Selection of Bacillus species for targeted in situ release of prebiotic galacto-rhamnogalacturonan from potato pulp in piglets

We have previously shown that galacto-rhamnogalacturonan fibers can be enzymatically extracted from potato pulp and that these fibers have potential for exerting a prebiotic effect in piglets. The spore-forming Bacillus species are widely used as probiotics in feed supplements for pigs. In this study, we evaluated the option for further functionalizing Bacillus feed supplements by selecting strains possessing the enzymes required for extraction of the potentially prebiotic fibers. We established that it would require production and secretion of pectin lyase and/or polygalacturonase but no or limited secretion of galactanase and β-galactosidase. By screening a library of 158 Bacillus species isolated from feces and soil, we demonstrated that especially strains of Bacillus amyloliquefaciens, Bacillus subtilis, and Bacillus mojavensis have the necessary enzyme profile and thus the capability to degrade polygalacturonan. Using an in vitro porcine gastrointestinal model system, we revealed that specifically strains of B. mojavensis were able to efficiently release galacto-rhamnogalacturonan from potato pulp under simulated gastrointestinal conditions. The work thus demonstrated the feasibility of producing prebiotic fibers via a feed containing Bacillus spores and potato pulp and identified candidates for future in vivo evaluation in piglets.

     

The effect of growth media and physical treatments on the adhesion properties of canine probiotics

Aims

The manufacturing processes have been reported to influence the properties of probiotics with potential impact on health properties. The aim was to investigate the effect of different growth media and inactivation methods on the properties of canine‐originated probiotic bacteria alone and in combination mixture.

Methods and Results

Three established dog probiotics, Lactobacillus fermentum VET9A, Lactobacillus plantarum VET14A and Lactobacillus rhamnosus VET16A, and their combination mixture were evaluated for their adhesion to dog mucus. The effect of different growth media, one reflecting laboratory and the other manufacturing conditions, and inactivation methods (95°C, 80°C and UV irradiation) on the mucus adhesion of the probiotic strains was characterized. Evaluation of dog probiotics was supported by cell visualization using transmission electron microscopy (TEM). Higher adhesion percentage was reported for probiotic strains growing in laboratory rather than in manufacturing conditions (P < 0·05). Inactivation by heat (95°C, 80°C) decreased the adhesion properties when strains were cultivated in soy‐based growth media compared with those grown in MRS broth (P < 0·05). TEM observations uncovered differences in cell‐surface components in nonviable forms of probiotic strains as compared with their viable forms.

Conclusions

Manufacturing process conditions such as growth media and pretreatment methods may significantly affect the adhesive ability of the tested strains.

Significance and Impact of the Study

Growth conditions, growth media, pretreatment methods and different probiotic combinations should be carefully considered for quality control of existing probiotics and for identification of new probiotics for dogs. These may also have an impact on health benefits for the host.     

Germination and outgrowth of Bacillus subtilis and Bacillus licheniformis spores in the gastrointestinal tract of pigs

Aims: To determine if orally ingested Bacillus spores used as probiotics or direct‐fed microbial feed additives germinate and the vegetative cells grow in the gastrointestinal (GI) tract. Methods and Results: Three independent experiments were done to determine if spores of Bacillus licheniformis and Bacillus subtilis germinate and grow in the GI tract of pigs. After a 2 weeks spore‐feeding period, spores were detected in all segments of the GI tract. The lowest number of spores was found in the stomach, increasing in the small intestine to approx. 55% of the dietary inclusion. When spores were withdrawn from the feed, faecal excretion of spores reflected the dietary inclusion, but decreased gradually to the background level after 1 week. By containing spores in short, sealed pieces of dialysis membrane that were orally administered to the pigs, both the number of spores and vegetative cells could be determined by flow cytometry. Spores accounted for 72% of the total counts after 4–6 h in the stomach and proximal part of the small intestine. After 24 h, spores constituted only 12% of the total counts in the stomach, caecum, and mid‐colon. Less spores and more vegetative cells were detected after 24 h, but total counts increased only 2·14‐fold compared to time zero. Conclusions: The experiments showed that 70–90% of dietary‐supplemented Bacillus spores germinate in the proximal part of the pig GI tract, and that only limited outgrowth of the vegetative cell population occurs. The two Bacillus strains can temporarily remain in the GI system, but will be unable to permanently colonize the GI tract. Significance and Impact of the Study: A substantial population of growing vegetative cells in the GI tract is not a prerequisite for the mode of action of Bacillus feed additives and probiotics.     

