The cultivation of cellulolytic protozoa isolated from the rumen

Rumen fermentation and microbiota in Shami goats fed on condensed tannins or herbal mixture

BACKGROUND

Phytochemical compounds can modify the rumen microbiome and improve rumen fermentation. This study evaluated the impact of supplementation with tannin and an herbal mixture containing ginger (Zingiber officinale), garlic (Allium sativum), Artemisia (Artemisia vulgaris), and turmeric (Curcuma longa) on the rumen fermentation and microbiota, and histology of rumen tissue of goats. Eighteen Shami male goats were divided into three groups (n = 6): non-supplemented animals fed the basal diet (C, control); animals fed basal diet and supplemented with condensed tannin (T); and animals fed basal diet and supplemented with herbal mixture (HM). Each animal received a basal diet composed of Alfalfa hay and a concentrate feed mixture.

RESULTS

Group HM revealed higher (P < 0.05) rumen pH, total volatile fatty acids (VFA), acetic, propionic, isobutyric, butyric, isovaleric, and valeric. Principal Co-ordinate analysis (PCoA) showed that rumen microbial communities in the control group and supplemented groups were distinct. The supplementation increased (P < 0.05) the relative abundances of phylum Bacteroidota and Proteobacteria and declined (P < 0.05) Firmicutes and Fibrobacterota. Additionally, the dominant genus Prevotella and Rikenellaceae RC9 gut group were increased (P < 0.05) and the family Ruminococcaceae was declined (P < 0.05) due to the supplementation. The supplementation decreased (P < 0.05) the archaeal genus Methanobrevibacter and increased (P < 0.05) Candidatus Methanomethylophilus. Tannin supplementation in T group shortened the rumen papillae.

CONCLUSIONS

The results revealed that the herbal mixture might be used to alter the rumen microbiota to improve rumen fermentation.

Comparative analysis of the metabolically active microbial communities in the rumen of dromedary camels under different feeding systems using total rRNA sequencing

Breakdown of plant biomass in rumen depends on interactions between bacteria, archaea, fungi, and protozoa; however, the majority of studies of the microbiome of ruminants, including the few studies of the rumen of camels, only studied one of these microbial groups. In this study, we applied total rRNA sequencing to identify active microbial communities in 22 solid and liquid rumen samples from 11 camels. These camels were reared at three stations that use different feeding systems: clover, hay and wheat straw (G1), fresh clover (G2), and wheat straw (G3). Bacteria dominated the libraries of sequence reads generated from all rumen samples, followed by protozoa, archaea, and fungi respectively. Firmicutes, Thermoplasmatales, Diplodinium, and Neocallimastix dominated bacterial, archaeal, protozoal and fungal communities, respectively in all samples. Libraries generated from camels reared at facility G2, where they were fed fresh clover, showed the highest alpha diversity. Principal co-ordinate analysis and linear discriminate analysis showed clusters associated with facility/feed and the relative abundance of microbes varied between liquid and solid fractions. This provides preliminary evidence that bacteria dominate the microbial communities of the camel rumen and these communities differ significantly between populations of domesticated camels.

Dynamic role of single-celled fungi in ruminal microbial ecology and activities

In ruminants, high fermentation capacity is necessary to develop more efficient ruminant production systems. Greater level of production depends on the ability of the microbial ecosystem to convert organic matter into precursors of milk and meat. This has led to increased interest by animal nutritionists, biochemists and microbiologists in evaluating different strategies to manipulate the rumen biota to improve animal performance, production efficiency and animal health. One of such strategies is the use of natural feed additives such as single-celled fungi yeast. The main objectives of using yeasts as natural additives in ruminant diets include; (i) to prevent rumen microflora disorders, (ii) to improve and sustain higher production of milk and meat, (iii) to reduce rumen acidosis and bloat which adversely affect animal health and performance, (iv) to decrease the risk of ruminant-associated human pathogens and (v) to reduce the excretion of nitrogenous-based compounds, carbon dioxide and methane. Yeast, a natural feed additive, has the potential to enhance feed degradation by increasing the concentration of volatile fatty acids during fermentation processes. In addition, microbial growth in the rumen is enhanced in the presence of yeast leading to the delivery of a greater amount of microbial protein to the duodenum and high nitrogen retention. Single-celled fungi yeast has demonstrated its ability to increase fibre digestibility and lower faecal output of organic matter due to improved digestion of organic matter, which subsequently improves animal productivity. Yeast also has the ability to alter the fermentation process in the rumen in a way that reduces methane formation. Furthermore, yeast inclusion in ruminant diets has been reported to decrease toxins absorption such as mycotoxins and promote epithelial cell integrity. This review article provides information on the impact of single-celled fungi yeast as a feed supplement on ruminal microbiota and its function to improve the health and productive longevity of ruminants.

