The species and physiological diversity of Bifidobacterium genus in Gallus gallus domesticus are influenced by feeding model and niche adaptations.

Species diversity of the Bifidobacterium genus was scarcely explored in different rearing systems of poultry. The aim of the study was to isolate intestinal species and compare their physiological and traits for adaptation to the avian intestinal niche. Fourteen strains isolated from chickens of intensive rearing farms and free-range hens, were identified by 16S rDNA sequencing, rep-PCR fingerprinting, and carbohydrates fermentation. Strains belonged to species Bifidobacterium pseudolongum subsp. pseudolongum and subsp. globosum, B. pullorum, B. animalis subsp lactis, B. boum, B. thermacidophilum subsp. thermacidophilum and B. thermophilum. One strain of B. animalis and B. pullorum, and two of B. pseudolongum subsp. pseudolongum were obtained from chicks, while the others were from free-range adult hens. Growth (in MRSc) at the poultry physiological temperature, acids production in caecal water with raffinose (rCW), ex vivo adhesion (%) to avian intestinal epithelial cells (IEC), and auto-aggregation (%) were used for discrimination inter- and intra-specific. Significantly different acetic and lactic acids production and growth temperatures were observed in strains of the same species/subspecies. Remarkable auto-aggregation capability was observed in B. thermacidophilum subsp. thermacidophilum LET 406 (40.2 ± 1.1%), while adhesion property was highlighted in B. pseudolongum subsp. pseudolongum LET 408 (65.30 ± 4.75% in jejunum; 46.05 ± 2.80 in ileum). Scanning Electronic Microscopy of the interaction IEC-LET 408 revealed an irregular bacterial surface exhibiting vesicle-like arrangements and filaments that formed a network among bacteria cells and with the epithelial cells, as possible adaptative response to promote its persistence in the gut. These finds will be valuable for bacterial supplements design intended to intensive rearing.

Lactic acid bacteria isolated from poultry protect the intestinal epithelial cells of chickens from in vitro wheat germ agglutinin-induced cytotoxicity.

Poultry fed on wheat-based diets regularly ingest wheat germ agglutinin (WGA) that has toxic effects in vitro on intestinal epithelial cells (IEC) obtained from 14-d-old broilers. Cytotoxicity and the potential role of 14 intestinal bacterial strains in the removal of bound lectins in epithelial cell cultures were investigated. Cytotoxicity was dependent on time and lectin concentration; the lethal dose (LD50) was 8.36 µg/ml for IEC exposed for 2 h to WGA. Complementary sugars to WGA were detected on the surface of one Enterococcus and 9 Lactobacillus strains isolated from poultry. These strains were evaluated as a lectin removal tool for cytotoxicity prevention. Incubation of lactic acid bacteria with WGA before IEC-lectin interaction caused a substantial reduction in the percentage of cell deaths. The protection was attributed to the amount of lectin bound to the bacterial surfaces and was strain-dependent. L. salivarius LET 201 and L. reuteri LET 210 were more efficient than the other lactic acid bacteria assayed. These results provide a basis for the development of probiotic supplements or cell-wall preparations of selected lactic acid bacteria intended to avoid harmful effects of a natural constituent of the grain in wheat-based diets.

Propionibacterium acidipropionici CRL1198 influences the production of acids and the growth of bacterial genera stimulated by inulin in a murine model of cecal slurries.

Different attempts have been made to improve the health status of humans and animals by increasing the intestinal production of short-chain fatty acids (SCFA) derived from non-digestible carbohydrates fermentation. In this paper we investigate the in vitro production of short-chain fatty acids (SCFA) after addition of inulin, propionibacteria or a combination of both in an experimental model of mice cecal slurries. The development of bacterial genera which are usually stimulated by inulin addition was also investigated. According to our experimental data, acetic acid and butyric acids concentrations increased after incubation in slurries that had no supplements. By contrast, butyric acid concentrations remained in the basal value when supplements were used. Fermentation of only inulin did not increase the concentration of total SCFA. Propionibacterium acidipropionici CRL1198 improved the production of propionic acid in cecal slurries when it was added alone, but the effect was more noticeable in the combination with inulin. A modulation of the global fermentative activity of the cecal microbiota was evidenced by the increase on the ratio propionic acid/SCFA in supplementations with propionibacteria. Statistical analysis of data demonstrated that samples from homogenates with propionibacteria alone or combined with inulin belong to the same cluster. The presence of propionibacteria limited the growth of Bacteroides fragilis and Clostridium hystoliticum groups in slurries with and without inulin. The growth of Bifidobacterium was not modified and the stimulating effect of inulin on lactobacilli disappeared in the presence of propionibacteria. In conclusion, dairy propionibacteria are potential candidates to develop new functional foods helpful to ensure the intestinal production of SCFA during inulin supplementation and to control the overgrowth of bacteria belonging to Bacteroides and Clostridium genera.

