Effect of probiotic inocula on the population density of lactic acid bacteria and enteric pathogens in the intestine of weaning piglets

Because antibiotic resistance occurs in bacteria at an alarming rate, significant research has been focused on finding alternative treatments which do not involve the use of antibiotics. The promotion of beneficial gut bacteria can increase the resistance of animals to possible intestinal infections. Probiotics can be administered to humans or animals, offering preventive benefits of protecting the host from various types of intestinal diseases, providing positive effects on digestive processes and stimulating influence on the growth of organism, strengthening the barrier function of the gut microbiota and/or non-specific enhancement of the immune system. A study was designed to screen potential probiotic Bifidobacterium spp. strains with the ability to multiply in the intestine of weaned piglets and then to assess their health promoting effects when challenged with two enteric pathogens. Three series of trials were conducted with 60 weaning pigs fed one of 12 different Bifidobacterium spp. strains either once or twice a day. The most effective probiotic treatment (Bifidobacterium animalis subsp. lactis, strain Ra 18, at a dose of 1011cfu twice a day) was then challenged in two series of experiments with the enteric pathogens, Salmonella enterica serovar typhimurium and E. coli K88. Bifidobacterium animalis subsp. lactis strain Ra 18 significantly increased (p<0.01) the number of viable bifidobacteria in the cecum contents. When it was challenged with Salmonella, Ra 18 reduced excretion of this pathogen with the faeces. On the whole, supplementation with Ra 18 had a positive effect on the growth performance of pigs except after challenge with E. coli K88 where pigs susceptible to ETEC adhesion were lighter than pigs not susceptible

Antimicrobial effect of dietary nitrate in weaning piglets challenged or not with Salmonella enterica serovar typhimurium

The maintenance of a beneficial bacteria balance in the gut is important to increase the animal’s resistance to diseases. Nitrite may kill gut pathogens representing a non-immune defence mechanism. Nitrite can be derived from dietary nitrate that is reduced under the acidic conditions of the oral cavity. An in vivo study was designed in order to establish the antimicrobial effects of dietary nitrate on the gut microbiota and on the health of 96 weaning piglets. The pigs were fed a diet containing high levels of nitrate (15 mg/kg feed and 150 mg/kg feed) and then challenged with Salmonella enterica serovar typhimurium. Changes of the intestinal microbiota composition were assessed by analysing the stomach and jejunum contents from all the pigs. Results showed that nitrate only affected the population levels of Lactic Acid Bacteria (LAB) in both segments. Pigs challenged with Salmonella showed a reduction in the levels of E. coli and clostridia in the jejunum suggesting a mechanism of competition for niches or for active sites. The time from challenge significantly decreased the number of LAB in stomach and jejunum. It also decreased the population density of clostridia in the stomach. The supplementation of feedstuff with high dietary nitrate intake contemporarily to the challenge with Salmonella did not affect the degree of ulceration in the pigs

The potential of bifidobacteria as a source of natural folate

Aims: To screen 19 strains of bifidobacteria for main folate forms composition in synthetic folate-free and complex folate-containing media. Methods and Results: HPLC was used to analyse deconjugated folates extracted from bacterial biomass. Most strains had a total folate content above 4000 mu g per 100 g dry matter (DM). The highest value of 9295 mu g per 100 g DM was found in Bifidobacterium catenulatum ATCC 27539 and the lowest in Bifidobacterium animalis ssp. animalis ATCC 25527 containing 220 mu g per 100 g DM. Ten strains grew in a synthetic folate-free medium (FFM), showing folate autotrophy and suggesting folate auxotrophy of the remaining nine. In the autotrophic strains, a consistently higher folate level was found in FFM as compared to a more complex folate-containing medium, suggesting reduced requirements for folates in the presence of growth factors otherwise requiring folates for synthesis. The contents of total folate, 5-CH3-H(4)folate and H(4)folate were strain dependent. 5-CH3-H(4)folate dominated in most strains. Conclusions: Our results show that bifidobacteria folate content and composition is dynamic, is strain specific and depends on the medium. Suitable selection of the growth conditions can result in high levels of folate per cell unit biomass. Significance and Impact of the Study: This suggests that certain bifidobacteria may contribute to the folate intake, either directly in foods, such as fermented dairy products, or in the intestine as folate-trophic probiotics or part of the natural microbiota

Biosynthesis and cellular content of folate in bifidobacteria across host species with different diets

Background: Bifidobacteria, one of the most common bacteria of the intestinal tract, help establish balance in the gut microbiota and confer health benefits to the host. One beneficial property is folate biosynthesis, which is dependent on species and strains. It is unclear whether the diversity in folate biosynthesis is due to the adaptation of the bifidobacteria to the host diet or whether it is related to the phylogeny of the animal host. To date, folate production has been studied in the bifidobacteria of omnivorous, and a few herbivorous, non-primate hosts and humans, but not in carnivores, non-human primates and insects. In our study we screened folate content and composition in bifidobacteria isolated from carnivores (dog and cheetah), Hominoidea omnivorous non-human primates (chimpanzee and orangutan) and nectarivorous insects (honey bee). Results: Bifidobacterium pseudolongum subsp. globosum, a species typically found in non-primates, was isolated from dog and cheetah, and Bifidobacterium adolescentis and Bifidobacterium dentium, species typically found in humans, were respectively obtained from orangutan and chimpanzee. Evidence of folate biosynthesis was found in bifidobacteria isolated from non-human primates, but not from the bifidobacteria of carnivores and honey-bee. On comparing species from different hosts, such as poultry and herbivorous/omnivorous non-primates, it would appear that folate production is characteristic of primate (human and non-human) bifidobacteria but not of non-primate. Isolates from orangutan and chimpanzee had a high total folate content, the mean values being 7792 mu g/100 g dry matter (DM) for chimpanzee and 8368 mu g/100 g DM for orangutan. The tetrahydrofolate (H(4)folate) and 5-niethyl-tetrahydrofolate (5-CH3-H(4)folate) distribution varied in the bifidobacteria of the different animal species, but remained similar in the strains of the same species: B. dentium CHZ9 contained the least 5-CH3-H(4)folate (3749 mu/100 g DM), while B. adolescentis ORG10 contained the most (8210 mu g/100 g DM). Conclusion: Our data suggest a correlation between phylogenetic lineage and capacity of folate production by bifidobacteria, rather than with dietary type of the host