Use of Yeast Probiotics in Ruminants: Effects and Mechanisms of Action on Rumen pH, Fibre Degradation, and Microbiota According to the Diet

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Production of maltodextrin 1-Phosphate by Fibrobacter succinogenes S85

We show for the first time the occurrence of maltodextrin-1-Phosphate (MD-1P) (DP 2) in F. succinogenes S85, a rumen bacterium specialized in cellulolysis which is not able to use maltose and starch. MD-1P were found in intra and extracellular medium of resting cells incubated with glucose. We used 2D 1H NMR technique and TLC to identify their structure and quantify their production with time. It was also shown that these phosphorylated oligosaccharides originated both from exogenous glucose and endogenous glycoge

NMR study of cellulose and wheat straw degradation by Ruminococcus albus 20

Cellulose and wheat straw degradation by Ruminococcus albus was monitored using NMR spectroscopy. In situ solid-state 13C-cross-polarization magic angle spinning NMR was used to monitor the modification of the composition and structure of cellulose and 13C-enriched wheat straw during the growth of the bacterium on these substrates. In cellulose, amorphous regions were not preferentially degraded relative to crystalline areas by R. albus. Cellulose and hemicelluloses were also degraded at the same rate in wheat straw. Liquid state two-dimensional NMR experiments were used to analyse in detail the sugars released in the culture medium, and the integration of NMR signals enabled their quantification at various times of culture. The results showed glucose and cellodextrin accumulation in the medium of cellulose cultures; the cellodextrins were mainly cellotriose and accumulated to up to 2 mm after 4 days. In the wheat straw cultures, xylose was the main soluble sugar detected (1.4 mm); arabinose and glucose were also found, together with some oligosaccharides liberated from hemicellulose hydrolysis, but to a much lesser extent. No cellodextrins were detected. The results indicate that this strain of R. albus is unable to use glucose, xylose and arabinose for growth, but utilizes efficiently xylooligosaccharides. R. albus 20 appears to be less efficient than Fibrobacter succinogenes S85 for the degradation of wheat stra

Experimental models to study intestinal microbes-mucus interactions in health and disease

A close symbiotic relationship exists between the intestinal microbiota and its host. A critical component of gut homeostasis is the presence of a mucus layer covering the gastrointestinal tract. Mucus is a viscoelastic gel at the interface between the luminal content and the host tissue that provides a habitat to the gut microbiota and protects the intestinal epithelium. The review starts by setting up the biological context underpinning the need for experimental models to study gut bacteria-mucus interactions in the digestive environment. We provide an overview of the structure and function of intestinal mucus and mucins, their interactions with intestinal bacteria (including commensal, probiotics and pathogenic microorganisms) and their role in modulating health and disease states. We then describe the characteristics and potentials of experimental models currently available to study the mechanisms underpinning the interaction of mucus with gut microbes, including in vitro, ex vivo and in vivo models. We then discuss the limitations and challenges facing this field of research

Addressing global ruminant agricultural challenges through understanding the rumen microbiome::Past, present and future

The rumen is a complex ecosystem composed of anaerobic bacteria, protozoa, fungi, methanogenic archaea and phages. These microbes interact closely to breakdown plant material that cannot be digested by humans, whilst providing metabolic energy to the host and, in the case of archaea, producing methane. Consequently, ruminants produce meat and milk, which are rich in high-quality protein, vitamins and minerals, and therefore contribute to food security. As the world population is predicted to reach approximately 9.7 billion by 2050, an increase in ruminant production to satisfy global protein demand is necessary, despite limited land availability, and whilst ensuring environmental impact is minimized. Although challenging, these goals can be met, but depend on our understanding of the rumen microbiome. Attempts to manipulate the rumen microbiome to benefit global agricultural challenges have been ongoing for decades with limited success, mostly due to the lack of a detailed understanding of this microbiome and our limited ability to culture most of these microbes outside the rumen. The potential to manipulate the rumen microbiome and meet global livestock challenges through animal breeding and introduction of dietary interventions during early life have recently emerged as promising new technologies. Our inability to phenotype ruminants in a high-throughput manner has also hampered progress, although the recent increase in “omic” data may allow further development of mathematical models and rumen microbial gene biomarkers as proxies. Advances in computational tools, high-throughput sequencing technologies and cultivation-independent “omics” approaches continue to revolutionize our understanding of the rumen microbiome. This will ultimately provide the knowledge framework needed to solve current and future ruminant livestock challenges

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Effets de la monensine sur les gradients transmembranaires de H+, Na+ et K+ chez Bacteroides succinogenes. bactérie cellulolytique du rumen

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Viande bovine. E. Qualité sanitaire microbiologique de la viande bovine

Partie 2 - Déterminants alimentaires et non alimentaires en élevage de la qualité des produits (Chapitre 7)National audienc