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Rapid identification of Lactobacillus acidophilus by restriction analysis of the 16S-23S rRNA intergenic spacer region and flanking 23S rRNA gene.

A rapid molecular approach was developed for the initial identification of Lactobacillus acidophilus strains which are difficult to identify using a single biochemical test. The 16S-23S rRNA intergenic spacer regions and flanking 23S rRNA genes of 19 strains of lactobacilli were amplified and the nucleotide sequences and restriction site polymorphisms were analyzed. AluI was the most useful of the restriction enzymes analyzed and produced reproducible digestion profiles in the L. helveticus, L. plantarum, and L. casei groups, as well as in L. acidophilus. This restriction fragment length polymorphism method may be useful for the identification of L. acidophilus strains in dairy products.

3' Flanking Region↗

Identification and inactivation of genetic loci involved with Lactobacillus acidophilus acid tolerance.

Amino acid decarboxylation-antiporter reactions are one of the most important systems for maintaining intracellular pH between physiological limits under acid stress. We analyzed the Lactobacillus acidophilus NCFM complete genome sequence and selected four open reading frames with similarities to genes involved with decarboxylation reactions involved in acid tolerance in several microorganisms. Putative genes encoding an ornithine decarboxylase, an amino acid permease, a glutamate gamma-aminobutyrate antiporter, and a transcriptional regulator were disrupted by insertional inactivation. The ability of L. acidophilus to survive low-pH conditions, such as those encountered in the stomach or fermented dairy foods, was investigated and compared to the abilities of early- and late-stationary-phase cells of the mutants by challenging them with a variety of acidic conditions. All of the integrants were more sensitive to low pH than the parental strain. Interestingly, each integrant also exhibited an adaptive acid response during logarithmic growth, indicating that multiple mechanisms are present and orchestrated in L. acidophilus in response to acid challenge.

Base Sequence↗

Effect of Lactobacillus acidophilus supplementation of milk replacer on preweaning performance of calves.

Forty Holstein-Friesian calves were used to evaluate the effect on young calves of daily dietary supplementation with Lactobacillus acidophilus. Calves were randomly assigned at 2 d of age to one of two treatments; 1) milk replacer with no additives or 2) milk replacer supplemented with 1 ml (5 x 10(7)) of viable L. acidophilus bacteria at each of two feedings per day. Milk replacer was reconstituted to 12% DM and fed at 10% of BW/d for the duration of the 6-wk trial. A commercial starter pellet was offered for ad libitum intake from 7 d of age. Treatment had no effect on actual BW at any stage or on total BW gain; however, average daily gain during wk 2 was affected by L. acidophilus supplementation. Calves receiving L. acidophilus maintained initial BW, and the control calves lost BW until 2 wk of age, at an average rate of 112 g/d. Starter intake, total DMI, feed efficiency, and occurrence of diarrhea were unaffected by treatment. Therefore, L. acidophilus supplementation for calves fed milk replacer may be beneficial during the first 2 wk of life.

Animal Feed↗

Poultry offal ensiled with lactobacillus acidophilus for growing and finishing swine diets.

Poultry offal (heads, feet, viscera) from a broiler processing plant was ground and mixed with corn, dried molasses and a Lactobacillus acidophilus culture. Fermentation was shown to be effective in batch sizes of 3.8, 75.7 and 208.1 liters, as well as a 1,360-kg silo. It was generally complete at 72 h. In trial 1, rats were fed silage mixtures of 60:30:5:5, 45:45:5:5 and 30:60:5:5, offal, corn, molasses and inoculant, respectively. Rats did not gain as well when fed the silage diets (P less than .05) as when fed the basal diet; however, the ranking of silages was 45:45, 60:30 and 30:60, offal-to-corn ratio for rat daily gains and feed conversions. In trial 2, growing-finishing pigs were fed the 60:30:5:5 silage at rates of 0, 10, 20 and 30% of the diet. Average daily gains and feed-to-gain ratios were not affected by including offal silage at up to 20% of the diet, but 30% offal silage in diets resulted in depressed gains (P less than .05) and increased feed-to-gain ratios. Carcasses were not different among treatments for dressing percentage, length, average backfat and percentage of ham, loin, shoulder, lean cuts and primal cuts. Carcasses from pigs fed 20 and 30% offal silage had significantly darker and firmer loin-eyes than those from control fed pigs. Marbling was higher (P less than .05) in loin-eyes from pigs fed 30% offal silage as compared with those from pigs fed 0% offal silage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

Conjugated linoleic acid accumulation via 10-hydroxy-12-octadecaenoic acid during microaerobic transformation of linoleic acid by Lactobacillus acidophilus.

