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PubMed2003

Caseinphosphopeptides in milk and fermented milk do not affect calcium metabolism acutely in postmenopausal women.

BACKGROUND: Caseinphosphopeptides (CPPs) are formed in food processing or during digestion in the gastrointestinal tract. CPPs prevent the formation of insoluble calcium salts; thus, the hypothesis is that CPPs increase the absorption of calcium. OBJECTIVE: We examined the effect of additional caseinphosphopeptides in milk and fermented milk on acute calcium metabolism by measuring intact PTH (iPTH), ionized calcium (iCa), total calcium (Ca) and phosphate (P) from serum, and 24-hour calcium from urine (U-Ca). METHODS: The study consisted of two separate parts, both applying a double-blind randomized crossover study with two interventions, in nine postmenopausal women. The acute effect on calcium metabolism was analysed by measuring iPTH, iCa, Ca and P from serum during the first six hours after the administration of the study milks. U-Ca was analysed 24 hours prior to the study and 0, 2, 4, 6, 12 and 24 hours after the administration of the study milks. The study included two parts, both consisting of two study days with a one-week washout period in between. In the first part the effect of control milk and CPP-enriched milk was measured. The second part evaluated the effect of fermentation by giving subjects milk or fermented milk, both enriched with CPPs. RESULTS: In the first part of the study there were no statistically significant differences in iPTH, iCa, Ca, P or U-Ca between the groups receiving control milk compared to CPP-containing milk. There was no difference in the AUC((0-6)) of iCa and iPTH. In the second part, fermentation did not affect calcium metabolism, when results from the CPP-enriched milk and CPP-enriched fermented milk groups were compared. CONCLUSION: One gram of caseinphosphopeptides does not affect calcium metabolism acutely in postmenopausal women.

Aged↗

PubMed2000

Control of foodborne pathogens during sufu fermentation and aging.

Control of the foodborne pathogens Escherichia coli O157:H7, Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes during sufu fermentation was evaluated. Before fermentation, pathogens were inoculated onto tofu (substrate for sufu) at 5 log cfu/g or 3 log cfu/g, and starter culture (Actinomucor elegans) was inoculated at 3 log cfu/g. After 2 days of fermentation at 30 degrees C, the four pathogens reached 7 to 9 log cfu/g, and the mold count reached 6 to 7 log cfu/g. After fermentation, sufu samples were aged in a solution of 10% alcohol + 12% NaCl. After 1 month of aging, the total bacterial count was 6 to 7 log cfu/g, but all foodborne pathogens and mold were reduced to nondetectable levels. The total bacterial count decreased after aging for 2 months and 3 months, but the differences were not significant (P > 0.05) compared with the count after 1 month. Microorganism in experimental sufu from different aging periods and in commercial sufu were compared. A total of 270 isolates were purified and identified by the BBL Crystal Identification System. From the experimental sufu samples, 49 Bacillus spp. (20.4%), 167 Enterococcus spp. (69.6%), 6 Shewanella putrefaciens (2.4%), and 18 miscellaneous gram-negative bacilli (7.5%) were identified. From commercial sufu samples, 17 Bacillus spp. (56.7%), 2 Enterococcus durans (6.7%), 5 miscellaneous gram-negative bacilli (16.7%), 5 Corynbacterium aquaticum (16.7%), and 1 Shewanella putrefaciens (3.3%) were obtained. Although the longer aging period did not significantly decrease the total bacterial count, it may help in the development of sufu flavor. This study showed that sufu fermentation and aging can control common foodborne pathogens, so sufu is a safe product even though its preparation does not include pasteurization.

Biotechnology↗

PubMed1976

Photodynamic action of thiopyronine on the respiration and fermentation in yeast.

The efficiency of photodynamic treatment with thiopyronine (TP) on the respiration and fermentation of yeast cells, on the metabolic oxygen uptake of isolated mitochondrial preparations from yeast, and on the enzyme activity of alcohol dehydrogenase (ADH) in vivo and in vitro were studied. Respiration was inactivated by treatment with TP and visible light more at the initial stage than was the fermentation. Isolated mitochondria and ADH in vitro were not as sensitive to treatment as were respiration and fermentation in vivo. Inactivation patterns of respiration and fermentation in vivo showed that the inactivation was not due to damage to the DNA. The hindrance of respiration and fermentation might be one of main causes of cell-death resulting from photodynamic treatment.