Potential for improving fiber digestion in the rumen of cattle (Bos taurus) through microbial inoculation from bison (Bison bison): In situ fiber degradation

The objective of this experiment was to determine if partial replacement of cattle rumen contents with those from bison would increase in situ ruminal fiber degradation of various forages. The second objective was to examine individual variation among cattle in their ability to degrade forage and their responses to inoculation. In situ degradation of barley straw, canola straw, alfalfa hay, and timothy hay was measured in 16 ruminally cannulated heifers fed a barley straw-based diet before and after inoculation with combined rumen contents from 32 bison (performed twice, 14 d apart). Each feed was incubated in the rumen of each heifer for 0, 4, 8, 12, 24, 48, 96, and 120 h, and the degradation parameters were determined as washout fraction (), potentially degradable fraction (), rate of digestion of fraction (), and total potentially degradable fraction (). The of barley straw decreased ( = 0.04) after inoculation, whereas fraction of NDF increased ( = 0.03) and fraction of NDF and ADF decreased ( ≤ 0.02) by inoculation. In contrast, of alfalfa hay NDF and ADF decreased ( = 0.002) after inoculation, but fraction of NDF and ADF ( ≤ 0.02) increased. There were no major effects ( > 0.06) of inoculation on the fiber degradation of timothy hay or canola straw. The differential response between barley straw and alfalfa hay may have occurred because the cattle were previously adapted to a barley straw diet, whereas the bison were fed barley silage and oats. Some animals consistently ranked higher or lower for or across at least 3 of the 4 feeds incubated, but the rankings changed after inoculation. In conclusion, inoculation of cattle with bison rumen contents failed to improve degradation of fiber from barley straw, canola straw, or timothy hay in cattle well adapted to a barley straw diet, although there were small improvements in the extent of degradation of fiber from alfalfa hay. Cattle varied both in their ability to degrade various forages and in their responses to inoculation with bison rumen contents.

Design and validation of four new primers for next-generation sequencing to target the 18S rRNA genes of gastrointestinal ciliate protozoa

Four new primers and one published primer were used to PCR amplify hypervariable regions within the protozoal 18S rRNA gene to determine which primer pair provided the best identification and statistical analysis. PCR amplicons of 394 to 498 bases were generated from three primer sets, sequenced using Roche 454 pyrosequencing with Titanium, and analyzed using the BLAST database (NCBI) and MOTHUR version 1.29. The protozoal diversity of rumen contents from moose in Alaska was assessed. In the present study, primer set 1, P-SSU-316F and GIC758R (amplicon of 482 bases), gave the best representation of diversity using BLAST classification, and the set amplified Entodinium simplex and Ostracodinium spp., which were not amplified by the other two primer sets. Primer set 2, GIC1080F and GIC1578R (amplicon of 498 bases), had similar BLAST results and a slightly higher percentage of sequences that were identified with a higher sequence identity. Primer sets 1 and 2 are recommended for use in ruminants. However, primer set 1 may be inadequate to determine protozoal diversity in nonruminants. The amplicons created by primer set 1 were indistinguishable for certain species within the genera Bandia, Blepharocorys, Polycosta, and Tetratoxum and between Hemiprorodon gymnoprosthium and Prorodonopsis coli, none of which are normally found in the rumen.

The rate of uptake and metabolism of starch grains and cellulose particles by Entodinium species, Eudiplodinium maggii, some other entodiniomorphid protozoa and natural protozoal populations taken from the ovine rumen

The rates of engulfment and breakdown of starch grains and cellulose particles and of the rate of synthesis of amylopectin from cellulose by individual species of entodiniomorphid protozoa (grown in vivo and in vitro) and incubated anaerobically in vitro were studied. Rates of starch uptake varied from 2.3 to 770 micrograms/mg protozoal protein/min; the lowest was found with Diploplastron affine and the highest with Entodinium spp. on initial incubation with starch grains. The rate of starch breakdown varied from 0.49 to 8.6 micrograms/mg protein/min; the rate was dependent on the initial starch concentration inside the protozoa. Eudiplodinium maggii engulfed cellulose particles more rapidly (2-7 times) than rice starch grains and digested the cellulose at rates of 10 to 16.5 micrograms/mg protein/min. In a mixture of starch grains and cellulose particles, it engulfed the latter at 1.35 to 25 times the rate of the former. Eudiplodinium maggii and Epidinium caudatum, but not Entodinium spp. or Dip. affine, synthesized an amylopectin-like material from cellulose at rates of 0.4 to 4.75 micrograms/mg protein/min. If these reactions occur in the rumen in vivo, up to 9 g of amylopectin could be synthesized from cellulose each day by the entodiniomorphid protozoa.

Association of rumen ciliate populations with plant particles in vitro

Seven known species of rumen ciliates and mixedEntodinium spp. showed association with plant particles in rumen fluid in vitro. Association was greater with fresh particles than with hay, and substantially decreased when the water-soluble components of the particles were removed, suggesting that the water-soluble components may be responsible for the association. The association was rapid and maximal between 5 and 35 min (depending on the ciliate species) after exposure to the particles, and involved major transfers of ciliate populations and biomass from the liquid phase to the solid phase of the system. The most rapid and largest population transfers to the particles from the rumen fluid were shown by the holotrich ciliates, where transfers of up to 97% of the population were recorded. Association with plant particles by all species examined occurred within the pH range 5.5-7.5, and decreased with time when the particles were incubated in rumen contents in vivo. The ciliate biomass transferring from the liquid to the solid phase varied with the composition of the ciliate population.

