Alterations in the Colonic Microbiota of Pigs Associated with Feeding Distillers Dried Grains with Solubles

In an effort to reduce feed costs, many pork producers have increased their use of coproducts of biofuel production in commercial pig diets, including increased feeding of distiller’s dried grains with solubles (DDGS). The inclusion of DDGS increases the insoluble fiber content in the ration, which has the potential to impact the colonic microbiota considerably as the large intestine contains a dynamic microenvironment with tremendous interplay between microorganisms. Any alteration to the physical or chemical properties of the colonic contents has the potential to impact the resident bacterial population and potentially favor or inhibit the establishment of pathogenic species. In the present study, colonic contents collected at necropsy from pigs fed either 30% or no DDGS were analyzed to examine the relative abundance of bacterial taxa associated with feeding this ingredient. No difference in alpha diversity (richness) was detected between diet groups. However, the beta diversity was significantly different between groups with feeding of DDGS being associated with a decreased Firmicutes:Bacteriodetes ratio (P = .004) and a significantly lower abundance of Lactobacillus spp. (P = .016). Predictive functional profiling of the microbiota revealed more predicted genes associated with carbohydrate metabolism, protein digestion, and degradation of glycans in the microbiota of pigs fed DDGS. Taken together, these findings confirm that alterations in dietary insoluble fiber significantly alter the colonic microbial profile of pigs and suggest the resultant microbiome may predispose to the development of colitis.     

Effect of high fibre diets formulated with different fibrous ingredients on performance,nutrient digestibility and faecal microbiota of weaned piglets

The aim of the experiment on 180 weaned piglets (8.9 kg body weight) was to investigate the influence of high fibre diets formulated with different fibrous ingredients on performance, nutrient digestibility, diarrhoea incidence and numbers of faecal microbiota. The dietary treatments included a Control diet and five high fibre diets formulated with different fibre sources including wheat bran, soybean hulls, naked oat hulls, palm kernel expeller and bamboo fibre. The high fibre diets averaged 14.6% neutral detergent fibre with different non-starch polysaccharides (NSP) components and were fed ad libitum for 28 d. Faecal samples were collected during the last 3 d of the experiment and the apparent total tract digestibility of nutrients and fibre components were determined. Pigs fed the Control and wheat bran diets had a higher (p ≤ 0.05) average daily gain (ADG) than pigs fed the palm kernel expeller and bamboo meal diets. The reduced ADG for pigs appeared to be related to reductions in the digestibility of gross energy and dry matter, respectively. The feed-to-gain ratio was significantly higher (p ≤ 0.05) for pigs fed the fibre diets. The digestibility of NSP components was different among the treatments. The diarrhoea incidence was not affected by treatments. The abundance of faecal bifidobacteria was significantly higher (p ≤ 0.05) for pigs fed the wheat bran diet than for pigs fed the bamboo meal diet. It was concluded that the diets formulated with different fibre sources when fed to weaned piglets have different effects on pig performance, nutrient digestibility and numbers of faecal microbiota. The wheat bran diet rich in arabinoxylans enabled a better performance than the other tested diets with fibre addition.     

Comparative digestibility of energy and nutrients in diets fed to sows and growing pigs