益生菌调控胃肠道菌群改善肉品质的研究进展

胃肠道菌群对动物健康和生产性能起到重要作用。将益生菌应用于畜禽养殖可调节肠道微生态平衡,调控脂肪代谢,提高饲料利用率以及促进风味物质形成等多种途径提高畜禽肉的品质。本文综述了不同益生菌调节胃肠道微生态的机理,并通过改善肠道菌群结构来改善畜禽肉的品质,为进一步研究开发以胃肠道菌群为靶点的益生菌饲料提供参考。     

Anti-Adhesion Effects of Lactobacillus Strains on Caco-2 Cells Against Escherichia Coli and Their Application in Ameliorating the Symptoms of Dextran Sulfate Sodium-Induced Colitis in Mice

The beneficial effects of probiotics on ameliorating ulcerative colitis (UC) have attracted much attention in recent years. Nevertheless, the number of these identified probiotics is still limited. In addition, the adhesion abilities of probiotics are considered to be a key determinant for probiotic efficacy. However, the relationship between the adhesion abilities of probiotics and their role in ameliorating UC has been poorly studied to date. This study measured the adhesion abilities of four Lactobacillus strains to Caco-2 cells and their anti-adhesion effects on Caco-2 cells against pathogenic bacteria, as well as their application in ameliorating the symptoms of dextran sulfate sodium-induced UC, and further illustrated the relationship between these two potential probiotic properties of probiotics and their beneficial effects on UC. Results suggested that the adhesion abilities of the four tested Lactobacillus strains exists highly strain-specific and the mechanisms of their anti-adhesion effect on Caco-2 cells against Escherichia coli may be different. Moreover, all these strains had promising effects on ameliorating UC by reducing inflammatory response and improving the intestinal mucosal barrier function, as well as promoting the production of SCFAs. In conclusion, the four tested Lactobacillus strains can be considered as alternative dietary supplements in alleviating UC. In addition, it could be concluded that there is no significant correlation between the adhesion abilities of probiotics and their role in ameliorating UC, which further illustrated that the adhesion properties of probiotics in vitro may not be suitable as the key criterion for screening potential strains with UC-alleviating effects.

     

Screening and selection of novel animal probiotics isolated from bovine chyme

Probiotics, gut-colonizing microorganisms capable of conferring a number of health benefits to their hosts, are highly desirable as animal feed supplements. Members of the Gram-positive genus Bacillus are often utilized as probiotics, since endospores formed by those bacteria render them highly resistant to environmental extremes and therefore capable of surviving gastrointestinal tract conditions. In this study, 84 distinct bacterial colonies were obtained from bovine chyme and 29 isolates were determined as Bacillus species. These isolates were principally screened for their antimicrobial activity against a group of two Gram-positive and four Gram-negative bacteria, including known human and animal pathogens such as Salmonella enterica, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Seven strains displaying strong antimicrobial activity against the test cohort were further evaluated for other properties desirable from animal probiotics, including high spore-forming capacity and adhesiveness, resistance to pH extremes and ability to form biofilms. The isolates were found to resist simulated gastrointestinal conditions and most of the antibiotics tested. In addition, plasmid presence was checked and cytotoxicity tests were performed to evaluate the potential risks of antibiotic resistance transfer and unintended pathogenic effects on host, respectively. We propose that the bacterial isolates are suitable for use as animal probiotics.     