The uptake and utilization of Entodinium caudatum, bacteria, free amino acids and glucose by the rumen ciliate Entodinium bursa

Washed suspensions of Entodinium bursa were incubated anaerobically with Entodinium caudatum, ten species of bacteria and a yeast. The rate of uptake and digestion of these micro-organisms was investigated. Protozoa grown in vivo did not engulf Proteus mirabilis or Klebsiella aerogenes but rapidly took up Bacillus megaterium. Selenomonas ruminantium, Torulopsis glabrata and Streptococcus bovis, although only the last was digested with release of soluble material into the medium. Protozoa grown in vitro engulfed each of the bacteria tested, taking up Megasphaera elsdenii and Proteus mirabilis most rapidly. Individual bacterial species and mixed rumen bacteria were engulfed more rapidly (up to 20 times) by protozoa grown in vivo than those grown in vitro, although the latter digested over 80% of the B. megaterium, Escherichia coli and P. mirabilis taken up. Labelled Ent. caudatum was extensively digested after engulfment by Ent. bursa. Some of the digestion products were released into the medium but individual amino acids were transferred as such from Ent. caudatum protein to Ent. bursa protein. Engulfed bacteria and polysaccharide granules were transferred intact from one protozoon to the other. Free amino acids were also taken up intact from the medium into protozoal protein but there was little biosynthesis of amino acids from glucose. When available for engulfment Ent. caudatum was quantitatively a much more valuable source of amino acids for protein synthesis by Ent. bursa than free amino acids or bacteria.

The effect of free and protected oils on the digestion of dietary carbohydrates between the mouth and duodenum of sheep

Sheep fitted with rumen and re-entrant duodenal cannulas were given diets of approximately 200 g hay and 400 g concentrate mixture alone, or supplemented daily with 40 g linseed or coconut oils free or protected with formaldehyde-casein in a 5 x 5 Latin-square arrangement. Chromic oxide paper was given as a marker at feeding time and passage to the duodenum of neutral-detergent fibre (NDF) and different sugars were estimated from the values for constituent:marker at the duodenum. Contributions of microbial carbohydrates to these flows were estimated from amounts of RNA present. The carbohydrate composition of mixed rumen bacteria from sheep rumen digesta were similar regardless of diet. Of the sugars entering the duodenum all the rhamnose and ribose and 0.51, 0.24 and 0.35 of the mannose, galactose and starch-glucose respectively, were contributed by the microbes. Virtually all the arabinose, xylose and cellulose-glucose were contributed by the diet. For sheep receiving the basal ration, coefficients of digestibility between mouth and duodenum, corrected where necessary for microbial contribution, were 0.95, 0.66, 0.67, 0.62, 0.45 and 0.51 for starch-glucose, mannose, arabinose, galactose, xylose and cellulose-glucose respectively. Corresponding values when free-oil-supplemented diets were given were 0.95, 0.55, 0.38, 0.55, 0.01 and -0.02 respectively. Values for diets supplemented with linseed oil or coconut oil did not differ significantly. Addition of protected oils to the basal feed also resulted in depressed digestibilities of dietary structural sugars but to a far lesser extent than those observed with the free oils. Apparent digestibility of NDF was altered in the same direction as those of the main structural sugars, averaging 0.50, 0.17 and 0.29 in animals receiving the basal, free-oil-supplemented or protected-oil-supplemented diets respectively. The reasons for the difference between NDF and discrete carbohydrate analytical totals are discussed.

Cecal microflora of turkeys fed low or high fiber diets: enumeration, identification, and determination of cellulolytic activity

Examination of cecal contents or bacterial cultures thereof from turkeys fed either a high fiber (HF) or low fiber (LF) ration indicated that direct microscopic counts of microbes were significantly higher in HF-fed than in LF-fed birds. There was no significant difference in mean colony counts between the two groups of turkeys. In both LF and HF-fed birds, 77% of the microbes were Gram-positive rods, 14% Gram-negative rods, and 9% Gram-positive cocci. The predominant microorganism was Eubacterium, but Lactobacillus, Peptostreptococcus, Escherichia coli, Propionibacterium, and Bacteriodes were also isolated. Percentages of Peptostreptococcus were significantly greater in HF-fed turkeys and of E. coli were significantly greater in LF-fed turkeys. Yeasts were routinely found in both LF and HF-fed birds, but protozoa were not isolated. Turkeys fed the HF diet harbored significantly higher numbers of facultative microorganisms than did LF-fed birds. In pure cultures from turkeys preconditioned to a HF diet, there was a nonsignificant trend toward greater cellulolysis than in pure cultures from LF-fed turkeys. In contrast, cellulolysis by mixed cultures from HF-fed birds was significantly greater than that in mixed cultures from LF-fed turkeys.