The objective of this research was to compare values for digestible energy (DE) and metabolisable energy (ME) and apparent total tract digestibility (ATTD) of nutrients in 11 diets fed to both growing pigs and gestating sows. Three diets were based on corn, wheat or sorghum and eight diets were based on a combination of corn and soybean meal, canola meal, conventional distillers’ dried grains with solubles, low-fat distillers’ dried grains with solubles, corn germ meal, corn bran, wheat middlings or soybean hulls. A total of 88 gestating sows (252 ± 24.2 kg BW; parity two to six) and 88 growing barrows (40 ± 4.7 kg BW) were used and randomly allotted to the 11 diets with eight replicate sows or pigs per diet. Faecal and urine samples were collected for 4 d following a 19 d adaptation period. The DE, ME and ATTD of gross energy (GE), acid detergent fibre (ADF), neutral detergent fibre (NDF) and crude protein (CP) in the 11 diets were calculated. Gestating sows had greater (p < 0.05) ATTD of GE and CP and DE values for all diets compared with growing pigs. Gestating sows also had greater (p < 0.05) ME values than growing pigs for the three grain diets and the diets containing wheat middlings and soybean hulls. No differences were observed in ATTD of ADF and NDF between gestating sows and growing pigs for any of the diets, except that gestating sows had greater (p < 0.05) ATTD of NDF than growing pigs when they were fed the four protein diets. The ATTD of GE and CP and DE values in gestating sows may be predicted by using equations generated from the values of ATTD of GE and CP and DE values obtained in growing pigs. Results of this research indicate that ATTD values of CP and GE obtained in gestating sows are greater than the values obtained in growing pigs, but values for ATTD of ADF obtained in growing pigs are not different from values in gestating sows.     

Suitability of monotypic and mixed diets for Anopheles hermsi larval development

The developmental time and survival to eclosion of Anopheles hermsi Barr & Guptavanij fed monotypic and mixed diets of ten food types were examined in laboratory studies. Larvae fed monotypic diets containing animal detritus (freeze‐dried rotifers, freeze‐dried Daphnia pulicaria, and TetraMin® fish food flakes) and the mixotrophic protistan Cryptomonas ovata developed faster and survived better than larvae that were fed other monotypic diets. Survival to adulthood of larvae fed several concentrations of the diatom Planothidium (=Achnanthes) lanceolatum was poor (<13%) and larval development time was approximately twice that of larvae fed TetraMin® fish food flakes, the standard laboratory diet. Larvae fed monotypic diets containing prokaryotes (bacteria [Bacillus cereus] and cyanobacteria [Oscillatoria prolifera]) and brewer's yeast (Saccharomyces cerevisiae) failed to survive beyond the 1^st and 2^nd instar, respectively. Larvae fed only chlorophytes, single‐celled Chlamydomonas reinhardtii and filamentous Spirogyra communis, failed to complete larval development, regardless of the concentration tested. Cohorts fed a combination of food types (mixed diets) usually developed better than cohorts fed monotypic diets. Food types that failed to support complete development when fed alone often facilitated development to adulthood when fed in combination with food types containing >1% C₂₀ polyunsaturated fatty acids as total fat, but regardless of essential fatty acid content, algae that produced mucilage and filaments that sank out of the feeding zone were poor quality diets.     

Influence of dietary fibre on nutrient digestibility and energy utilisation in growing pigs fed diets varying in soluble and insoluble fibres from co-products

The co-products from the industry are used to reduce costs in pig diets. However, the co-products used in pig diets are limited because of a high fibre content which is not digested by endogenous enzymes and is resistant to degradation in the small and large intestines. The aim of this study was to investigate digestibility of nutrients and energy, and energy utilisation in pigs fed diets with various soluble and insoluble dietary fibre (DF) from co-products. The experiment was performed as a 4 × 4 Latin square design (four diets and four periods) using four growing pigs (66.2 ± 7.8 kg) surgically fitted with a T-cannula in the end of the small intestine. The pigs were fed four experimental diets: low-fibre control (LF), high-fibre control (HF), high-soluble fibre (HFS) and high-insoluble fibre (HFI) diets. The apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of ash, organic matter, CP, fat, carbohydrates, starch and non-starch polysaccharides (NSP) divided into cellulose and soluble and insoluble non-cellulosic polysaccharide residues were measured using chromic oxide as marker. The recovery of total solid materials, organic matter and total carbohydrates in ileal digesta in pigs fed the HF and HFS diets was higher than in pigs fed LF and HFI, whereas recovery of organic matter and total carbohydrates in faecal materials in the HFS diet was lowest (P < 0.05). AID of organic matter, total carbohydrates and starch was lowest for HFS diet (P < 0.05). ATTD of organic matter and CP was higher for LF diet compared with other diets (P < 0.05), whereas total NSP, cellulose and non-cellulosic polysaccharides residues were highest for HFS diet (P < 0.05). Lactic acid in ileal digesta was influenced by dietary composition (P < 0.05) whereas neither type nor level of DF affected short chain fatty acids. The digestible energy, metabolisable energy, net energy and retained energy intake were similar among diets without influence of DF inclusion (P > 0.05). The metabolisable energy:digestible energy ratio was lower when feeding the HFS diet because of a higher fermentative methane loss. Faecal nitrogen and carbon were positively correlated with DM intake and insoluble DF in the diets (P < 0.05), but nitrogen and carbon (% of intake) were similar among diets. The present findings suggest that high-DF co-products can be used as ingredients of pig diets when features of DF are considered.     

