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PubMed1981

Effect of monensin on the fermentation of basal rations in the Rumen Simulation Technique (Rusitec).

1. A long-term experiment was made with the Rumen Simulation Technique (Rusitec), in which the fermentation of a mixed ration of hay (10 g/d) and bruised barley (5 g/d) was compared with the fermentation of the same diet in the presence of 2, 10 and 50 mg monensin/d. 2. Monensin depressed the production of acetic and butyric acids, markedly increased the production of propionic acid and virtually, eliminated the production of isovaleric acid. The production of methane was decreased in the presence of monensin, but this decrease could be accounted for entirely by the changes in the production of volatile fatty acids and redistribution of metabolic hydrogen. 3. The digestibility of dry matter (DM) in the rations declined in the presence of monensin. Determinations of the rates of digestion showed that the digestion of the readily-fermented food in the initial stages was not affected by monensin, but that at 24 h digestion had been inhibited by monensin. The inhibition was due entirely to its effect on the digestion of the fibrous components. Digestion of non-fibrous material was not affected. 4. The efficiency of microbial growth, expressed as g dry weight/mol ATP formed (YATP) and in terms of DM digested, tended to be increased by monensin. This however occurred only at high, non-practical doses. 5. Urease (EC 3. 5. 1. 5) was induced by the addition of urea of the fermentation, but monensin had no effect on urease activity. Although monensin increased the activity of protease in washed suspensions, more food protein apparently escaped degradation. This may have been due to decreased deaminative activity. 6. Monensin altered the microscopic appearance of the fermentation fluid, and changed the activity of some enzymes in sonicated extracts, including alkaline phosphatase (EC 3. 1. 3. 1), acetate kinase (EC 2. 7. 2. 1) and succinate dehydrogenase (EC 1. 3. 99. 1). These results are discussed in terms of known sensitivities of rumen microbes to monensin and their contribution to the fermentation as a whole.

Animal Feed↗
PubMed1981

Effects of the antibiotic monensin and an inhibitor of methanogenesis on in vitro continuous rumen fermentations.

1. The effects of a methane inhibitor, ICI 111075, and a propionate enhancer, monensin, were studied using in vitro continuous fermenters. 2. Both compounds increased the yield of substrate energy, carbon and hydrogen in volatile fatty acids (VFA). This was mainly due to an increase in the molar proportion of propionic acid. 3. Improved yields of VFA were accompanied by reductions in methane production and microbial yield. 4. Since published information showed that monensin reduced rumen dilution rate in vivo an analogous in vitro system was proposed in which a high dilution rate control fermenter was compared with a monensin treated fermenter set to run at a low dilution rate. 5. Results showed that the general intrinsic microbial activity of the chemical manipulators was not affected by changes in dilution rate. Changing dilution rate in addition to chemical treatment however resulted in substantial modifications in the net effect on the fermentation. 6. The practical implications of reducing rumen dilution rate as a side effect of chemically manipulating the rumen fermentation could involve changes in food intake, increased importance of secondary fermentations and a reduced effect of nutrients not degraded in the rumen.

Animals↗
PubMed1994

Evaluation of fermentability of acid-treated maize husk by rat caecal bacteria in vivo and in vitro.

Fermentable energy in insoluble dietary fibre (DF) sources was evaluated by in vivo and in vitro methods using rats. Test diets contained 50 and 100 g maize husk or organic-acid-treated maize husk/kg diet. Soluble fractions were removed from both the DF sources by washing. The acid treatment increased digestibility by a microbial hemicellulase from 12.7% to 32.6%. The fermentability of DF was evaluated by measurement of the production rate of short-chain fatty acids (SCFA) in a short-term in vitro incubation of the caecal contents of rats fed on test diets for 22 d. The production rates of the major SCFA, acetic, propionic and butyric acids, were increased by feeding both DF sources, and these production rates in the acid-treated DF group were significantly higher than those in the untreated DF group. The production rate of a minor SCFA, isovaleric acid, was decreased by feeding both diets. The production rate of total SCFA in rats given the acid-treated maize husk was 32.6% higher than that in rats given the untreated maize husk. The fermentable energy in DF was estimated in vivo by subtracting the faecal excretion of DF energy from ingested DF energy. The fermentable energy in DF was increased by the acid treatment (32.5% in maize husk and 63.4% in acid-treated maize husk), which agreed with the SCFA production rate predicted in the caecum. These results indicate that a short-term incubation of caecal contents is a useful method for evaluation of the fermentability of DF sources, and that acid treatment can increase the fermentability of an insoluble DF source.