In vitro inhibitory activity of probiotic spore-forming bacilli against genotoxins

Aims: To investigate the ability of bacilli of various species (Bacillus clausii, Bacillus subtilis, Bacillus lentus, Bacillus pumilus. Bacillus megaterium, Bacillus firmus, Bacillus sp.) and origins (probiotic and collection strains) to counteract the activity of some representative DNA‐reactive agents. Methods and Results: The inhibitory effect of 21 bacilli strains, previously characterized by tDNA‐PCR, on four genotoxins, was examined in vitro using the short‐term assay SOS‐Chromotest. All strains had a high inhibitory activity against 4‐nitroquinoline‐1‐oxide and N‐methyl‐N′‐nitro‐nitrosoguanidine (direct agents), whereas the inhibitory activity was high or moderate against 2‐amino‐3,4‐dimethylimidazo[4,5‐f]quinoline and aflatoxin B1 (indirect agents). Antigenotoxicity was observed in vegetative cells, but not heat‐treated cells or spore suspensions. The spectroscopic properties of compounds were modified after cell co‐incubation and all the strains maintained high viability after exposure to the genotoxins. Conclusions: No relevant differences in antigenotoxicity were evidenced among strains of the examined species or between probiotic and collection strains. Significance and Impact of the Study: Although derived from an in vitro model, the results suggest that Bacillus‐based probiotics could be useful for reducing the gastrointestinal risk originating from genotoxic agents.     

Butanol production from corncob residue using Clostridium beijerinckii NCIMB 8052

Aims: Not all lactic acid bacteria possess the ability to confer health benefits for the host. Thus, it becomes necessary to screen and characterize numerous strains to obtain ideal probiotics. Here, two Lactobacillus plantarum strains (CECT 7315 and CECT 7316) were isolated and characterized. Methods and Results: In vitro and in vivo tests were carried out for demonstrating the abilities as probiotics of CECT 7315/CECT 7316 Lact. plantarum strains. Both strains showed high ability to survive at gastro‐intestinal tract conditions and to adhere to intestinal epithelial cells, as well as great inhibitory activity against a wide range of enteropathogens and ability to induce the production of anti‐inflammatory cytokine IL‐10. Conclusions: Lactobacillus plantarum CECT 7315/CECT 7316 because of their potential probiotic properties could be excellent candidates for being tested in clinical trials aimed to demonstrate beneficial effects on human health. Significance and Impact of the Study: Probiotics are live micro‐organisms that confer a health benefit for the host. However, not all the lactic acid bacteria possess the ability to confer health benefits for the host. In this study, two Lact. plantarum strains (CECT 7315 and CECT 7316) were isolated and characterized to demonstrate their excellent qualities as potential probiotic strains.     

Administration of host‐derived probiotics does not affect utilization of soybean meal enriched diets in juvenile turbot (Scophthalmus maximus)