Increased amount of Bifidobacterium thermacidophilum and Megasphaera elsdenii in the colonic microbiota of pigs fed a swine dysentery preventive diet containing chicory roots and sweet lupine

AIMS: To investigate which specific bacterial species that were stimulated or inhibited in the proximal colon of pigs when a fructan-rich diet was compared with a diet that contained resistant carbohydrates. The study focussed especially on Bifidobacterial species by using a noncultureable approach. METHODS AND RESULTS: Terminal restriction fragment length polymorphism (T-RFLP) was used to describe differences in the total colonic microbiota as well as in the populations of Bifidobacterium spp. in pigs fed with a fructan-rich diet and a diet containing resistant carbohydrates. The fructan-rich diet has previously been shown to prevent swine dysentery caused by Brachyspira hyodysenteriae. The T-RFLP profiling, 16S rRNA gene cloning and in situ hybridization showed that the pigs fed with the fructan-rich diet had a higher proportion of Bifidobacterium thermacidophilum subsp. porcinum and Megasphaera elsdenii. CONCLUSIONS: These findings suggested that the bacterial fructan fermentation occurring in the porcine colon might be cross-feeding of lactate produced by B. thermacidophilum and used by M. elsdenii. SIGNIFICANCE AND IMPACT OF THE STUDY: B. thermacidophilum and M. elsdenii may be the course of the inhibition of the pathogenic bacteria Brach. hyodysenteriae in colon of pigs when they are fed fructan-rich diets.     

Alteration of the gastrointestinal microbiota of mice by edible blue-green algae

Aims:  To characterize the effect of edible blue-green algae (cyanobacteria) on the gastrointestinal microbiota of mice.
Methods and Results:  C57BL/6J mice were fed a diet supplemented with 0% or 5% dried Nostoc commune , Spirulina platensis or Afanizominon flos-aquae (w/w) for 4 weeks. Molecular fingerprinting of the colonic microbiota using denaturing gradient gel electrophoresis revealed that administration of N. commune induced major alterations in colonic microbiota composition, while administration of S. platensis or A. flos-aquae had a more subtle impact. Community profile analysis revealed that administration of N. commune did not reduce microbial diversity indices of the colonic microbiota. Despite its pronounced effects on the bacterial composition in the colon, total bacterial numbers in the gut of mice fed N. commune were not reduced as assessed by quantitative real-time PCR and bacteriological culture.
Conclusions:  The results presented here show that administration of blue-green algae, and especially N. commune , alters colonic microbiota composition in mice with limited effects on total bacterial numbers or microbial diversity.
Significance and Impact of the Study:  Blue-green algae are consumed in many countries as a source of nutrients and to promote health, and they are intensively studied for their pharmaceutical value. Given the importance of the gut microbiota for many host functions, the effects of blue-green algae on gut microbial ecology revealed during this study should be considered when using them as food supplements or when studying their pharmaceutical properties.     