Alcohol Oxidoreductases↗

PubMed2000

Control of foodborne pathogens during sufu fermentation and aging.

Control of the foodborne pathogens Escherichia coli O157:H7, Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes during sufu fermentation was evaluated. Before fermentation, pathogens were inoculated onto tofu (substrate for sufu) at 5 log cfu/g or 3 log cfu/g, and starter culture (Actinomucor elegans) was inoculated at 3 log cfu/g. After 2 days of fermentation at 30 degrees C, the four pathogens reached 7 to 9 log cfu/g, and the mold count reached 6 to 7 log cfu/g. After fermentation, sufu samples were aged in a solution of 10% alcohol + 12% NaCl. After 1 month of aging, the total bacterial count was 6 to 7 log cfu/g, but all foodborne pathogens and mold were reduced to nondetectable levels. The total bacterial count decreased after aging for 2 months and 3 months, but the differences were not significant (P > 0.05) compared with the count after 1 month. Microorganism in experimental sufu from different aging periods and in commercial sufu were compared. A total of 270 isolates were purified and identified by the BBL Crystal Identification System. From the experimental sufu samples, 49 Bacillus spp. (20.4%), 167 Enterococcus spp. (69.6%), 6 Shewanella putrefaciens (2.4%), and 18 miscellaneous Gram-negative bacilli (7.5%) were identified. From commercial sufu samples, 17 Bacillus spp. (56.7%), 2 Enterococcus durans (6.7%), 5 miscellaneous Gram-negative bacilli (16.7%), 5 Corynbacterium aquaticum (16.7%), and 1 Shewanella putrefaciens (3.3%) were obtained. Although the longer aging period did not significantly decrease the total bacterial count, it may help in the development of sufu flavor. This study showed that sufu fermentation and aging can control common foodborne pathogens, so sufu is a safe product even though its preparation does not include pasteurization.

Bacteria↗

PubMed2004

The microbiology of cocoa fermentation and its role in chocolate quality.

The first stage of chocolate production consists of a natural, seven-day microbial fermentation of the pectinaceous pulp surrounding beans of the tree Theobroma cacao. There is a microbial succession of a wide range of yeasts, lactic-acid, and acetic-acid bacteria during which high temperatures of up to 50 degrees C and microbial products, such as ethanol, lactic acid, and acetic acid, kill the beans and cause production of flavor precursors. Over-fermentation leads to a rise in bacilli and filamentous fungi that can cause off-flavors. The physiological roles of the predominant micro-organisms are now reasonably well understood and the crucial importance of a well-ordered microbial succession in cocoa aroma has been established. It has been possible to use a synthetic microbial cocktail inoculum of just 5 species, including members of the 3 principal groups, to mimic the natural fermentation process and yield good quality chocolate. Reduction of the amount of pectin by physical or mechanical means can also lead to an improved fermentation in reduced time and the juice can be used as a high-value byproduct. To improve the quality of the processed beans, more research is needed on pectinase production by yeasts, better depulping, fermenter design, and the use of starter cultures.

Acetic Acid↗

PubMed2000

Fermentation of carbohydrates and yield of microbial protein in mixed cultures of rabbit caecal microorganisms.

Fermentation pattern and yields of microbial protein were investigated in cultures of the rabbit caecal contents supplied with glucose, xylose, starch, pectin and xylan. Rabbits at the age of 4 weeks (before weaning) and 3 months were slaughtered, their caecal contents added at 1.1% to growth media and incubated anaerobically at 39 degrees C for 18 h. Caecal microorganisms of 4-week-old rabbits produced no methane and caproate, less butyrate, but more propionate than microorganisms of 3-month-old rabbits. In both groups of rabbits, fermentation of xylose produced significantly more propionate and less butyrate than fermentation of glucose. More propionate and less acetate was formed from starch than from pectin. In caecal cultures from 4-week-old rabbits with pectin, the molar percentages of acetate was significantly higher and percentages of other short-chain fatty acids (SCFA) lower than in cultures with starch or xylan. In cultures from 3-month-old rabbits, fermentation of pectin and xylan produced similar SCFA profiles, different from SCFA molar composition in cultures with starch. Average production of microbial protein was 129 mg per 1 g of carbohydrate digested (range 110 to 141 mg/g). Protein yields were the same on glucose and xylose, but nonsignificantly higher on starch than on pectin and xylan. It can be concluded that the characteristics of substrate affected fermentation pattern in mixed cultures of rabbit caecal microorganisms. Substrate effects on protein yields were not statistically significant, due to high variation.