In today's aquaculture, the cost‐intensive and scarce fishmeal is increasingly replaced by plant‐based feedstuff such as soybean meal (SBM). However, SBM contains saponins which can have adverse effects on fish's digestive tract potentially culminating in severe enteritis. In a 60 day feeding trial we studied the use of autochthonous bacteria as probiotics upon SBM supplementation on juvenile turbot. Growth performance, feed conversion, body composition and health status were assessed for five different treatment groups, comprising a fishmeal control (FM ctrl), a SBM control without probiotics (SBM ctrl) and three multi‐species probiotic treatments. For the production of the probiotic treatments a basal diet with a composition identical to the SBM ctrl including 40% SBM of total dry matter likewise was prepared. The basal diet was stepwise top coated with three different probiotic supplementations: (a) three distinct isolates with saponin‐metabolizing ability (SBM + degrad); (b) three distinct isolates inhibitory towards the pathogen, Tenacibaculum maritimum (SBM + anta); and (c) a commercial probiotic application (SBM + com). Individual weight gain was highest in FM ctrl but only SBM + degrad diet showed a significantly lower value (p < 0.05). The feed conversion ratio was lowest in FM ctrl and significantly higher in SBM + degrad (p < 0.01). The protein retention efficiency did only differ significantly between FM ctrl and SBM + degrad (p < 0.05), whereas lipid retention efficiency remained unaffected. Whole body composition and gross energy content were similar in all treatments lacking significant differences. The condition factor was significantly elevated in SBM + degrad compared to FM ctrl (p < 0.05). Hematocrit was highest in FM ctrl and significantly lower in the other treatments (p < 0.01) with SBM + com accounting for the lowest value (p < 0.001). The hepatosomatic index was slightly increased in FM ctrl but no significant difference was detected. Regarding the spleen somatic index SBM + anta treatment revealed the highest and SBM ctrl a significantly lower value (p < 0.05). In conclusion, the growth performance of fish did not benefit from the different probiotic treatments, while body composition and gross energy content remained at an appropriate level. Moreover, the overall health status was on a sufficient level in all treatments which confirms the high dietary tolerability of our putative probiotic isolates by the fish.     

Potential probiotic strains with heavy metals and mycotoxins bioremoval capacity for application in foodstuffs

Heavy metals and mycotoxins in foodstuffs are one of the major concerns of our world nowadays. Food decontamination with the help of microbial biomass is a cheap, easy, efficient and green method known as bioremoval. Probiotics are able to reduce the availability of heavy metals and toxins in food products. The purpose of this review is to summarize the probiotics and potential probiotics' interesting role in food bio-decontamination. After a brief glance at the definition of potential probiotic strains with bioremoval ability, LABs (lactic acid bacteria) are described as they are the most important groups of probiotics. After that, the role of the main probiotic and potential probiotic strains (Bacillus, Lactobacillus, Lactococcus, Enterococcus, Bifidobacterium, Pediococcus, Propionibacterium, Streptococcus and Saccharomyces cerevisiae) for heavy metals and mycotoxins bioremoval are described. Additionally, the bioremoval mechanism and the effect of some factors in bioremoval efficiency are explained. Finally, the investigations about probiotic and contaminant stability are mentioned. It is worth mentioning that this review article can be exerted in different food and beverage industries to eliminate the heavy metals and mycotoxins in foodstuffs.     

Probiotic consortia are not uniformly effective against different amphibian chytrid pathogen isolates

Symbiotic bacterial communities can protect their hosts from infection by pathogens. Treatment of wild individuals with protective bacteria (probiotics) isolated from hosts can combat the spread of emerging infectious diseases. However, it is unclear whether candidate probiotic bacteria can offer consistent protection across multiple isolates of globally distributed pathogens. Here, we use the lethal amphibian fungal pathogen Batrachochytrium dendrobatidis to investigate whether probiotic richness (number of bacteria) or genetic distance among consortia members influences broad‐scale in vitro inhibitory capabilities of probiotics across multiple isolates of the pathogen. We show that inhibition of multiple pathogen isolates by individual bacteria is rare, with no systematic pattern among bacterial genera in ability to inhibit multiple B. dendrobatidis isolates. Bacterial consortia can offer stronger protection against B. dendrobatidis compared to single strains, and this tended to be more pronounced for consortia containing multiple genera compared with those consisting of bacteria from a single genus (i.e., with lower genetic distance), but critically, this effect was not uniform across all B. dendrobatidis isolates. These novel insights have important implications for the effective design of bacterial probiotics to mitigate emerging infectious diseases.     