Effects of Dietary Non-Digestible Oligosaccharides on Microbial Characteristics of Ileal Chyme and Faeces in Weaner Pigs

Fructooligosaccharides (FOS) and transgalactooligosaccharides (TOS), which are non-digestible oligosaccharides (NDO), were included at 10 and 40g/kg in an NDO-free control diet at the expense of purified cellulose. Each of the 5 diets was fed to 4 weaner pigs and microbial characteristics of their ileal chyme and faeces were assessed. The NDO-pigs had lower ileal pH than the control pigs. Dietary NDO did not affect the ileal volatile fatty acid concentration, though FOS-pigs had a higher concentration of lactic acid and relatively more iso-valeric acid and less acetic acid than TOS-pigs. The NDO-pigs had lower ileal aerobic bacterial counts than the control pigs, whilst the FOS-pigs had a larger ileal anaerobic bacterial counts than the TOS-pigs. The NDO-pigs had an higher faecal pH and their faecal volatile fatty acid pool contained relatively more iso-butyric acid and iso-valeric acid than the control pigs. The TOS-pigs tended to have higher faecal anaerobic bacterial counts and had a smaller concentration of faecal volatile fatty acid than the FOS-pigs. We concluded that whilst effects at the faecal level may have been partly due to a reduced intake of cellulose, dietary NDO can exert precaecal prebiotic effects in weaner pigs.     

Effects of fibre-degrading enzymes in combination with different fibre sources on ileal and total tract nutrient digestibility and fermentation products in pigs

ABSTRACT

The study was conducted to determine effects of a complex of fibre-degrading enzymes (xylanase, cellulase and β-glucanase) on nutrient digestibility, fibre fermentation and concentrations of short chain fatty acids (SCFA) at different parts of digestive tract in pigs fed different fibre-rich ingredients. A total of 36 barrows fitted with T-cannulas in the distal ileum (initial body weight of 41.1 ± 2.7 kg) were randomly allotted to six dietary treatments with three different high-fibre diets including maize bran (MB), sugar beet pulp (SBP) and soybean hulls (SH) with or without supplementation of fibre-degrading enzymes. Enzyme supplementation improved (p < 0.05) apparent ileal digestibility (AID) of dietary gross energy (GE), crude protein, dry matter (DM), organic matter (OM), total dietary fibre (TDF), neutral detergent fibre (NDF) and apparent total tract digestibility (ATTD) of dietary GE, DM, OM, TDF, insoluble dietary fibre (IDF) when pigs were fed MB, SBP or SH diets. When compared to the SBP and SH diets, the AID of GE, DM, ash, OM and NDF in diet MB was higher (p < 0.05), but the hindgut disappearance and ATTD of nutrients, except for ether extract and crude ash, were lower (p < 0.05). Enzyme supplementation increased acetate and total SCFA concentrations in ileal digesta and faeces of pigs. In conclusion, enzyme addition improved IDF fermentation and SCFA concentration in the whole intestine of pigs, and there was a large variation of digestibility of fibre components among MB, SH and SBP owing to their different fibre composition. Therefore, fibre-degrading enzymes should be applied to fibrous diets to improve efficient production of swine, especially considering low fibre digestibility of fibre-rich ingredients.     

The effects of inulin,dried Jerusalem artichoke tuber and a multispecies probiotic preparation on microbiota ecology and immune status of the large intestine in young pigs