Age Factors↗

PubMed2006

Effects of tea saponins on in vitro ruminal fermentation and growth performance in growing Boer goat.

Two experiments were conducted to investigate the effects of tea saponins (TS) on in vitro ruminal fermentation and growth performance in growing Boer goats. In Experiment 1, the Reading Pressure Technique (RPT) system was used to investigate the effect of addition of TS (0, 0.2, 0.4 and 0.8 mg/ml) on the ruminal fermentation in vitro. The 24h gas production and methane emission were significantly decreased when 0.4 or 0.8mg TS was included, suggesting that the TS could inhibit the release of methane. Compared to the control, the TS had little effect on pH values and the concentration of total volatile fatty acids in the ruminal fluids. However, the fermentation patterns were changed, with lower acetate and higher proportions of propionate when TS was added. Ammonia-N concentration and protozoal counts were significantly reduced, while microbial protein yield was increased by the TS addition, suggesting that the TS could modify the ruminal fermentation. In Experiment 2, 27 growing Boer goats were used to evaluate the effects of the TS addition on growth performance. The animals received the same basal diets, and added TS at levels of 0 (C), 3 g (T1) and 6 g (T2) per day. The experiment lasted for 60 days with the first 15 days for adaptation. Blood samples were obtained by jugular venipuncture before the morning feeding on the final day of the experiment. During the whole periods, dry matter intake, average daily gain and feed efficiency in T1 were higher than in the other two. Serum total protein, albumin, high density lipoprotein cholesterol, Ca and P and alkaline phosphatase levels were higher in group T1 than in C and T2, whereas the blood urea nitrogen, creatinine and total cholesterol were lower in the TS-added groups. The concentrations of glucose, glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase were not affected by the TS. From the results obtained in this study, it is inferred that the TS could modify the ruminal fermentation and that proper doses of TS may have potential in improving the animal growth performance, whereas at high doses, it may have adverse effects on animal production.

Animals↗

PubMed1979

Fermentations by saccharolytic intestinal bacteria.

Most nonsporing anaerobes of the intestinal tract use the Embden-Meyerhof-Parnas scheme to ferment carbohydrates. Almost all of them oxidize pyruvate, the key fermentation intermediate, to acetyl coenzyme A and CO2 with reduction of a low-potential electron acceptor. H2 is formed from the low potential acceptor or from NADH. Pyruvate is a precursor of lactate, and phosphoenolpyruvate is a precursor of succinate and propionate. Ethanol, acetate, and butyrate are formed from acetyl coenzyme A. Formate is produced by reduction of CO2 by Ruminococcus albus. Heme is required by human Bacteroides for the formation of succinate and, in the presence of vitamin B12, propionate. A fermentation equation derived from the concentration of volatile acids found in human feces suggests that the fermentation in the large intestine is similar to the rumen fermentation.

Actinomycetales↗

PubMed1992

Survival of bifidobacteria ingested via fermented milk during their passage through the human small intestine: an in vivo study using intestinal perfusion.

The ability of a strain of Bifidobacterium sp to survive passage through the upper gastrointestinal tract when ingested in fermented milk was investigated in six fasting healthy adults by using in vivo ileal perfusion. After ingestion of 10.0 +/- 0.5 log10 bifidobacteria in 400 g fermented milk, ileal flow of bifidobacteria increased significantly and reached a maximum of 8.8 +/- 0.2 log10 bifidobacteria/h 1.7 +/- 0.4 h after ingestion of fermented milk. The average number of bifidobacteria recovered from the terminal ileum during the 8 h after fermented-milk ingestion was 9.0 +/- 0.1 log10 and constituted 23.5 +/- 10.4% of the number ingested. These results indicate that in healthy adults Bifidobacterium sp survive transit through the gastrointestinal tract when ingested in fermented milk. Further studies are needed to investigate the behavior of these exogenous bacteria in the colonic lumen and to explore their effects on the physiology of the human gastrointestinal tract.

Adult↗

PubMed2001

Probiotic bacteria in fermented foods: product characteristics and starter organisms.

