythrocytes. The EPS produced by Bifidobacterium animalis ssp. lactis A1 and IPLA-R1, Bifidobacterium longum NB667 and Lactobacillus rhamnosus GG were able to counteract the toxic effect of bacterial toxins on the eukaryotic cells at 1 mg ml-1 EPS concentration. The EPS A1 was the most effective in counteracting the effect of B. cereus toxins on colonocytes, even at lower doses (0.5 mg ml-1), whereas EPS NB667 elicited the highest haemolysis reduction on erythrocytes. Conclusions: The production of EPS by lactobacilli and bifidobacteria could antagonize the toxicity of bacterial pathogens, this effect being EPS and biological marker dependent. Significance and Impact of the Study: This work allows gaining insight about the mechanisms that probiotics could exert to improve the host health.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Criotecnología de Alimento

Mosaic-like sequences containing transposon, phage, and plasmid elements among Listeria monocytogenes plasmids

Sequencing of plasmid pLM33 from the food isolate Listeria monocytogenes Lm1 revealed a molecule of 32,307 bp with a G+C content of 36.2%. The plasmid displays a mosaic pattern of identities common to several closely related L. monocytogenes plasmids isolated from food and clinical source

Characteristics of carbonated fermented milk and survival of probiotic bacteria

The carbonation of pasteurised milk was evaluated as a method for improving bacterial viability in fermented milk added with probiotic bacteria (Lactobacillus acidophilus and/or Bifidobacterium bifidum). The behaviour of microorganisms during fermentation and cold storage, and the biochemical and sensory properties of the products were assessed. In AT (Streptococcus thermophilus/L. acidophilus) and ABT (S. thermophilus/L. acidophilus/B. bifidum) products, the fermentation times to decrease the pH to 5 were significantly lowered when CO2 or lactic acid was added to milk. The higher acidity levels of carbonated (as a result of production of carbonic acid) and lactic acidified samples enhanced growth and metabolic activity of the starter during fermentation and was the reason for this reduction in incubation time. Cell counts of S. thermophilus, L. acidophilus and B. bifidum gradually decreased through the cold storage of carbonated and non-acidified fermented milks, although the counts were always higher than 106 viable cells g-1. The CO2 did not exert any influence on the viability of S. thermophilus and L. acidophilus in AT fermented milks stored at 4°C but the presence of B. bifidum and CO2 in ABT-type products was associated with lower viability of L. acidophilus during the refrigerated storage. The higher acetate concentrations of ABT products made with non-acidified milk as compared with the carbonated products could have contributed to major survival of L. acidophilus in the former. The use of milk acidified with CO2 had no detrimental effects on the sensory properties of ABT fermented milks. Therefore, we concluded that the carbonation of pasteurised milk prior to the starter addition could be satisfactorily used to reduce the manufacture time of fermented milk.Fil: Vinderola, Celso Gabriel. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Prog.de Lactología Industrial; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gueimonde, M.. Consejo Superior de Investigaciones Científicas. Instituto Superior de Productos Lacteos de Asturias; EspañaFil: Delgado, T.. Consejo Superior de Investigaciones Científicas. Instituto Superior de Productos Lacteos de Asturias; EspañaFil: Reinheimer, Jorge Alberto. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Prog.de Lactología Industrial; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Reyes Gavilán, C. G. de los. Consejo Superior de Investigaciones Científicas. Instituto Superior de Productos Lacteos de Asturias; Españ

Intestinal microbiota development in preterm neonates and effect of perinatal antibiotics

Objectives To assess the establishment of the intestinal microbiota in very low birthweight preterm infants and to evaluate the impact of perinatal factors, such as delivery mode and perinatal antibiotics. Study design We used 16S ribosomal RNA gene sequence-based microbiota analysis and quantitative polymerase chain reaction to evaluate the establishment of the intestinal microbiota. We also evaluated factors affecting the microbiota, during the first 3 months of life in preterm infants (n = 27) compared with full-term babies (n = 13). Results Immaturity affects the microbiota as indicated by a reduced percentage of the family Bacteroidaceae during the first months of life and by a higher initial percentage of Lactobacillaceae in preterm infants compared with full term infants. Perinatal antibiotics, including intrapartum antimicrobial prophylaxis, affects the gut microbiota, as indicated by increased Enterobacteriaceae family organisms in the infants. Conclusions Prematurity and perinatal antibiotic administration strongly affect the initial establishment of microbiota with potential consequences for later health