The study aimed at determining the effect of two types of prebiotics and a multispecies probiotic on microbiota activity and composition, as well as mucosal immunity in the large intestine of young pigs. In total 48 piglets were divided into 6 groups (n = 8), which received from day 10 of life probiotic-unsupplemented (PU) or probiotic-supplemented (PS) diets. Probiotics were added at 0.5 g/kg diet and contained: Lactococcus lactis, Carnobacterium divergens, Lactobacillus casei, Lactobacillus plantarum and Saccharomyces cerevisiae. The PU and PS diets were formulated without prebiotic addition (control) or with addition of 2% of inulin from chicory root (IN) or 4% of dried Jerusalem artichoke tubers (DJA). After 40 days of feeding, digesta and tissue samples were taken from the caecum and three sections of the colon for analyses of microbiota activity and composition, secretory immunoglobulin A (sIgA) and intraepithelial lymphocytes (IEL). IN diets decreased the caecal digesta pH and β-glucosidase activity but increased propionic, valeric and total short chain fatty acid (SCFA) concentrations compared to control diets. Feeding DJA diets increased caecal valeric acid level, decreased the concentration of isoacids in the colon, reduced β-glucosidase and β-glucuronidase activity in the middle colon and increased Bifidobacterium spp. populations in the proximal and distal colon. PS diets increased the caecal acetic acid and total SCFA level, and Clostridium spp. populations in the distal colon. Neither probiotic nor prebiotics affected sIgA level or IEL number in the large intestine. In conclusion, DJA modified the microbiota ecology in the large intestine of young pigs to a greater extent than IN and the applied probiotic did not enhance effects of prebiotics.     

Changing Dietary Calcium-Phosphorus Level and Cereal Source Selectively Alters Abundance of Bacteria and Metabolites in the Upper Gastrointestinal Tracts of Weaned Pigs

Several dietary ingredients may affect the bacterial community structure and metabolism in the porcine gut and may therefore influence animals'' health and performance. This study investigated the effects of cereal source and calcium-phosphorus (CaP) level in the diet on bacterial microbiota and metabolites, nutrient intake, and gut environment in weaned pigs. Pigs (n = 8/treatment) were fed wheat-barley- or corn-based diets with an adequate or high CaP level for 14 days. Effects on microbiota in the stomach, ileum, and midcolon were assessed using quantitative PCR. Data showed that Enterobacteriaceae, Campylobacter spp., and Helicobacter spp., which all contain highly immune reactive lipopolysaccharide (LPS), were abundant at all gut sites. Diet effects on bacteria and metabolites were moderate and occurred mainly in the upper gut, whereas no effects on bacteria, fermentation products, and LPS could be observed in the colon. Differences in carbohydrate intake with corn versus wheat-barley diets selectively stimulated Bifidobacterium in the stomach and ileum. There was a growth advantage for a few bacterial groups in the stomach and ileum of pigs fed the high versus adequate CaP level (i.e., gastric Enterobacteriaceae and ileal Enterococcus, Bacteroides-Prevotella-Porphyromonas, and Campylobacter). Interestingly, gastrointestinal pH was not affected by dietary CaP level. The present findings demonstrate the stability of the bacterial community and gut environment toward dietary changes even in young pigs. The results on stimulation of gastric and ileal Bifidobacterium by corn diets may be employed in nutritional strategies to support gut health after weaning.     

Effects of insoluble dietary fibre differing in lignin on performance, gut microbiology, and digestibility in weanling piglets

The study aimed to investigate the effects of insoluble dietary fibre differing in lignin content on performance and parameters of gut microbiology in 48 weanling piglets (8.5 kg mean body weight) fed common diets ad libitum. Fibre sources tested were wheat bran (low lignin) and pollen from Chinese Masson pine (Pinus massoniana) as model of fibre rich in lignin, added to diets as follows: no addition (control), 3.0% wheat bran, 1.27% pine pollen and 2.55% pine pollen. In colonic chyme, bacterial colony counts remained unaffected by treatment, but ammonia contents were reduced by fibre additions (up to -38%). The effects on ammonia were best explained by added cellulose and lignin. Fibre additions reduced apparent (faecal) digestibility of dry matter (DM) and crude protein (CP) up to -3.5 and -4.3% units with cellulose and lignin being the major determinants for changes in CP digestibility.     