Acids↗
PubMed2005

The effect of enzyme treatment on the in vitro fermentation of lucerne incubated with equine faecal inocula.

A series of experiments was conducted to determine the effects of a fibrolytic enzyme preparation (enzyme 1; E1) on the in vitro fermentation of lucerne incubated with equine faecal inocula. In experiment 1, high-temperature-dried (HT) lucerne was treated with five levels of E1 (0 to 2.4 ml/g DM) and incubated at 50 degrees C for 20 h. Samples then received a simulated foregut digestion (SFD) treatment before DM and NSP analysis. In experiment 2, HT lucerne was treated with the same enzyme levels used in experiment 1. Samples were then split into two groups; plus or minus an SFD treatment before in vitro fermentation using an equine faecal inoculum. In experiment 3, fresh and wilted lucerne were treated with the same levels of E1 as experiments 1 and 2, incubated at 50 degrees C for 20 h, then fermented in vitro. For experiment 4, fresh and wilted lucerne were treated with low levels (0 to 0.008 ml/g DM) of E1 before fermentation. E1 significantly (P<0.05) enhanced DM and NSP losses from HT lucerne following SFD treatment compared with the control. High levels of E1 significantly (P<0.05) enhanced the rate, but not extent, of fermentation of HT, wilted and fresh lucerne; however, low levels of E1 were ineffective. At higher application levels, E1 appears to have considerable potential to enhance the nutritive value of lucerne for horses. Information on the fermentation kinetics of the substrates was valuable; all end-point measurements showed no effect of enzyme treatment.

Animal Feed↗
PubMed1997

Antiproliferative effect of fermented milk on the growth of a human breast cancer cell line.

In vivo and in vitro studies have shown an antitumor activity of Lactobacilli in colon cancer, and some epidemiologic studies have indicated a reduced risk of breast cancer in women who consume fermented milk products. We studied the direct effect of milk fermented by five bacteria strains (Bifidobacterium infantis, Bifidobacterium bifidum, Bifidobacterium animalis, Lactobacillus acidophilus, and Lactobacillus paracasei) on the growth of the MCF7 breast cancer cell line. Our results showed a growth inhibition induced by all fermented milks, even though B. infantis and L. acidophilus were the most effective (85% inhibition after 9 days). The antiproliferative effect was not related to the presence of bacteria in fermented milk, and neither whole milk (crude or ultrahigh temperature sterlizied) nor its main fractions (lactalbumin or beta-lactoglobulin fraction) affected cell growth. Our findings suggest the presence of an ex novo soluble compound produced by lactic acid bacteria during milk fermentation or the microbial transformation of some milk components in a biologically active form. Although the mechanism of the antitumor activity is not clear, the present study suggests the potentiality offered by fermented milk as producers of compounds with antiproliferative activity useful in the prevention and therapy of solid tumors like breast cancer.

Animals↗
PubMed2004

Key influential factors for sludge pre-fermentation process design--a case study.

Sewage sludge pre-fermentation process produces readily biodegradable carbon, which is essential for reliable biological phosphorus removal and efficient denitrification. This bench scale study was to develop site-specific design parameters for a sludge fermentation process, and to look into the effects of various influential factors. The key factors investigated induded solids retention time (4-8 days), temperature (9-19 degrees C) and sludge concentrations (0.5%-4% DS). The optimum Volatile Fatty Adds yield was found at a sludge concentration of 1%-1.5% DS. A solid retention time of 4 days at 15-20 degrees C was found to be most cost effective. The fermentation reaction was temperature sensitive, which was found to be inefficient at temperature below 12-15 degrees C. Under the optimum conditions, 80-100 mgVFA g(-1) VSS can be generated from fermentation process, which will result in an increase of 20-24 mg l(-1) in the settled sewage based on average flow. A significant pathogen reduction level was also demonstrated over the fermentation period. Liquid sludge from the small rural wastewater treatment plants is often imported to a regional sludge treatment centre for more advanced treatment to comply with the Regulations. The suitability of this imported sludge for pre-fermentation process was also investigated in this study.

Biodegradation, Environmental↗
PubMed2005

The effect of fermentation and storage on free amino acids of tarhana.