Endospore production of Bacillus spp. for industrial use

The increased occurrence of antibiotic resistance and the harmful use of pesticides are a major problem of modern times. A ban on the use of antibiotics as growth promoters in animal breeding has put a focus on the probiotics market. Probiotic food supplements are versatile and show promising results in animal and human nutrition. Chemical pesticides can be substituted by biopesticides, which are very effective against various pests in plants due to increased research. What these fields have in common is the use of spore-forming bacteria. The endospore-forming Bacillus spp. belonging to this group offer an effective solution to the aforementioned problems. Therefore, the biotechnological production of sufficient qualities of such endospores has become an innovative and financially viable field of research. In this review, the production of different Bacillus spp. endospores will be reviewed. For this purpose, the media compositions, cultivation conditions and bioprocess optimization methods of the last 20 years are presented and reflected.     

Applications and safety considerations of Lactobacillus salivarius as a probiotic in animal and human health

The goals of this review are to summarize the current knowledge on the application of Lactobacillus salivarius as a probiotic in animals and humans, and to address safety concerns with its use on live hosts. Overall, several strains of L. salivarius are well established probiotics with multiple applications in animal health, particularly to reduce colonization by gastrointestinal pathogens, and to a lesser extent, as a production and quality aid. In humans, L. salivarius has been used to prevent and treat a variety of chronic diseases, including asthma, cancer, atopic dermatitis and halitosis, and to a much limited extent, to prevent or treat infections. Based on the results from primary research evidence, it seems that L. salivarius does not pose a health risk to animals or humans in the doses currently used for a variety of applications; however, there is a systematic lack of studies assuring the safety of many of the strains intended for clinical use. This review provides researchers in the field with up‐to‐date information regarding applications and safety of L. salivarius. Furthermore, it helps researchers identify knowledge gaps and potential opportunities for microbiological and clinical research.     

Controlling and Defence‐related Mechanisms of Bacillus Strains Against Bacterial Leaf Blight of Rice

Bacillus strains are broadly studied for their beneficial role in plant growth and biological control of plant disease and pest; however, little is known about their underlying mechanisms. In this study, we assessed the controlling and defence‐related mechanisms of three Bacillus strains including rice seed‐associated strain B. subtilis A15, rhizobacterial strains B. amyloliquefaciens D29 and B. methylotrophicus H8, all of which are against bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae. Results indicated that all three strains showed strong biofilm formation ability. The culture filtrates of each strain significantly suppressed the growth and biofilm formation of X. oryzae, while changes in bacterial cell morphology such as cell swell and severe cell wall alterations were observed through the transmission electron microscopy images. PCR analysis revealed that all three strains harbour the antimicrobial‐associated genes that are responsible for biosynthesis of bacillomycin, fengycin, iturin and surfactin. Subsequent real‐time qPCR analysis revealed the upregulated expression of fenD and srfAA genes in D29 and H8, and fenD and ituC genes in A15 during their in vitro interaction with X. oryzae. It suggests that the antibacterial mechanisms of the three strains may be at least partially associated with their ability to secrete corresponding lipopeptides. Interestingly, the applications of the three strains in greenhouse conditions were found to be effective in controlling the BLB disease, which was achieved through the activation of inducing systemic resistance resulted from the enhanced activities of defence‐related enzymes. This is the first report of demonstration of the mode of antibacterial effect of Bacillus strains against X. oryzae. Overall, data from the current study provide valuable information for biological control of BLB disease in rice.     

Differentiation of probiotic and environmental Saccharomyces cerevisiae strains in animal feed

