Isolation and characterization of Selenomonas ruminantium strains capable of 2-deoxyribose utilization

Effects of phenylpyruvate on the growth performance and intestinal microbiota in broiler chicken

1. The purpose of this study was to see how dietary supplementation with phenylpyruvate affected broiler growth, slaughter performance, gut health microbiota and immunity. This information can be used to develop alternative approaches to antibiotic replacement in modern poultry production and health.2. A total of 288, one-day-old broiler chickens were randomly assigned to one of four groups (six replicates each replicate has 12 chickens). A control basal diet (NC), basal diet plus antibiotic virginiamycin 15ppm (PC), basal diet plus phenylpyruvate 1 kg/t or 2 kg/t, respectively (LCP and HCP).3. Results showed that the birds in the PC group had higher ADFI during the first 21 d, and better FCR than the NC group. Feeding LCP and HCP improved broilers' FCR by 0.001 and 0.037% compared to the NC group respectively. The HCP-fed group has a higher all-eviscerated ratio than the NC group and less abdominal fat than the birds fed LCP. The birds fed HCP has increased villus length and crypt depth in the ileum compared to the NC group.4. The bursa index was lower in the HCP group whereas the thymus index was lower in LCP and PC groups. In contrast, birds fed HCP has lower pro-inflammatory cytokine IL-1, as well as lower TLR4. Phenylpyruvate improved number in the Selenomonadaceae, genus Megamonas bacteroides spp., which are known for their beneficial effects on the maintenance of the cell surface structure, regulating aromatic amino acids and Clostridia jejuni-suppressive treatment respectively.5. It was concluded that phenylpyruvate can be utilised in feed to improve growth performance and positively modulate gut microbiota. However, this was less efficient than antibiotics in improving growth performance, although more efficient in improving productive performance and gut morphology. Moreover, a high dose of phenylpyruvate is more effective than a low dose.

Developing Wound Dressings Using 2-deoxy-D-Ribose to Induce Angiogenesis as a Backdoor Route for Stimulating the Production of Vascular Endothelial Growth Factor

2-deoxy-D-Ribose (2dDR) was first identified in 1930 in the structure of DNA and discovered as a degradation product of it later when the enzyme thymidine phosphorylase breaks down thymidine into thymine. In 2017, our research group explored the development of wound dressings based on the delivery of this sugar to induce angiogenesis in chronic wounds. In this review, we will survey the small volume of conflicting literature on this and related sugars, some of which are reported to be anti-angiogenic. We review the evidence of 2dDR having the ability to stimulate a range of pro-angiogenic activities in vitro and in a chick pro-angiogenic bioassay and to stimulate new blood vessel formation and wound healing in normal and diabetic rat models. The biological actions of 2dDR were found to be 80 to 100% as effective as VEGF in addition to upregulating the production of VEGF. We then demonstrated the uptake and delivery of the sugar from a range of experimental and commercial dressings. In conclusion, its pro-angiogenic properties combined with its improved stability on storage compared to VEGF, its low cost, and ease of incorporation into a range of established wound dressings make 2dDR an attractive alternative to VEGF for wound dressing development.

A Structural and Functional Elucidation of the Rumen Microbiome Influenced by Various Diets and Microenvironments

The structure and function of the microbiome inhabiting the rumen are, amongst other factors, mainly shaped by the animal's feed intake. Describing the influence of different diets on the inherent community arrangement and associated metabolic activities of the most active ruminal fractions (bacteria and archaea) is of great interest for animal nutrition, biotechnology, and climatology. Samples were obtained from three fistulated Jersey cows rotationally fed with corn silage, grass silage or grass hay, each supplemented with a concentrate mixture. Samples were fractionated into ruminal fluid, particle-associated rumen liquid, and solid matter. DNA, proteins and metabolites were analyzed subsequently. DNA extracts were used for Illumina sequencing of the 16S rRNA gene and the metabolomes of rumen fluids were determined by 500 MHz-NMR spectroscopy. Tryptic peptides derived from protein extracts were measured by LC-ESI-MS/MS and spectra were processed by a two-step database search for quantitative metaproteome characterization. Data are available via ProteomeXchange with the identifier PXD006070. Protein- and DNA-based datasets revealed significant differences between sample fractions and diets and affirmed similar trends concerning shifts in phylogenetic composition. Ribosomal genes and proteins belonging to the phylum of Proteobacteria, particularly Succinivibrionaceae, exhibited a higher abundance in corn silage-based samples while fiber-degraders of the Lachnospiraceae family emerged in great quantities throughout the solid phase fractions. The analysis of 8163 quantified bacterial proteins revealed the presence of 166 carbohydrate active enzymes in varying abundance. Cellulosome affiliated proteins were less expressed in the grass silage, glycoside hydrolases appeared in slightest numbers in the corn silage. Most expressed glycoside hydrolases belonged to families 57 and 2. Enzymes analogous to ABC transporters for amino acids and monosaccharides were more abundant in the corn silage whereas oligosaccharide transporters showed a higher abundance in the fiber-rich diets. Proteins involved in carbon metabolism were detected in high numbers and identification of metabolites like short-chain fatty acids, methylamines and phenylpropionate by NMR enabled linkage between producers and products. This study forms a solid basis to retrieve deeper insight into the complex network of microbial adaptation in the rumen.