Conjugated linoleic acid conversion by dairy bacteria cultured in MRS broth and buffalo milk.

AIMS: To evaluate strains of Lactobacilli, Bifidobacteria and Streptococci for their ability to produce conjugated linoleic acid (CLA) from free linoleic acid (LA). METHODS AND RESULTS: Eight dairy bacteria tolerant to LA were grown in MRS broth containing LA (200 microg ml(-1)) and CLA was assessed. Seven bacteria were able to form CLA after 24 h of incubation, varying percentage conversion between 17% and 36%. Lactobacillus casei, Lactobacillus rhamnosus, Bifidobacterium bifidum and Streptococcus thermophilus showed the highest LA conversion and were inoculated into buffalo milk supplemented with different concentration of LA. The production of CLA at 200 microg ml(-1) of LA was two- or threefold in milk than MRS broth. All evaluated strains were able to produce CLA from high LA levels (1000 microg ml(-1)). CONCLUSIONS: The most tolerant strain to LA was Lact. casei. Lacttobacillus rhamnosus produced the maximum level of CLA at high LA concentrations (800 microg ml(-1)). The selected bacteria may be considered as adjunct cultures to be included on dairy fermented products manufacture. Low concentration of LA must be added to the medium to enhance CLA formation. SIGNIFICANCE AND IMPACT OF THE STUDY: The production of CLA by strains using milks from regional farms as medium offer a possible mechanism to enhance this beneficial compound in dairy products and those the possibility to develop functional foods.

Lactobacilli isolated from chicken intestines: potential use as probiotics.

Lactobacillus strains were tested for their in vitro probiotic properties. Cell surface hydrophobicity was found to be very high for Lactobacillus fermentum subsp. cellobiosus and Salmonella Gallinarum; high values could indicate a greater ability to adhere to epithelial cells. Studies on Lactobacillus animalis indicated relative cell surface hydrophobicities smaller than those of L. fermentum subsp. cellobiosus and L. fermentum. L. animalis and Enterococcus faecalis were able to coaggregate with L. fermentum subsp. cellobiosus and L. fermentum, respectively, but not with Salmonella Gallinarum. After mixed-culture studies for determining suitable growth behavior, the pair of strains L. animalis plus L. fermentum subsp. cellobiosus was selected for an attempted challenge against Salmonella Gallinarum. Double and triple mixed-culture studies indicated that selected lactobacillus strains were able to retain their beneficial characteristics in the presence of Salmonella Gallinarum such as presence of lectins, production of antimicrobial compounds, and ability to grow and compete. The selected microorganisms can be considered as potential ingredients for a chicken probiotic feed formulation intended to control salmonellosis and also improve poultry sanitation.

Short-chain fatty acids modulate growth of lactobacilli in mixed culture fermentations with propionibacteria.

Three strains of Lactobacillus (L. helveticus ATCC 15009 and CRL 581, and L casei LC 3) were paired with three strains of Propionibacterium (P. freudenreichii AP8, P. freudenreichii GP6 and P. acidipropionici CRL 756) and grown in individual and mixed cultures in a complex medium. Bacterial growth, carbohydrate consumption, and production of acids was determined and compared after mono and binary culture. Propionibacterium strains were inhibited in mixed cultures that rapidly reached low pH values, and stimulated in those with slow pH reduction. In several pairs Lactobacillus strains were stimulated by mixed cultivation, while in others they were unaffected or inhibited. Lactic acid reduction by Propionibacterium consumption was not always enough to produce a stimulatory effect on growth of lactobacilli. The behaviour of Lactobacillus strains in individual cultures in media with propionic acid was similar to that of mixed cultures with Propionibacterium. As propionic acid concentration increased in the medium and glucose was consumed, both individual and mixed cultures of lactobacilli showed inhibition of the growth and increase of the fermentation activity.