Aims: To establish an identification system for probiotic Saccharomyces cerevisiae strains based on artificial neural network (ANN)–assisted Fourier‐transform infrared (FTIR) spectroscopy to improve quality control of animal feed. Methods and Results: The ANN‐based system for differentiating environmental from probiotic S. cerevisiae strains comprises five authorized feed additive strains plus environmental strains isolated from different habitats. A total of 108 isolates were used as reference strains to create the ANN. DHPLC analysis and δ‐PCR were used as reference methods to type probiotic yeast isolates. The performance of the FTIR‐ANN was tested in an internal validation using unknown spectra of each reference strain. This validation step yielded a classification rate of 99·1 %. For an external validation, a test data set comprising 965 spectra of 63 probiotic and environmental S. cerevisiae isolates unknown to the ANN was used, resulting in a classification rate of 98·2 %. Conclusions: Our results demonstrate that probiotic S. cerevisiae strains in feed can be differentiated successfully from environmental isolates using both genotypic approaches and ANN‐based FTIR spectroscopy. Significance and Impact of the Study: FTIR‐based artificial neural network analysis provides a rapid and inexpensive technique for yeast identification both at the species and at the strain level in routine diagnostic laboratories, using a single sample preparation.     

Colonization ability as an indicator of enhanced biocontrol capacity—An example using two Bacillus amyloliquefaciens strains and Botrytis cinerea infection of tomatoes

An understanding of biocontrol activities is important when developing microorganism‐based alternatives to conventional fungicides. From our bacterial collection, we selected two strains (BBC023 and BBC047) for their outstanding antagonistic capacity against fungal phytopathogens and growth‐promoting abilities towards Arabidopsis thaliana. According to physiological and molecular characterizations, both strains were classified as Bacillus amyloliquefaciens and were tested against Botrytis cinerea in vitro and in a tomato. Both strains secrete lipopeptide‐like compounds that contribute to their in vitro antagonism. SEM‐images showed altered B. cinerea mycelial structures that were consistent with previous reports of the direct action of lipopeptides against fungal hyphae. The strains were applied to the roots (R), leaves (foliar ‐ F) or root/leaves (R/F) on tomato plants. All treatments significantly reduced the severity of B. cinerea infection (measured as a control index). However, only root applications (R and R/F) led to growth promotion in the tomato plants. We detected the production of indole acetic acid (IAA) and 2,3‐butanediol as growth promotion traits in the two strains. For both strains, the R/F treatment showed the highest control index, suggesting a synergic effect of direct antagonism against B. cinerea and resistance induction in the plant. In addition, in vitro antagonism of BBC023 and BBC047 against B. cinerea was similar; whereas in the F application, strain BBC047 significantly improved plant resistance and maintained a higher population density over time on tomato leaves, compared to BBC023. BBC047 was also able to produce a complex and robust biofilm in Msgg medium compared with that of BBC023. We linked the reduced biocontrol of BBC023 on leaves with its limited ability to generate robust biofilms and colonize the phylloplane. At last, we highlight the potential of the native Bacillus strains as promising alternatives for the development of bioproducts for sustainable agriculture.     

Multistrain probiotic production by co‐culture fermentation in a lab‐scale bioreactor

Most commercial probiotic products intended for pharmaceutical applications consist of combinations of probiotic strains and are available in various forms. The development of co‐culture fermentation conditions to produce probiotics with the correct proportion of viable microorganisms would reduce multiple operations and the associated costs. The aim of this study was to develop a fermentation medium and process to achieve biomass comprising the desired proportion of two probiotic strains in co‐culture. Initially, a quantification medium was developed, and the method was optimized to allow the quantification of each strain's biomass in a mixture. The specific growth rates of Lactobacillus delbrueckii spp. bulgaricus and Lactobacillus plantarum were determined in media with different carbon sources. The inoculum volume was optimized to achieve equal proportion of biomass in co‐culture fermentation in test tubes. Next, fermentation was carried out in a 3‐L bioreactor. A biomass concentration of 2.06 g/L, with L. delbrueckii spp. bulgaricus and L. plantarum in the ratio of 47%:53% (by weight), was achieved with concomitant production of 12.69 g/L of lactic acid in 14 h. The results show that with careful manipulation of process conditions, it is possible to achieve the desired proportion of individual strains in the final biomass produced by co‐culture fermentation. This process may serve as a model to produce multistrain probiotic drugs at industrial scale.     