A study on the evaluation of free amino acids (FAAs) in tarhana during fermentation and storage was performed. The FAAs in tarhana were determined by RP-HPLC with a fluorescence detector following extraction from the sample and derivatization with dansyl chloride. The amount of FAAs increased significantly (p<0.01) during fermentation and storage. The increase in the content of total free amino acids (TFAAs) and total free essential amino acids (TFEAAs) of fermented tarhana, which was used with yogurt bacteria and baker's yeast, was 57% and 93%, respectively. The amino acids primarily responsible for the increase were valine and tryptophan followed by methionine, alanine, isoleucine + leucine, phenylalanine, arginine, proline, and lysine. The TFAA content of tarhana at the end of fermentation was found to be 8% of total protein (16.8%). The ratio of TFEAAs/TFAAs was initially 0.46 and increased to 0.57 at the end of fermentation. The TFAA content of wet tarhanas was higher than that of the dry counterpart. It was found that the TFAA content of dry tarhana was 25% lower than the fresh wet tarhana (FWT), at the end of fermentation. It was concluded that the decrease in FAAs in dry tarhana was due to the Maillard reaction and partial degradation of FAAs during dehydration.

Amino Acids↗
PubMed1991

Cellulose fermentation capacity of the hindgut and nitrogen turnover in the hindgut of sows as evaluated by oral and intracecal supply of purified cellulose.

Adult sows fed a constant amount of a basal diet received purified cellulose either orally at levels of 0 and 475 g/animal.d (Experiment 1) or intracecally at levels of 0, 285, 570 and 855 g/animal.d (Experiment 2). Each experiment consisted of subsequent periods of faeces and urine collection with the animals re-allocated to the treatments each time. With that, a total of 36 observations on each parameter was achieved. The faecal samples were analyzed for the contents of organic matter, cell wall carbohydrates and various nitrogen fractions such as bacterial N and undigested dietary N. Furthermore, N balance, urinary allantoin excretion and plasma urea concentrations were determined. In a preliminary study, the effects of freeze-drying and of shaking of the faecal samples as suspensions with water (in order to release bacteria from fibre) on content and composition of faecal nitrogen had turned out to be reproducible. Cellulose significantly enhanced faecal nitrogen loss whereas N retention was not affected due to the counteraction of urinary N loss. Plasma urea concentration reflected the situation with urinary N. The proportion of undigested dietary N and of water-soluble protein in total faecal N was somewhat increased by cellulose at cost of the bacterial N proportion which accounted for about 72% of total N on average. Urinary allantoin did not respond to the higher bacterial activity in the hindgut in the presence of supplementary cellulose. Cellulose significantly decreased the apparent N digestibility by on average about 3 percentage units per 100 g of supplementary cellulose. True N digestibility was also reduced by cellulose but did not go below 95%. The supplementary cellulose was fermented in the hindgut at similar rates of on average about 60% regardless of the route of administration. The almost 100 g of native cellulose incorporated in the basal diets were lignified by about 20%, and that is why they were fermented at a rate of only about 30%. The rate of fermentation was only slightly decreasing with increasing amounts of supplementary cellulose, and a daily quantity of 564 g (11 g/W0.75) cellulose was fermented on average if the highest level of cellulose was provided. This was within a range exclusively reported for easily-fermentable carbohydrates but was achieved in the case of cellulose only at a consistently higher level of supply. The true efficiency of bacterial protein synthesis was 5.2 g bacterial protein/100 g supplementary cellulose on average. The apparent efficiency was 60% higher averaging 8.4 g bacterial protein/100 g further apparently fermented organic matter.

Animals↗
PubMed2005

Symbiotic fermentation, digesta passage, and gastrointestinal morphology in bullfrog tadpoles (Rana catesbeiana).

Relative to other herbivorous vertebrates, the nutritional ecology and digestive physiology of anuran larvae remain poorly understood. Our objective was to compare gut structure and inhabitants, digesta passage, and microbial fermentation in bullfrog tadpoles (Rana catesbeiana) to those in other herbivores. Bullfrog tadpole gastrointestinal tracts were long and voluminous, with an enlarged colon that harbored a diverse symbiotic community. The transit time for particulate markers passing through bullfrog tadpoles was 6 h, the median retention time was 8-10 h, and gut clearance was 10-14 h postingestion. Relatively high levels of short-chain fatty acids in the hindgut of tadpoles indicated active microbial fermentation in this gut region. This report represents the first account of gastrointestinal fermentation in the class Amphibia. On the basis of in vitro fermentation assays, we estimated that microbial fermentation in the hindgut provides 20% of the total daily energy requirement of bullfrog tadpoles. These tadpoles also exhibited coprophagy, a practice that provides important nutritive gains in other herbivores. The physiological and behavioral characteristics of these tadpoles are remarkably similar to those of other small-bodied, hindgut-fermenting vertebrates, suggesting convergent digestive strategies among a broad range of herbivorous taxa.

