Probiotic
A PCR method for detection of bifidobacteria in raw milk and raw milk cheese: comparison with culture-based methods
Delcenserie V., Bechoux N., China B., Daube G., Gavini
Bifidobacteria are well known for their beneficial effects on health and are used as probiotics in food and pharmaceutical products. As they form one of the most important groups in both human and animal feces, their use as fecal indicator organisms in raw milk products has recently been proposed. Bifidobacteria species isolated in humans are different from those isolated in animals. It should therefore be possible to determine contamination origin (human or animal). A method of detecting the Bifidobacterium genus was developed by PCR targeting the hsp60 gene. The genus Bifidobacterium was identified by PCR amplification of a 217-bp hsp60 gene fragment. The degenerated primer pair specific to the Bifidobacterium genus used was tested for it specificity on 127 strains. Sensitivity was measured on artificially contaminated samples. Food can however be a difficult matrix for PCR testing since it contains PCR inhibitors. So an internal PCR control was used. An artificially created DNA fragment of 315 bp was constructed. The PCR detection method was tested on raw milk and cheese samples and compared with three culture-based methods, which comprised enrichment and isolation steps. The enrichment step used Brain Heart Infusion medium with propionic acid, iron citrate, yeast extract, supplemented with mupirocin (BHMup) or not (BH) and the isolation step used Columbia blood agar medium, supplemented with mupirocin (CMup) or not (C). The method using mupirocin at both enrichment and isolation steps and the PCR method performed from the culture in BHMup enrichment medium were shown to be the most efficient. No significant difference was observed in raw milk samples between PCR from BHMup and the culture-based method BHMup/CMup, while a significant difference was noticed between the same methods in raw milk cheese samples, which would favor using PCR.
The results suggested that PCR on the hsp60 gene was convenient for a rapid detection of bifidobacteria in raw milk and raw milk cheese samples and that bifidobacteria always present throughout raw milk cheese production could be efficiently used as fecal indicators.
J Microbiol Methods. 2005 Apr;61(1):55-67
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Probiotics and Prebiotics: Scientific Aspects
Tannock G.W.
Probiotics are products aimed at delivering living bacterial cells to the gut ecosystem of humans and other animals, whereas prebiotics are non-digestible carbohydrates delivered in food to the large bowel to provide fermentable substrates for selected bacteria. Food scientists and nutritionists have accepted, relatively uncritically, the concepts underlying the use of probiotics and prebiotics in the promotion of health. Microbiologists and medical practitioners have viewed these products more sceptically. Much more scientific and medical validation of probiotic/prebiotic use is required. This will entail the use of sophisticated analytical methodologies. Knowledge of the gut microbiota has increased dramatically during the past decade thanks largely to the results obtained from the application of nucleic acid-based methodologies. Because of the availability of improved technologies, detailed studies of the two principal kinds of probiotic/prebiotic bacteria, members of the genera Lactobacillus and Bifidobacterium, can be made. While well-established scientists continue to make important contributions to probiotic/prebiotic research, it is notable that younger scholars are playing a vital role in developing scientific concepts related to the field. Several of these emerging leaders have contributed chapters to this book that therefore represents a state-of-the-art compendium of fundamental science related to early 21st century probiotic/prebiotic research.
On Horizon Press
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Importance of S-layer proteins in probiotic activity of Lactobacillus acidophilus M92
Frece J., Kos B., Svetec I.K., Zgaga Z., Mrsa V., Suskov
Aims: To investigate the functional role of surface layer proteins (S-layer) in probiotic strain Lactobacillus acidophilus M92, especially its influence on adhesiveness to mouse ileal epithelial cells.
Methods and Results: Sodium dodecyl sulphate polyacrylamide gel electrophoresis of cell surface proteins revealed the presence of potential surface layer (S-layer) proteins, ca at 45 kDa in L. acidophilus M92. Southern blot with pBK1 plasmid, containing slpA gene, gave a positive signal, suggesting that L. acidophilus M92 has a slpA gene coding for the S-layer proteins. S-layer proteins of this strain are present during all phases of growth. The S-layer proteins appeared when cells treated with 5 mol l(-1) LiCl were allowed to grow again. Removal of the S-layer proteins reduced adhesion of L. acidophilus M92 to mouse ileal epithelial cells. Furthermore, the viability of cells without S-layer were reduced in simulated gastric juice at low pH range (2, 2.5, 3) and simulated pancreatic juice with bile salts (1.5 and 3 g l(-1)). S-layer proteins of L. acidophilus M92 were resistant to pepsin and pancreatin, in contrast, the treatment with proteinase K led to a significant proteolysis of the S-layer proteins.
Conclusions: These results demonstrated functional role of S-layer; it is responsible for adhesiveness of Lactobacillus acidophilus M92 to mouse ileal epithelial cells and has a protective role for this strain. Significance and Impact of the Study: S-layer proteins have an important role in the establishment of probiotic strain Lactobacillus acidophilus M92 in the gastrointestinal tract.