The intestinal microbiota of piglets fed with wheat bran variants as characterised by 16S rRNA next-generation amplicon sequencing

The intestinal microbiota of piglets fed with a Control diet low in dietary fibre and modified wheat bran variants as an additional source of insoluble dietary fibre was characterised. In this context, variances in the microbiota of three different gut segments were assessed. Wheat bran was either included in its native form or modified by fermentation and extrusion before added at 150 g/kg to a basal diet for 48 piglets (12 animals per treatment). Total DNA was extracted from digesta samples from the jejunum, the end of the ileum and the colon ascendens. Samples were prepared accordingly for subsequent sequencing with the Illumina MiSeq. The obtained results revealed distinct location-specific differences in microbial composition. While Firmicutes were most predominant in all three gut segments, Bacteroidetes were additionally found in the colon at high abundance. The parameters of alpha and beta diversity analysis showed significant differences (p < 0.01) between the colon and the other two gut segments. Specialised bacterial groups like Prevotella and Ruminococcaceae were among the most predominant ones found in the colon, as they possess cellulolytic properties to degrade (at least partially) non-starch polysaccharides, while their abundance was negligible in the jejunum and the ileum. Conversely, the genera Lactobacillus, Bifidobacterium and Veillonella, for example, were among the most predominant groups in the jejunum and ileum, while in the colon they were hardly found. Although statistical taxonomical evaluation, following p-value correction, did not reveal pronounced differences in abundance related to bran modification, alpha and beta diversity analysis showed an influence regarding the various feeding strategies applied. Based on these findings, a more in-depth view on intestinal microbial composition within the gastrointestinal tract of young pigs fed with low- and high-fibre diets was generated.     

A comparison between meals prepared from the seeds of different varieties of lupin as protein supplements to barley-based diets for growing pigs

Four experiments were conducted in order to examine the growth and voluntary feed consumption of young growing pigs fed on barley-based diets containing as the sole protein supplement lupin-seed meal (LSM) from either Lupinus angustifolius cv. Uniwhite (UW), Uniharvest (UH) or L. albus cv. Neuland (NL).Under the restricted feeding regimen of the first experiment pigs receiving diets containing either 31% or 43% of either UW or UH grew at similar rates and with similar efficiency of feed utilisation from 27.5 to 85 kg live weight. By contrast, all pigs fed on diets containing these same proportions of NL refused such large amounts of feed immediately after the diets were offered that their growth halted.In the second and third experiments the voluntary feed consumption of pigs weighing 18 to 34 kg and receiving diets containing 37 to 43% of any of three distinct lines of NL was significantly less than those of pigs receiving UW diets, to the extent in some cases that body-weight loss occurred.In the fourth experiment the growth and voluntary feed intakes of 20 to 30 kg pigs fed on a control diet containing a mixture of fishmeal and dried blood as the protein supplement were greater than those of pigs fed a UW diet, which in turn were greater than those of pigs receiving NL as the source of supplementary protein. Reduction of the alkaloid content of NL by ethanol extraction resulted in a recovery of growth and feed intake to levels similar to those supported by the UW diet.     

Metabolism of Klebsiella pneumoniae freeze‐dried cultures for the design of BOD bioassays

Aims: The survival rate of freeze‐dried cultures is not enough information for technological applications of micro‐organisms. There could be serious metabolic/structural damage in the survivors, leading to a delay time that can jeopardize the design of a rapid biochemical oxygen demand (BOD) metabolic‐based bioassay. Therefore, we will study the metabolic activity (as ferricyanide reduction activity) and the survival rate (as colony‐forming units, CFU) of different Klebsiella pneumoniae freeze‐dried cultures looking for stable metabolic conditions after 35 days of storage. Method and Results: Here, we tried several simple freeze‐drying processes of Kl. pneumoniae. Electrochemical measurements of ferrocyanide and survival rates obtained with the different freeze‐dried cultures were used to choose the best freeze‐drying process that leads to a rapid metabolic‐based bioassay. Conclusions: The use of milk plus monosodium glutamate was the best choice to obtain a Kl. pneumoniae freeze‐dried culture with metabolic stable conditions after storage at ?20°C without the need of vacuum storage and ready to use after 20 min of rehydration. We also demonstrate that the viability and the metabolic activity are not always directly correlated. Significance and Impact of the Study: This study shows that the use of this Kl. pneumoniae freeze‐dried culture is appropriate for the design of a rapid BOD bioassay.     