Specific isomers of conjugated linoleic acid (CLA), a fatty acid with potentially beneficial physiological and anticarcinogenic effects, were efficiently produced from linoleic acid by washed cells of Lactobacillus acidophilus AKU 1137 under microaerobic conditions, and the metabolic pathway of CLA production from linoleic acid is explained for the first time. The CLA isomers produced were identified as cis-9, trans-11- or trans-9, cis-11-octadecadienoic acid and trans-9, trans-11-octadecadienoic acid. Preceding the production of CLA, hydroxy fatty acids identified as 10-hydroxy-cis-12-octadecaenoic acid and 10-hydroxy-trans-12-octadecaenoic acid had accumulated. The isolated 10-hydroxy-cis-12-octadecaenoic acid was transformed into CLA during incubation with washed cells of L. acidophilus, suggesting that this hydroxy fatty acid is one of the intermediates of CLA production from linoleic acid. The washed cells of L. acidophilus producing high levels of CLA were obtained by cultivation in a medium containing linoleic acid, indicating that the enzyme system for CLA production is induced by linoleic acid. After 4 days of reaction with these washed cells, more than 95% of the added linoleic acid (5 mg/ml) was transformed into CLA, and the CLA content in total fatty acids recovered exceeded 80% (wt/wt). Almost all of the CLA produced was in the cells or was associated with the cells as free fatty acid.

Aerobiosis↗

Effect of chronic ingestion of a fermented dairy product containing Lactobacillus acidophilus and Bifidobacterium bifidum on metabolic activities of the colonic flora in humans.

Nine healthy volunteers were studied before, during, and after ingesting a fermented dairy product containing Lactobacillus acidophilus, Bifidobacterium bifidum, and mesophilic cultures (Streptococcus lactis and S cremoris) for 3 wk. Hydrogen and methane productions and fecal beta-galactosidase and beta-glucosidase activities were measured as indicators of fermentation capacity of the colonic flora. Fecal concentrations of nitroreductase, azoreductase, and beta-glucuronidase, which may be implicated in colonic carcinogenesis, were also assessed. Hydrogen and methane productions, fecal beta-galactosidase, beta-glucuronidase, and azoreductase activities did not change over three 3-wk periods whereas fecal beta-glucosidase activity increased (42 +/- 6, 91 +/- 12, and 40 +/- 6 IU/g N, P less than 0.01) and nitroreductase decreased (0.87 +/- 0.13, 0.54 +/- 0.11, and 0.57 +/- 0.08 IU/g N, P less than 0.05).

Adult↗

Survival of Lactobacillus acidophilus LA-5 and Bifidobacterium bifidum BB-02 in white-brined cheese.

The viability of probiotic cultures used as adjunct cultures including Bifidobacterium bifidum BB-02 and Lactobacillus acidophilus LA-5 in white-brined cheese was investigated. The microbiological and biochemical properties of cheeses were assessed throughout 90 days of storage. Two inoculum rates for probiotic starters (2.5% and 5.0%, v/v, corresponding to (1.0-1.3)x10(9) cfu/g and (2.0-2.1)x10(9) cfu/g, respectively) were compared with the control cheese. Results obtained showed that a higher inoculum rate resulted in faster proteolysis. The cheese inoculated with 5% probiotic strains had higher water-soluble nitrogen, non-protein nitrogen, proteose-peptone nitrogen and tyrosine values than the other experimental cheeses. At the end of storage, the cheese supplemented with 5% probiotic culture had a ripening coefficient of 28.3%, followed by 2.5% probiotic strains containing the sample being 24.9%, and the control being 23.6%, respectively. It was also found that the colony counts of both probiotic microorganisms declined during storage. After 90 days of storage, the number of probiotic colonies were still around the threshold for a minimum probiotic effect (10(6) cfu/g).

Bifidobacterium↗

The effect of Lactobacillus acidophilus on the production and chemical composition of hen's eggs.

Laying hens were fed for a 48-wk period with a basal diet supplemented with a selected strain of Lactobacillus acidophilus at levels up to four million viable cells per gram of feed. Levels of egg production and feed conversion were significantly higher (8 and 14.8%, respectively) than in the control flock, and cholesterol values in yolks were decreased by 18.8%. It is suggested that the latter effect was a reflection of lower serum cholesterol concentrations in treated birds; a maximum reduction of over 55% followed incorporation of the culture into the feed. The level of viable cells in the feed was confirmed as being critical to register the above effects.

Animal Feed↗

Heat-killed Lactobacillus acidophilus inhibits adhesion of Escherichia coli B41 to HeLa cells.