J Appl Microbiol. 2005 Feb;98(2):285-292
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Gut flora-based therapy in liver disease? The liver cares about the gut.
Solga S.F., Diehl A.M.
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Probiotics: An Emerging Therapy
O'Sullivan G.C., Kelly P., O'Halloran S., Collins C., Collins J.K., Dunne C., Shanahan F.
There is considerable clinical interest in the utility of probiotic therapy - the feeding of (live) non-pathogenic bacteria, originally derived from the alimentary tract, for disease treatment or health promotion. The microflora of the gastrointestinal tract is essential for mucosal protection, for immune education and for metabolism of fecal residue. Physiological disturbances of these processes, when they occur, result from: i) alteration of a microbial ecosystem, originally conserved by evolution; ii) reduced consumption of microorganisms; iii) invasion of pathogens; or iv) modern interventions. Recent data support the use of proven probiotic organisms in prevention and treatment of flora-related gastrointestinal disorders including inflammatory bowel disease, infectious and antibiotic related diarrheas, and post-resection disorders including pouchitis. Therapeutic activity of probiotic bacteria can be due to competition with patho-gens for nutrients and mucosal adherence, production of antimicrobial substances, and modulation of mucosal immune functions. Although a promising treatment, controlled clinical trials are necessary to validate the benefit of probiotics.
Curr Pharm Des. 2005;11(1):3-10
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Probiotic research in Australia, New Zealand and the Asia-pacific region
Crittenden R., Bird A.R., Gopal P., Henriksson A., Lee Y.K., Playne M.J.
This paper provides an overview of probiotic research within Australia, New Zealand and a number of Asian countries, and lists scientists in the Asia-Pacific region involved in various aspects of probiotic research and development.
Curr Pharm Des. 2005;11(1):37-53
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Probiotics and prebiotics in clinical practice
Broussard E.K., Surawicz C.M.
Probiotics are living organisms that have a beneficial therapeutic effect on the host when ingested. The bacteria Lactobacillus GG and the yeast Saccharomyces boulardii have been shown in controlled trials to prevent antibiotic-associated diarrhea. Prebiotics are non-living, indigestible polysaccharides metabolized in the intestine that induce physical and bacteriologic musocal modifications. Rather than introducing exogenous bacteria into the intestinal millieu, prebiotics stimulate certain indigenous bacteria already resident in the gut.
Nutr Clin Care. 2004 Jul-Sep;7(3):104-13
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Major depressive disorder: probiotics may be an adjuvant therapy
Logan A.C., Katzman M.
Major depressive disorder (MDD) is an extremely complex and heterogeneous condition. Emerging research suggests that nutritional influences on MDD are currently underestimated. MDD patients have been shown to have elevated levels of pro-inflammatory cytokines, increased oxidative stress, altered gastrointestinal (GI) function, and lowered micronutrient and omega-3 fatty acid status. Small intestinal bacterial overgrowth (SIBO) is likely contributing to the limited nutrient absorption in MDD. Stress, a significant factor in MDD, is known to alter GI microflora, lowering levels of lactobacilli and bifidobacterium. Research suggests that bacteria in the GI tract can communicate with the central nervous system, even in the absence of an immune response. Probiotics have the potential to lower systemic inflammatory cytokines, decrease oxidative stress, improve nutritional status, and correct SIBO. The effect of probiotics on systemic inflammatory cytokines and oxidative stress may ultimately lead to increased brain derived neurotrophic factor (BDNF). It is our contention that probiotics may be an adjuvant to standard care in MDD.
Med Hypotheses. 2005;64(3):533-8.
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Probiotics and gastrointestinal diseases
Sullivan A., Nord C.E.
There is increasing evidence indicating health benefits by consumption of foods containing microorganisms, i.e. probiotics. A number of clinical trials have been performed to evaluate the effects in the prevention and treatment of gastrointestinal diseases caused by pathogenic microorganisms or by disturbances in the normal microflora. Gastrointestinal infections caused by Helicobacter pylori, traveller's diarrhoea, rotavirus diarrhoea, antibiotic-associated diarrhoea (AAD) and Clostridium difficile-induced diarrhoea are conditions that have been studied. There are also studies performed on the preventive effect of probiotics on radiation-induced diarrhoea and diarrhoea in tube-fed patients. Inflammatory bowel disease and irritable bowel syndrome, two idiopathic conditions where alterations in the normal microflora have been implicated as responsible for initiation, are two further areas where the use of probiotics has been regarded as promising. The results from clinical studies have not been conclusive in that the effects of probiotics have been strain-dependent and different study designs have been used. Treatment of acute diarrhoea in children and prevention of AAD are the two most justified areas for the application of probiotics.
J Intern Med. 2005 Jan;257(1):78-92.
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