Probiotic bacteria are sold mainly in fermented foods, and dairy products play a predominant role as carriers of probiotics. These foods are well suited to promoting the positive health image of probiotics for several reasons: 1) fermented foods, and dairy products in particular, already have a positive health image; 2) consumers are familiar with the fact that fermented foods contain living microorganisms (bacteria); and 3) probiotics used as starter organisms combine the positive images of fermentation and probiotic cultures. When probiotics are added to fermented foods, several factors must be considered that may influence the ability of the probiotics to survive in the product and become active when entering the consumer's gastrointestinal tract. These factors include 1) the physiologic state of the probiotic organisms added (whether the cells are from the logarithmic or the stationary growth phase), 2) the physical conditions of product storage (eg, temperature), 3) the chemical composition of the product to which the probiotics are added (eg, acidity, available carbohydrate content, nitrogen sources, mineral content, water activity, and oxygen content), and 4) possible interactions of the probiotics with the starter cultures (eg, bacteriocin production, antagonism, and synergism). The interactions of probiotics with either the food matrix or the starter culture may be even more intensive when probiotics are used as a component of the starter culture. Some of these aspects are discussed in this article, with an emphasis on dairy products such as milk, yogurt, and cheese.

Bifidobacterium↗

PubMed2001

Prebiotic digestion and fermentation.

Prebiotics, as currently conceived of, are all carbohydrates of relatively short chain length. To be effective they must reach the cecum. Present evidence concerning the 2 most studied prebiotics, fructooligosaccharides and inulin, is consistent with their resisting digestion by gastric acid and pancreatic enzymes in vivo. However, the wide variety of new candidate prebiotics becoming available for human use requires that a manageable set of in vitro tests be agreed on so that their nondigestibility and fermentability can be established without recourse to human studies in every case. In the large intestine, prebiotics, in addition to their selective effects on bifidobacteria and lactobacilli, influence many aspects of bowel function through fermentation. Short-chain fatty acids are a major product of prebiotic breakdown, but as yet, no characteristic pattern of fermentation acids has been identified. Through stimulation of bacterial growth and fermentation, prebiotics affect bowel habit and are mildly laxative. Perhaps more importantly, some are a potent source of hydrogen in the gut. Mild flatulence is frequently observed by subjects being fed prebiotics; in a significant number of subjects it is severe enough to be unacceptable and to discourage consumption. Prebiotics are like other carbohydrates that reach the cecum, such as nonstarch polysaccharides, sugar alcohols, and resistant starch, in being substrates for fermentation. They are, however, distinctive in their selective effect on the microflora and their propensity to produce flatulence.

Cathartics↗

PubMed1995

Use of HT-29, a cultured human colon cancer cell line, to study the effect of fermented milks on colon cancer cell growth and differentiation.

Epidemiological and in vivo and in vitro experimental studies have suggested that fermented milks may interfere with the emergence and/or the development of colon cancer. The results, however, remain inconclusive. This prompted us to develop a new approach based on the use of HT-29, a cultured human colon cancer cell line, to study at the cellular level the effect of fermented milks on colon cancer cell growth and differentiation characteristics. Undifferentiated HT-29 cells have been grown in the continuous presence of milks fermented by one of the following bacterial populations: Lactobacillus helveticus, Bifidobacterium, L.acidophilus or a mix of Streptococcus thermophilus and L. bulgaricus. Penicillin G was added to the cell culture medium, resulting in a complete blockade of bacterial growth without significant effect on bacterial viability. One out of the four bacteria species studied, namely L.acidophilus, was without effect on both cell growth and differentiation. The three other bacterial strains induced a significant, although variable, reduction in the growth rate of HT-29 cells, which resulted in a 10-50% decrease in the cell number at steady-state (i.e. at cell confluency). The most efficient strains in lowering the HT-29 growth rate were L. helveticus and Bifidobacterium. Concomitantly, the specific activities of dipeptidyl peptidase IV (DPP IV), a sensitive and specific marker of HT-29 cell differentiation, and that of three other brush border enzymes (sucrase, aminopeptidase N and alkaline phosphatase) were significantly increased, thus suggesting that these cells may have entered a differentiation process. Altogether, these results indicate that the use of cultured colon cancer cells may be a useful tool to further study the effect of fermented milks on colon cancer and that bacterial strains may exert a different and specific effect on cancer cell growth and differentiation when used in fermented milk products.

Animals↗

PubMed2006

Effect of dietary resistant starch and protein on colonic fermentation and intestinal tumourigenesis in rats.