Escherichia coli B41 (O101: K99: F41: ST+) adheres to HeLa 229 cells in a diffuse pattern. Heat-killed (100-105 degrees C) Lactobacillus acidophilus (Lactéol strain) was found to inhibit this adhesion in a dose-dependent manner. This inhibitory action was lost after lysis of the L acidophilus, suggesting steric hindrance of E coli adhesion sites rather than competition for a common binding site. A thermostable factor (100-105 degrees C) excreted by L acidophilus into the medium may be required for the adhesion of L acidophilus to HeLa cells, and for the inhibition of adhesion of E coli to these cells.

Bacterial Adhesion↗

Adhesion of human Lactobacillus acidophilus strain LB to human enterocyte-like Caco-2 cells.

Twenty-five strains of lactobacilli were tested for their ability to adhere to human enterocyte-like Caco-2 cells in culture. Seven Lactobacillus strains adhered well to the Caco-2 cells, of which three possessed calcium-independent adhesion properties. A high level of calcium-independent adhesion was observed with the human stool isolate Lactobacillus acidophilus strain LB. Scanning electron microscopy revealed that this strain adhered to the apical brush border of the cells. Adhesion increased in parallel with the morphological and functional differentiation of the Caco-2 cells. Two Lactobacillus components were involved in this adhesion. One was protease-resistant and bacterial-surface-associated; the other was heat-stable, extracellular and protease-sensitive.

Bacterial Adhesion↗

The growth of Gardnerella vaginalis and Lactobacillus acidophilus in Sorbarod biofilms.

Sorbarod biofilms were investigated for their suitability in establishing continuous culture biofilms for the study of bacterial vaginosis. Two important organisms in the condition, Gardnerella vaginalis and Lactobacillus acidophilus, were studied. In contrast to growth in broth culture, both organisms were maintained for at least 96 h in a steady state on the biofilms. With G. vaginalis, the haemolytic activity was consistently maintained in the biofilms in contrast to short-term activity in broth culture which matched the bacterial titre. The simple Sorbarod system appears to be suitable for studying the growth conditions of bacteria in continuous culture and has potential for investigating interactions between micro-organisms.

Biofilms↗

Manufacturing of fermented goat milk with a mixed starter culture of Bifidobacterium animalis and Lactobacillus acidophilus in a controlled bioreactor.

AIMS: This work was undertaken to study the feasibility and the characteristics of a fermented product made of goat milk, using a mixed starter culture of Bifidobacterium animalis and Lactobacillus acidophilus under controlled conditions, and to determine their survival in the fermented milk during refrigerated storage. METHODS AND RESULTS: Goat milk was inoculated with Lact. acidophilus and Bif. animalis mixed starter, fermented in a glass bioreactor with controlled temperature (37 degrees C) and anaerobiosis, and monitored for growth and acidification. The fermented milk was then stored for 10 days under refrigeration, and monitored daily for starter microflora survival and pH changes. Lact. acidophilus viable counts reached a maximum of 7.1 x 10(8) colony-forming units (CFU) ml(-1), and Bif. animalis a maximum of 6.3 x 10(7) CFU ml(-1) by 20 h of fermentation. During refrigerated storage, both strains exhibited a good survival, with viable numbers remaining essentially constant throughout the experiment, whereas the pH of the fermented milk dropped slightly. CONCLUSIONS: Mixed cultures of Bif. animalis and Lact. acidophilus may be used to produce fermented goat milk with high counts of both probiotic strains. SIGNIFICANCE AND IMPACT OF THE STUDY: Goat milk fermented with Bif. animalis and Lact. acidophilus can be manufactured as an alternative probiotic dairy product.

Animals↗

Fructooligosaccharides and Lactobacillus acidophilus modify gut microbial populations, total tract nutrient digestibilities and fecal protein catabolite concentrations in healthy adult dogs.