Probiotic roles of Lactobacillus sp. in swine: insights from gut microbiota

The use of lactobacilli as probiotics in swine has been gaining attention due to their ability to improve growth performance and carcass quality, prevent gastrointestinal infection and most importantly, their ‘generally recognized as safe’ status. Previous studies support the potential of lactobacilli to regulate host immune systems, enhance gut metabolic capacities and maintain balance in the gut microbiota. Research on swine gut microbiota has revealed complex gut microbial community structure and showed the importance of Lactobacillus to the host's health. However, the species‐ and strain‐specific characteristics of lactobacilli that confer probiotic benefits are still not well understood. The diversity of probiotic traits in a complex gut ecosystem makes it challenging to infer the relationships between specific functions of Lactobacillus sp. and host health. In this review, we provide an overview of how lactobacilli play a pivotal role in the swine gut ecosystem and identify key characteristics that influence gut microbial community structure and the health of pigs. In addition, based on recent and ongoing meta‐omics and omics research on the gut microbiota of pigs, we suggest a workflow combining culture‐dependent and culture‐independent approaches for more effective selection of probiotic lactobacilli.     

Fibrolytic Bacteria Isolated from the Rumen of North American Moose (Alces alces) and Their Use as a Probiotic in Neonatal Lambs

Fibrolytic bacteria were isolated from the rumen of North American moose (Alces alces), which eat a high-fiber diet of woody browse. It was hypothesized that fibrolytic bacteria isolated from the moose rumen could be used as probiotics to improve fiber degradation and animal production. Thirty-one isolates (Bacillus, n = 26; Paenibacillus, n = 1; and Staphylococcus, n = 4) were cultured from moose rumen digesta samples collected in Vermont. Using Sanger sequencing of the 16S rRNA gene, culturing techniques, and optical densities, isolates were identified and screened for biochemical properties important to plant carbohydrate degradation. Five isolates were selected as candidates for use as a probiotic, which was administered daily to neonate lambs for 9 weeks. It was hypothesized that regular administration of a probiotic to improve fibrolysis to neonate animals through weaning would increase the developing rumen bacterial diversity, increase animal production, and allow for long-term colonization of the probiotic species. Neither weight gain nor wool quality was improved in lambs given a probiotic, however, dietary efficiency was increased as evidenced by the reduced feed intake (and rearing costs) without a loss to weight gain. Experimental lambs had a lower acetate to propionate ratio than control lambs, which was previously shown to indicate increased dietary efficiency. Fibrolytic bacteria made up the majority of sequences, mainly Prevotella, Butyrivibrio, and Ruminococcus. While protozoal densities increased over time and were stable, methanogen densities varied greatly in the first six months of life for lambs. This is likely due to the changing diet and bacterial populations in the developing rumen.     

Immunostimulatory activity of potential probiotic yeast strains in the dorsal air pouch system and the gut mucosa

Aims: To determine the immunostimulatory activity of 15 presumptive probiotic yeast strains in the dorsal air pouch system in comparison with their activity in the gut mucosa. Methods and Results: Presumptive probiotic yeast strains previously isolated from human gastrointestinal tract and Feta cheese were further characterized genotypically and biochemically. The Saccharomyces cerevisiae 982, Saccharomyces boulardii KK1 and Kluyveromyces lactis 630 strains exhibited in the air pouch increased polymorphonuclear cell influx and phagocytic activity as well as cytokine production with similar potency as the probiotics Ultra levure S. boulardii and Lactobacillus acidophilus NCFB 1748. Oral administration of these strains in mice results in differential activation of small intestine immune responses concerning IgA and cytokine production as well as Toll‐like receptor expression. Conclusion: Besides the Saccharomyces strains 982 and KK1, the K. lactis 630 strain could also be considered as a candidate probiotic. Significance and Impact of the Study: The air pouch model may be used as an alternative and rapid method for the discrimination and selection of potential probiotic yeast strains.