Protein as well as starch is fermented in the colon, but the interaction between protein and starch fermentation and the impact on colonic oncogenesis is unknown. High-protein diets increase delivery of protein to the colon and might promote oncogenesis through generation of toxic products. We investigated the interaction of resistant starch (RS) with digestion-resistant potato protein (PP) on colonic fermentation events and their relationship to intestinal tumourigenesis. Male Sprague-Dawley rats were fed an AIN-76A-based diet for 4 weeks and intestinal neoplasms were induced by azoxymethane. Experimental diets included the following: no added RS or PP, 10% high amylose maize starch (source of RS) replacing digestible starch, 15% PP replacing casein and 10% high amylose maize starch+15% PP. Rats were maintained on diets until killed at 30 weeks. Feeding RS significantly increased short-chain fatty acid (SCFA) levels (P<0.001) in the caecum and colon. Importantly, butyrate concentration was significantly increased in the distal colon with RS (P<0.001). Feeding PP increased protein fermentation products, but this effect was reduced by adding RS to the diet. Intestinal neoplasms and colorectal adenocarcinomas were reduced by feeding RS (P<0.01) regardless of whether PP was fed, whereas PP alone increased the incidence and number of small intestinal neoplasms including the adenocarcinomas (P<0.01). In conclusion, RS altered the colonic luminal environment by increasing the concentration of SCFAs including butyrate and lowering production of potentially toxic protein fermentation products. These effects of RS not only protected against intestinal tumourigenesis but also ameliorated the tumour-enhancing effects of feeding indigestible protein.

Animals↗

PubMedDate not supplied

In vitro and in vivo effects of three bismuth compounds on fermentation by colonic bacteria.

Three bismuth compounds (tripotassium dicitrate bismuthate, bismuth subsalicylate, and bismuth subnitrate) were tested in vitro and in vivo for their effect on fermentation by colonic bacteria. The studies in vitro were done with use of a technique designed to determine the effect of each one of the bismuth compounds on the fermentation of several stool samples that had been mixed with lactose as additional fermentable substrate (fermentation of lactose-enriched stools, FLES). The three bismuth compounds reduced FLES significantly in 47 (81%) of 58 of the stool samples used to test their effect. Bismuth subsalicylate, which reduced FLES in 10 of 10 stool samples, showed the greatest reduction (mean reduction, 74%; P less than .0001). The in vivo studies, done in six flatulent patients, showed significant reduction (P less than .01) of colonic fermentation of ingested raffinose by oral bismuth subnitrate given for 8 days.

Adolescent↗

PubMed1988

Nutritive value of whole soybeans fermented with Aspergillus oryzae or Rhizopus oligosporus as evaluated by neonatal pigs.

Two experiments were conducted to evaluate the nutritive effects of heated whole soybeans fermented with the mold Aspergillus oryzae (AOS) or Rhizopus oligosporus (ROS) in diets fed to neonatal pigs from 1 to 22 d of age. In experiment 1, either soybean meal or heated whole soybeans fermented with ROS replaced 75% of the dried skim milk protein. The average daily gain (ADG) and gain-feed (G-F) ratio of pigs fed the diet containing 100% milk protein were greater than those of pigs fed the diets containing either soybean meal or ROS. In experiment 2, heated nonfermented whole soybeans (HUS) or heated whole soybeans fermented with either AOS or ROS replaced 50% of the milk protein in isonitrogenous and isoenergetic diets. Proximate and amino acid analyses of HUS and the fermented soybean products, AOS and ROS were similar. Pigs fed a diet containing either HUS or AOS had greater (P less than 0.05) mean ADG and G-F ratios than pigs fed the diet containing ROS. Apparent biological value, apparent net protein utilization and digestible and metabolizable energy utilization were similar for all dietary treatments. In conclusion, the protein and energy values of whole soybeans were not improved by fermentation with ROS or AOS compared to nonfermented heated whole soybeans, soybean meal or dried skim milk in diets fed to neonatal pigs.

Amino Acids↗

PubMed1993

In vitro production of short-chain fatty acids by bacterial fermentation of dietary fiber compared with effects of those fibers on hepatic sterol synthesis in rats.