Adaptation of faecal microbiota in sows after diet changes and consequences for in vitro fermentation capacity

In vitro gas production studies are routinely used to assess the metabolic capacity of intestinal microbiota to ferment dietary fibre sources. The faecal inocula used during the in vitro gas production procedure are most often obtained from animals adapted to a certain diet. The present study was designed to assess whether 19 days of adaptation to a diet are sufficient for faecal inocula of pigs to reach a stable microbial composition and activity as determined by in vitro gas production. Eighteen multiparous sows were allotted to one of two treatments for three weeks: a diet high in fibre (H) or a diet low in fibre (L). After this 3-week period, the H group was transferred to the low fibre diet (HL-treatment) while the L group was transferred to the diet high in fibre (LH-treatment). Faecal samples were collected from each sow at 1, 4, 7, 10, 13, 16 and 19 days after the diet change and prepared as inoculum used for incubation with three contrasting fermentable substrates: oligofructose, soya pectin and cellulose. In addition, inocula were characterised using a phylogenetic microarray targeting the pig gastrointestinal tract microbiota. Time after diet change had an effect (P<0.05) on total gas production for the medium–fast fermentable substrates; soya pectin and oligofructose. For the more slowly fermentable cellulose, all measured fermentation parameters were consistently higher (P<0.05) for animals in the HL-treatment. Diet changes led to significant changes in relative abundance of specific bacteria, especially for members of the Bacteroidetes and Bacilli, which, respectively, increased or decreased for the LH-treatment, while changes were opposite for the HL-treatment. Changing the diet of sows led to changes in fermentation activity of the faecal microbiota and in composition of the microbiota over time. Adaptation of the microbiota as assessed by gas production occurred faster for LH-animals for fast fermentable substrates compared with HL-animals. Overall, adaptation of the large intestinal microbiota of sows as a result of ingestion of low and high fibre diets seems to take longer than 19 days, especially for the ability to ferment slowly fermentable substrates.     

The hindgut lumen prokaryotic microbiota of the termite Reticulitermes flavipes and its responses to dietary lignocellulose composition

Reticulitermes flavipes (Isoptera: Rhinotermitidae) is a highly eusocial insect that thrives on recalcitrant lignocellulosic diets through nutritional symbioses with gut‐dwelling prokaryotes and eukaryotes. In the R. flavipes hindgut, there are up to 12 eukaryotic protozoan symbionts; the number of prokaryotic symbionts has been estimated in the hundreds. Despite its biological relevance, this diverse community, to date, has been investigated only by culture‐ and cloning‐dependent methods. Moreover, it is unclear how termite gut microbiomes respond to diet changes and what roles they play in lignocellulose digestion. This study utilized high‐throughput 454 pyrosequencing of 16S V5‐V6 amplicons to sample the hindgut lumen prokaryotic microbiota of R. flavipes and to examine compositional changes in response to lignin‐rich and lignin‐poor cellulose diets after a 7‐day feeding period. Of the ~475 000 high‐quality reads that were obtained, 99.9% were annotated as bacteria and 0.11% as archaea. Major bacterial phyla included Spirochaetes (24.9%), Elusimicrobia (19.8%), Firmicutes (17.8%), Bacteroidetes (14.1%), Proteobacteria (11.4%), Fibrobacteres (5.8%), Verrucomicrobia (2.0%), Actinobacteria (1.4%) and Tenericutes (1.3%). The R. flavipes hindgut lumen prokaryotic microbiota was found to contain over 4761 species‐level phylotypes. However, diet‐dependent shifts were not statistically significant or uniform across colonies, suggesting significant environmental and/or host genetic impacts on colony‐level microbiome composition. These results provide insights into termite gut microbiome diversity and suggest that (i) the prokaryotic gut microbiota is much more complex than previously estimated, and (ii) environment, founding reproductive pair effects and/or host genetics influence microbiome composition.     