Animals↗
PubMed1989

Prophylactic and therapeutic aspects of fermented milk.

Many claims have been made concerning prophylactic and therapeutic effects of fermented bovine milk consumption. Of these, the amelioration of lactose intolerance symptoms in humans and rats due to the reduced lactose level caused by fermentation is convincingly documented and corroborated. In addition, some kinds of fermentation microbes can contribute to lactose digestion in vivo thus augmenting the preingestive fermentative decrease of lactose. Relief of the growth inhibition and the gastrointestinal infection susceptibility due to high dietary lactose levels can also be achieved by fermentation of milk lactose. The hypocholesterolemic activity of fermented milk is apparently related to a similar uncharacterized activity of ordinary milk. Antitumorigenic effects in rats have been reported. Microfloral alterations due to dietary dairy microbes have been reported to retard the development of colon cancer. Purported human longevity effects have not been supported by appropriate data.

Animals↗
PubMed1997

Bacterial fermentation of fructooligosaccharides and resistant starch in patients with an ileal pouch-anal anastomosis.

Patients with large bowel disease may undergo ileal pouch-anal anastomosis, in which the colon is removed and part of the distal ileum is used to construct a pelvic reservoir. Competence of the ileal pouch to ferment carbohydrates is associated with the absence of pouchitis. However, the extent to which bacterial fermentation takes place and whether it is affected by diet are unclear. We investigated fermentation of two nondigestible carbohydrates, fructooligosaccharides and resistant starch, in 15 healthy patients with an ileal pouch by using a placebo-controlled crossover design (with glucose as the placebo). Apparent fermentability of fructooligosaccharides was 83%; that of resistant starch was 46%. Resistant starch increased fecal excretion of butyrate by 69% whereas fructooligosaccharides reduced excretion of amino acid-derived isobutyrate by 94% and of isovalerate by 77%. Fructooligosaccharides also significantly increased fecal weight (651 compared with 541 g/d) and breath-hydrogen excretion (286 compared with 85 ppm x h). Bacterial fermentation of nondigestible carbohydrates in pouches takes place to an appreciable extent and in a substrate-specific manner. The relation between such fermentation and inflammation of the pouch (pouchitis) deserves study.

Adult↗
PubMed1998

Energy balance and thermogenesis in rats consuming nonstarch polysaccharides of various fermentabilities.

BACKGROUND: The equivalents of dietary protein, fat, and available carbohydrate as fuels for maintenance (kJ apparent metabolizable energy/kJ maintenance requirement) are known from classical experiments and are similar across species; that for nonstarch polysaccharide (NSP) is undetermined. OBJECTIVES: Our objectives were to determine the energy equivalent of NSP and the thermic responses to NSP. DESIGN: In a randomized block design, 120 rats were treated in groups of 10 for 28 d with a basal diet (control) supplemented with starch and 10 different NSP treatments in amounts between 38 and 92 g/kg basal diet. Cellulose and starch were references. Thermic responses, deduced from body-composition changes and modeling of energy disposition, and energy and substrate excretion were determined. RESULTS: NSP had fermentabilities between 0.01 and 0.93 g/g intake. Fermentability, partial digestible energy, and net metabolizable energy values of NSP were closely related. Generally, 51% of apparent metabolizable energy from NSP (fermentable gross energy) met maintenance requirements. Diet (energy)-induced thermogenesis (DIT) was evident from whole diets. Fermentable NSP supplied net metabolizable energy and caused DIT. After DIT and fermentation were accounted for, NSP-induced thermogenesis was generally -2+/-4% (x+/-SEM) of gross NSP energy, except for an outlying pectic preparation, which was 33% (P< 0.1). CONCLUSIONS: The energy equivalent of NSP was 196 (100/51) kJ/kJ, compared with 128, 105, and 100 for protein, fat, and glucose, respectively, from the classical experiments. With the exception of pectic NSP, NSP does not induce thermogenesis in excess of that associated with DIT and fermentation.