Redundancy, resilience, and host specificity of the ruminal microbiota: implications for engineering improved ruminal fermentations

The ruminal microbial community is remarkably diverse, containing 100s of different bacterial and archaeal species, plus many species of fungi and protozoa. Molecular studies have identified a “core microbiome” dominated by phyla Firmicutes and Bacteroidetes, but also containing many other taxa. The rumen provides an ideal laboratory for studies on microbial ecology and the demonstration of ecological principles. In particular, the microbial community demonstrates both redundancy (overlap of function among multiple species) and resilience (resistance to, and capacity to recover from, perturbation). These twin properties provide remarkable stability that maintains digestive function for the host across a range of feeding and management conditions, but they also provide a challenge to engineering the rumen for improved function (e.g., improved fiber utilization or decreased methane production). Direct ruminal dosing or feeding of probiotic strains often fails to establish the added strains, due to intensive competition and amensalism from the indigenous residents that are well-adapted to the historical conditions within each rumen. Known exceptions include introduced strains that can fill otherwise unoccupied niches, as in the case of specialist bacteria that degrade phytotoxins such as mimosine or fluoroacetate. An additional complicating factor in manipulating the ruminal fermentation is the individuality or host specificity of the microbiota, in which individual animals contain a particular community whose species composition is capable of reconstituting itself, even following a near-total exchange of ruminal contents from another herd mate maintained on the same diet. Elucidation of the interactions between the microbial community and the individual host that establish and maintain this specificity may provide insights into why individual hosts vary in production metrics (e.g., feed efficiency or milk fat synthesis), and how to improve herd performance.

Use of deoxyribose by intestinal and extraintestinal pathogenic Escherichia coli strains: a metabolic adaptation involved in competitiveness

We showed that the deoK operon, which confers the ability to use deoxyribose as a carbon source, is more common among pathogenic than commensal Escherichia coli strains. The expression of the deoK operon increases the competitiveness of clinical isolates, suggesting that this biochemical characteristic plays a role in host infectivity.

Regulation of expression of the 2-deoxy-D-ribose utilization regulon, deoQKPX, from Salmonella enterica serovar typhimurium

Salmonella enterica, in contrast to Escherichia coli K12, can use 2-deoxy-D-ribose as the sole carbon source. The genetic determinants for this capacity in S. enterica serovar Typhimurium include four genes, of which three, deoK, deoP, and deoX, constitute an operon. The fourth, deoQ, is transcribed in the opposite direction. The deoK gene encodes deoxyribokinase. In silico analyses indicated that deoP encodes a permease and deoQ encodes a regulatory protein of the deoR family. The deoX gene product showed no match to known proteins in the databases. Deletion analyses showed that both a functional deoP gene and a functional deoX gene were required for optimal utilization of deoxyribose. Using gene fusion technology, we observed that deoQ and the deoKPX operon were transcribed from divergent promoters located in the 324-bp intercistronic region between deoQ and deoK. The deoKPX promoter was 10-fold stronger than the deoQ promoter, and expression was negatively regulated by DeoQ as well as by DeoR, the repressor of the deoxynucleoside catabolism operon. Transcription of deoKPX but not of deoQ was regulated by catabolite repression. Primer extension analysis identified the transcriptional start points of both promoters and showed that induction by deoxyribose occurred at the level of transcription initiation. Gel retardation experiments with purified DeoQ illustrated that it binds independently to tandem operator sites within the deoQ and deoK promoter regions with K(d) values of 54 and 2.4 nM, respectively.

Do ruminal bacteria exchange genetic material?

This paper discusses the reasons and current evidence for gene transfer between ruminal bacteria and other bacteria in the environment, possible routes for genetic exchange, and candidate genes. Gene transfer between ruminal bacteria has been demonstrated in vitro; however, success has been only minimal in obtaining plasmids and other self-transmissible genetic material from ruminal bacteria. The application of molecular biology techniques with ruminal microorganisms should permit the opportunity for an in vivo assessment of gene transfer. Studies that could provide pertinent information for ruminal microbiologists and dairy nutritionists are outlined.

Ecology, metabolism, and genetics of ruminal selenomonads

Selenomonas ruminantium is one of the more prominent and functionally diverse bacteria present in the rumen and can survive under a wide range of nutritional fluctuations. Selenomonas is not a degrader of complex polysaccharides associated with dietary plant cell wall components, but is important in the utilization of soluble carbohydrates released from initial hydrolysis of these polymers by other ruminal bacteria. Selenomonads have multiple carbon flow routes for carbohydrate catabolism and ATP generation, and subspecies differ in their ability to use lactate. Some soluble carbohydrates (glucose, sucrose) appear to be transported via the phosphoenolpyruvate phosphotransferase system, while arabinose and xylose are transported by proton symport. High cell yields and the presence of electron transport components in Selenomonas strains has been documented repeatedly and this may partially account for the energy partitioning observed between energy consumed for growth and maintenance functions. Most strains can utilize ammonia, protein, and/or amino acids as a nitrogen source. Some strains can hydrolyze urea and/or reduce nitrate and use the ammonia for the biosynthesis of amino acids. Experimental evidence suggests that ammonia assimilatory enzymes in some strains may possess unique properties with respect to other presumably similar bacteria. Little is known about the genetics of ruminal selenomonads. Plasmid DNA has been isolated from some strains, but it is unknown what physiological functions may be encoded on these extrachromosomal elements. Due to the predominance of S. ruminantium in the rumen, it is an ideal candidate for genetic manipulation. Once the genetics of this bacterium are better understood, it may be possible to amplify its role in the rumen.