江山乌猪肠道黏膜菌群组成及其功能的性别差异

肠道黏膜微生物在调控宿主生理功能方面发挥重要作用,其结构组成受到多种因素影响。性别被认为是塑造肠道微生物的因素之一。然而,性别对肠道黏膜菌群的差异影响还不清楚。【目的】以江山乌猪为研究对象,探究性别差异对其肠道黏膜微生物组成及功能的影响。【方法】选取性成熟的雌性和雄性江山乌猪各8头,利用16S rRNA基因高通量测序技术分析回肠和结肠黏膜菌群。【结果】在回肠黏膜中,雄性江山乌猪菌群的Chao1指数和Shannon指数显著高于雌性(P<0.05),在结肠黏膜中,不同性别江山乌猪菌群Chao1指数和Shannon指数无显著差异(P>0.05)。菌群差异分析显示,回肠黏膜中,沙雷氏菌属(Serratia)和埃希氏志贺菌属(Escherichia_Shigella)在雌性组中的相对丰度显著高于雄性组(P<0.05),雄性组中Oscillospiraceae UCG-005、拟普雷沃氏菌属(Alloprevotella)、布劳特氏菌属(Blautia)和Prevotellaceae_NK3B31_group相对丰度显著高于雌性组(P<0.05);结肠黏膜中,雌性组中unclassified_Muribaculaceae、Rikenellaceae_RC9_gut_group和Prevotellaceae UCG-003相对丰度显著高于雄性组(P<0.05),Oscillospiraceae UCG-005、Lachnospiraceae_NK4A136_group和unclassified_Lachnospiraceae在雄性组中相对丰度更高(P<0.05)。功能预测发现,雄性乌猪回肠黏膜菌群显著富集了氨基酸代谢、碳水化合物代谢和能量代谢等功能途径(P<0.05);结肠黏膜菌群主要富集了膜转运相关的ABC转运蛋白和信号转导相关的双组分系统等功能途径(P<0.05)。【结论】不同性别江山乌猪肠黏膜菌群结构及功能具有明显差异。这些结果揭示了不同性别江山乌猪肠道黏膜菌群的差异特征,为了解和挖掘我国地方畜禽品种肠道微生物资源提供部分参考。     

Influence of different fibre sources on digestibility and nitrogen and energy balances in growing pigs

Abstract

The present study was undertaken to investigate how three different fibre sources, sugar beet pulp, soya bean hulls and pectin residue, constituting 15% of diets for growing pigs, influenced daily body gain, feed conversion, apparent faecal digestibility and nitrogen and energy balances. Eight castrated crossbreed pigs (30 – 80 kg live weight) were used in a replicated 4 × 4 Latin-square design with one control diet and three fibre containing diets. Daily body weight gain and feed conversion were not affected by the dietary treatments. The apparent faecal digestibility of organic matter (OM) and energy were significantly lower for the fibre diets (OM: 0.81 – 0.85; energy: 0.78 – 0.83) compared to the control diet (OM: 0.88; energy: 0.86). The apparent faecal digestibility of crude protein (CP) was lower for the fibre diets (0.71 – 0.78) compared to the control diet (0.83), although it was only significantly lower for the sugar beet pulp and pectin residue diets. The pectin residue diet, which contained the highest amount of dietary fibre, lignin and insoluble non-starch polysaccharides, had the lowest digestibility of OM, CP and energy. There was a tendency (p = 0.07) for a diet effect on retained nitrogen in proportion to digested nitrogen, where the sugar beet pulp and pectin residue diets had numerically the highest values. Heat production and retained energy in proportion to metabolizable energy intake were not affected by fibre inclusion. It was concluded that the inclusion of sugar beet pulp, soya bean hulls and pectin residue in diets for growing pigs decreased the apparent faecal digestibility and in the diets with sugar beet pulp and pectin residue higher utilization of digested nitrogen for retention compensated for the lower amount of digested nitrogen.