Animals↗
PubMed2000

Consumption of fermented and nonfermented dairy products: effects on cholesterol concentrations and metabolism.

The objective of this article was to review existing literature concerning the effects and mechanisms of action of fermented dairy products on serum cholesterol concentrations. Although not without exception, existing evidence from animal and human studies suggests a moderate cholesterol-lowering action of fermented dairy products. Mechanistically, fermented milk has been shown to cause an increase in human gut bacterial content. These bacteria, once resident in the large intestine, are believed to ferment food-derived indigestible carbohydrates. Such fermentation causes increased production of short-chain fatty acids, which decreases circulatory cholesterol concentrations either by inhibiting hepatic cholesterol synthesis or by redistributing cholesterol from plasma to the liver. Furthermore, increased bacterial activity in the large intestine results in enhanced bile acid deconjugation. Deconjugated bile acids are not well absorbed by the gut mucosa and are excreted. Consequently, cholesterol, being a precursor of bile acids, is utilized to a greater extent for de novo bile acid synthesis. These actions combined are proposed as contributing mechanisms to the association of fermented milk consumption with decreased circulating cholesterol concentrations.

Animals↗
PubMed2001

Inconsistency between glycemic and insulinemic responses to regular and fermented milk products.

BACKGROUND: Foods with a low glycemic index are increasingly being acknowledged as beneficial in relation to the insulin resistance syndrome. Certain organic acids can lower the glycemic index of bread products. However, the possible effect of acids in fermented milk products on the glycemic index and on insulinemic characteristics has not been addressed. The metabolic effects of fermented milk or pickled products used as additives to mixed meals have also not been addressed. OBJECTIVES: One objective was to characterize the glycemic and insulinemic responses after intake of regular or fermented milk products (study 1). In addition, the acute metabolic effect of fermented milk (yogurt) and pickled cucumber as supplements to a traditional breakfast based on a high-glycemic index bread was evaluated (study 2). DESIGN: Ten healthy volunteers were served different breakfast meals after an overnight fast. Capillary blood samples were collected before and during 2 (study 1) or 3 (study 2) h after the meal. White-wheat bread was used as a reference meal in both studies. RESULTS: The lactic acid in the fermented milk products did not lower the glycemic and insulinemic indexes. Despite low glycemic indexes of 15-30, all of the milk products produced high insulinemic indexes of 90-98, which were not significantly different from the insulinemic index of the reference bread. Addition of fermented milk (yogurt) and pickled cucumber to a breakfast with a high-glycemic index bread significantly lowered postprandial glycemia and insulinemia compared with the reference meal. In contrast, addition of regular milk and fresh cucumber had no favorable effect on the metabolic responses. CONCLUSIONS: Milk products appear insulinotropic as judged from 3-fold to 6-fold higher insulinemic indexes than expected from the corresponding glycemic indexes. The presence of organic acids may counteract the insulinotropic effect of milk in mixed meals.

Adult↗
PubMed2006

Colonic fermentation of indigestible carbohydrates contributes to the second-meal effect.

BACKGROUND: Low postprandial blood glucose is associated with low risk of metabolic diseases. A meal's ability to diminish the glucose response to carbohydrates eaten during the following meal is known as the "second-meal effect" (SME). The reduced glycemia elicited by low-glycemic-index (LGI) foods consumed during the first meal has been suggested as the main mechanism for SME. However, LGI foods often increase colonic fermentation because of the presence of fiber and resistant starch. OBJECTIVE: The objective was to study the SME of greater fermentation of high-glycemic-index (HGI) and LGI carbohydrates eaten during a previous meal. DESIGN: Ten healthy volunteers ate 3 breakfast test meals consisting of sponge cakes made with rapidly digestible, nonfermentable amylopectin starch plus cellulose (HGI meal), amylopectin starch plus the fermentable disaccharide lactulose (HGI-Lac meal), or slowly digestible, partly fermentable amylose starch plus cellulose (LGI meal). Five hours later, subjects were fed the same standard lunch containing 93 g available carbohydrates. Blood was collected for measurement of glucose, insulin, and nonesterified fatty acids (NEFAs). Breath hydrogen was measured as a marker of colonic fermentation. Postlunch gastric emptying was measured by using ultrasonography. RESULTS: Both the HGI-Lac and LGI meals improved glucose tolerance at lunch. In the case of the HGI-Lac meal, this effect was concomitant with low NEFA concentrations and delayed gastric emptying. CONCLUSION: Fermentable carbohydrates, independent of their effect on a food's glycemic index, have the potential to regulate postprandial responses to a second meal by reducing NEFA competition for glucose disposal and, to a minor extent, by affecting intestinal motility.