The aim of this study was to determine the effects of fiber feeding on short-chain fatty acid (SCFA) production in laboratory rats and in an in vitro fermentation model using fecal inocula from rats adapted to a high fiber diet. In addition, the effect of fiber intake on endogenous sterol synthesis was evaluated. Twenty male Sprague-Dawley rats were divided into four groups and fed a control or 30% fiber diet (cellulose, pectin or pea fiber) for 4 wk. In vitro fermentation was compared with measurements of cecal SCFA content of fiber-adapted rats. Sterol synthesis in isolated hepatocytes was determined in groups of five to seven rats fed 15% dietary fiber for 4 wk. Cellulose was poorly fermented in both the in vitro and in vivo experiments. Pectin fermentation produced high levels of propionate, whereas pea fiber was associated with notable butyrate production. Adaptation to pectin produced seven times more SCFA in rat cecal contents (515 +/- 78 mumol) in comparison to a fiber-free diet (70.6 +/- 4.9 mumol), with similar results observed in vitro. Sterol synthesis in hepatocytes of rats fed pectin was significantly greater than in those of control or cellulose-fed rats. Despite significantly higher rates of SCFA production in pectin-fed rats, cholesterol synthesis was not inhibited, suggesting that SCFA are not the cholesterol-lowering factor of highly fermentable fiber sources.

Acetates↗

PubMed1996

Lactitol enhances short-chain fatty acid and gas production by swine cecal microflora to a greater extent when fermenting low rather than high fiber diets.

The study was conducted to determine if the response of swine cecal microflora to lactitol (beta-D-galactopyranosyl-(1-->4)-D-sorbitol; 3 mmol/L) varies when fermenting low (LF) or high fiber (HF) predigested diets. The inoculum was collected from four sows fitted with cecal cannulas, pooled, buffered and dispensed in 27 vessels under anaerobic conditions. The LF or HF predigested diets were used as substrate in two separate experiments. In each trial nine vessels were used as controls (C) without feed addition, nine received predigested feed (LF or HF) and the remaining nine vessels received the same amount of feed with the supplementation of lactitol (LF+L or HF+L). Lactitol (L) significantly lowered pH and the acetic to propionic acid ratio in the first 8 h of fermentation in both experiments (P < 0.05). At 4 and 8 h, the addition of lactitol reduced ammonia by 100 and 84% in LF+L and by 56 and 38% in HF+L (P < 0.05). In addition, LF+L and HF+L diets gave higher short-chain fatty acid energy yields by 70 and 40% than LF and HF, respectively (P < 0.05). Two bacterial growth models (logistic and Gompertz) were tested to fit gas production data. The Gompertz equation provided a better fit than the logistic model to gas production data for both LF and HF experiments. Lactitol reduced culture lag time in both experiments by approximately 50%, but it increased gas production rate and maximum gas production by approximately 60% only when the microflora was fermenting the LF predigested diet (P < 0.05). No difference in the duration of the exponential phase due to lactitol was observed in either experiment. Our results indicate that lactitol may be an interesting additive to animal feeding. It controlled harmful fermentation processes and stimulated short-chain fatty acid production to a greater extent in low than in high fiber diets, suggesting an improved fermentation of low fiber feed carbohydrates and eventually an increased availability of short-chain fatty acids for the host.

Acetates↗

PubMed1998

NMR detection of 13CH313COOH from 3-13C-glucose: a signature for Bifidobacterium fermentation in the intestinal tract.

The gastrointestinal tracts of breast-fed infants are colonized more easily with bifidobacteria than are those of formula-fed infants. Colonization is thought to reduce infant diarrhea. Amendments to formulas that improve colonization by bifidobacteria are being actively investigated. Colonization studies almost invariably require measurements of the concentration of the bifidobacteria in feces to assess their importance in the colon. We investigated the use of nuclear magnetic resonance (NMR) analysis of products of fermentations of 1- and 3-13C-glucose to evaluate the importance of bifidobacteria in the colonic ecosystem. Bifidobacteria use a unique pathway of hexose catabolism to produce primarily acetate and lactate. The fermentation yields 3 mol of acetate from 2 mol of glucose. Two of the acetates are formed from C1 and C2 of glucose and the third is formed entirely from C3 of glucose. We first employed high resolution NMR to verify the pathway used by a pure culture of Bifidobacterium bifidum. The major products of fermentation of 1- and 3-13C-glucose were acetate and lactate. Most of the 13C from 3-13C-glucose was in 13CH313COOH with equal enrichment in the methyl and carboxyl groups. The 13C-acetate from 1-13C-glucose was almost entirely enriched in the methyl of acetate and no 13CH313COOH was produced. NMR analysis of glucose fermentation by the colonic flora of a 158-d-old strictly breast-fed infant showed production of 13CH313COOH from 3-13C-glucose. The amount of 13CH313COOH formed established that the Bifidobacterium pathway was the major pathway used for glucose fermentation by this infant's colonic microbes.

Acetic Acid↗