The objective of this research was to determine whether fructooligosaccharides (FOS) and (or) Lactobacillus acidophilus (LAC) affected concentrations of gut microbial populations, fermentative end products and nutrient digestibilities in healthy adult dogs. Two experiments were performed using 40 adult dogs (20 dogs/experiment). Dogs in each experiment were randomly assigned to one of 4 treatments. Twice daily, treatments were given orally via gelatin capsules: 1) 2 g sucrose + 80 mg cellulose; 2) 2 g FOS + 80 mg cellulose; 3) 2 g sucrose + 1 x 10(9) colony forming units (cfu) LAC; or 4) 2 g FOS + 1 x 10(9) cfu LAC. Data were analyzed by the General Linear Models procedure of SAS. In Experiment 1, FOS resulted in lower (P = 0.08) Clostridium perfringens and greater fecal butyrate (P = 0.06) and lactate (P < 0.05) concentrations. In Experiment 2, FOS supplementation increased (P < 0.05) bifidobacteria, increased lactobacilli (P = 0.08), increased fecal lactate (P = 0.06) and butyrate (P < 0.05), and decreased (P < 0.05) fecal ammonia, isobutyrate, isovalerate and total branched-chain fatty acid concentrations. Dogs fed LAC had the highest fecal concentrations of hydrogen sulfide and methanethiol in Experiment 1 and dimethyl sulfide in Experiment 2, whereas dogs fed FOS had the lowest concentrations of these compounds. Overall, FOS appeared to enhance indices of gut health by positively altering gut microbial ecology and fecal protein catabolites, whereas LAC was more effective when fed in combination with FOS rather than fed alone.

Animals↗

Growth enhancement of Bifidobacterium lactis Bo and Lactobacillus acidophilus Ki by milk hydrolyzates.

The determination of the best conditions of preparation of a (tentatively) probiotic starter culture that might be suitable for cheese making composed solely of Bifidobacterium lactis Bo and Lactobacillus acidophilus Ki is critical if a consistently reliable acid production is to be achieved, especially because bifidobacteria have stringent requirements for growth. Therefore, we determined whether B. lactis Bo and L. acidophilus Ki required or benefitted from the addition of milk hydrolyzates (brought about by proteinase or neutrase as the nitrogen source). The growth and acid production of B. lactis in milk were affected by the addition of proteinase-mediated hydrolyzate and, to a lesser extent, by neutrase-mediated hydrolyzate; a higher degree of hydrolysis of either hydrolyzate resulted in greater biomass increase and greater acid production. This result suggests that the poor growth of bifidobacteria in milk is due partially to the lack of small peptides and free amino acids. The rates of growth and acidification by B. lactis were enhanced when cocultured with L. acidophilus (1:1 inoculum ratio). Conversely, the growth rates and acid production of L. acidophilus were not positively affected by the addition of either milk hydrolyzate. Although L. acidophilus grew slowly, its proteolytic system was apparently able to generate its own nitrogen source. Nevertheless, coculture with B. lactis (1:1 inoculum ratio) led to enhanced rates of growth and acidification when compared with that of the single strain, suggesting some degree of symbiosis between the strains.

Animals↗

Effect of milk fermented with Lactobacillus acidophilus strain L-92 on symptoms of Japanese cedar pollen allergy: a randomized placebo-controlled trial.

A placebo-controlled, single-blind study was conducted to evaluate the effects of Lactobacillus acidophilus strain L-92 (L-92) on the symptoms of Japanese cedar-pollen allergy. This study was carried out during the 2002 and 2003 seasons of Japanese cedar pollination. Twenty-three in-house volunteers were asked to drink 100 ml of heat-treated milk fermented with L-92 containing 5 x 10(10) of the bacteria, twice a day, for 6 consecutive weeks. A similar study was carried out during the 2003 season for 10 weeks, but the daily dose of bacteria was 2 x 10(10). A significant improvement of the ocular symptom-medication score (SMS) was observed in 2002 and of the score of distress of life in 2003. These data show that a daily oral intake of not less than 2 x 10(10) heat-treated L-92 cells improved the symptoms of Japanese cedar pollinosis, thereby contributing to reduce the dose of concomitant medications. However, no blood parameter was significantly affected in these trials.

Adult↗

Growth and lactic acid production by vaginal Lactobacillus acidophilus CRL 1259, and inhibition of uropathogenic Escherichia coli.

Lactic acid-producing lactobacilli were selected from 134 human vaginal isolates by testing their capability to inhibit the growth of different pathogenic micro-organisms. Lactobacillus acidophilus CRL 1259 (from the CERELA Culture Collection) was selected to study the effects of temperature, pH and culture medium on growth and lactic acid production. Growth parameters were estimated by using the model of Gompertz. Kinetics of inhibition of uropathogenic Escherichia coli were evaluated in mixed cultures of the pathogen and L. acidophilus. Optimal conditions for growth and lactic acid production by L. acidophilus were pH 6.5 or 8.0 and 37 degrees C. Under these conditions, growth was higher in LAPTg (yeast extract/peptone/tryptone/Tween 80/glucose) broth than in MRS (De Man-Rogosa-Sharpe) broth. However, lactic acid production was more efficient in MRS broth. Under optimal conditions for lactic acid production, L. acidophilus inhibited the growth of E. coli. These results suggest that inclusion of L. acidophilus CRL 1259 in probiotic products for vaginal application would be beneficial.

Adult↗