Adult↗
PubMed1995

The consequences of fruit and vegetable fibre fermentation on their binding capacity for MeIQx and the effects of soluble fibre sources on the binding affinity of wheat bran preparations.

Fruits and vegetables provide dietary fibre some of which is partly soluble in the upper gut; in the colon it is highly fermentable. Using alcohol-insoluble residues prepared from a range of fruits and vegetables the effects of fermentation on the changes in composition and binding capacity have been assessed for the hydrophobic mutagen 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). Fermentation was extensive and resulted in destruction of most of the pectic polysaccharides. Of the unfermented vegetable fibre only cabbage had a measurable hydrophobic binding capacity. The binding capacities of unfermented apple, carrot and sugar beet were negligible. After fermentation, binding capacities, (per mg of fermented residue), increased. Although fermented cabbage was found to have the highest capacity of the fruit and vegetable fibres this remained less than the least effective of unfermented wheat bran samples which had a relatively high affinity for MeIQx. Mucin inhibited the binding of MeIQx to wheat bran fibre but apple fibre did not. The results show that the contribution of fruit and vegetable fibre to a hydrophobic binding matrix in the colon is insignificant and the suggested harmful effect of fruit and vegetable fibre, maintaining hydrophobic mutagens in solution, can be prevented by the presence of wheat bran fibre.

Carcinogens↗
PubMed1991

Fermentable carbohydrate reaching the colon after ingestion of oats in humans.

A simulated digestion technique was used to investigate the characteristics of starch hydrolysis in uncooked, cooked and extrusion-cooked oat products in vitro. The rate and extent of starch hydrolysis were both significantly lower in uncooked rolled oats than in the same material after brief boiling or extrusion cooking. A similar degree of maldigestion in vivo would lead to as much as an estimated 68% of oat starch entering the colon. Breath-hydrogen measurements were used to compare the fermentable carbohydrate content of uncooked and briefly boiled rolled oats in human volunteers and to estimate the relative contributions of soluble dietary fiber and undigested starch to the fermented component. Isolated oat gum (beta-glucan) was readily fermented in vivo and was apparently the main fermentable component of cooked rolled oats. Uncooked rolled oats gave a higher excess hydrogen production than cooked oats, but the results were variable and the differences not statistically significant. In an additional experiment, lactulose was used as a fermentable reference material to calculate the apparent fermentable carbohydrate content of rolled oats and oat gum. Uncooked rolled oats were estimated to contain a statistically significant quantity of undigested starch, amounting at most to 1.01 +/- 0.40 g (mean +/- SEM) of undigested starch per 50 g of fresh weight. We concluded that starch hydrolysis in oats is limited to some extent by the physical state of the food matrix, but this effect may be greatly overestimated by simulated digestion procedures in vitro.

Adult↗
PubMed1997

In vitro lactose fermentation by human colonic bacteria is modified by Lactobacillus acidophilus supplementation.

Adaptation of the colonic flora to lactose may contribute to lactose digestion in lactose maldigesters, and supplementation with Lactobacillus acidophilus may modify colonic fermentation of lactose and short-chain fatty acid production. We evaluated the capability of colonic bacteria to ferment lactose and the ability of L. acidophilus to modify lactose fermentation by the colonic microflora in vitro. An anaerobic continuous culture was established and inoculated with fresh samples of human feces. Lactose infusion was maintained at 25 g/d and pH at 6.7. L. acidophilus strain LA-1 (1.5 x 10(10) cells) was introduced into the fermenter on d 0 or added daily on d 0 through 4. The control was the continuous culture without the addition of lactobacilli. Rapid adaptation of colonic bacteria to lactose occurred within 1-2 d, with a significant decrease in lactose concentration and increase in beta-galactosidase activity, and lactose concentrations fell below 3 mmol/L by d 7. Supplementation with strain LA-1 resulted in a significantly greater decrease in lactose concentration and greater increase in acetate and propionate production within the first day compared with the control group. However, there was no significant difference between the fermentation treated with L. acidophilus daily and the control after the first day. These data suggest that the colonic bacteria adapt quickly to lactose, causing efficient utilization of lactose. L. acidophilus supplementation may enhance lactose fermentation during early periods when the adaptation is not established in this model.

Adult↗