Evaluation of the prebiotic potential of arabinoxylans extracted from wheat distillers’ dried grains with solubles (DDGS) and in-process samples

Applied Microbiology and Biotechnology - Distillers’ dried grains with solubles (DDGS) is a low-value agro-industrial by-product, rich in arabinoxylans (AX), which is produced by commercial...     

Amino acid digestibility in corn distillers’ dried grains with solubles in pigs at different dietary levels of casein and test ingredient

Digestibility of amino acids (AA) in feed ingredients for pigs has been generally determined by feeding experimental diets containing test feedstuffs as a sole source of N, which may lead to the deficiency or imbalance of AA and hinder an accurate determination of digestibility values. Therefore, the addition of casein in experimental diets may ameliorate the potential negative effects of deficiency or imbalance of AA. In addition, the concentration of test feedstuffs in experimental diets may affect the digestibility of AA in test feedstuffs. Two experiments were conducted with corn distillers’ dried grains with solubles (DDGS) as the test feedstuff to determine the effects of increasing concentrations of casein in experimental diets on standardized ileal digestibility (SID) of AA in DDGS (experiment 1) and to investigate the effects of two concentrations of DDGS in experimental diets with or without the addition of casein on SID of AA in DDGS (experiment 2). In experiment 1, 20 barrows (initial BW = 45.3 ± 1.80 kg) surgically fitted with T-cannulas at the distal ileum were allocated to a quadruplicate 5 × 2 incomplete Latin square design with five diets and two periods. Four isonitrogenous diets containing increasing concentrations of casein from 0 to 165 g/kg with decreasing concentrations of DDGS from 466.8 to 0 g/kg and a N-free diet were prepared. The SID of AA, except for arginine, cysteine, and glycine, in DDGS linearly decreased (P < 0.05) with increasing concentrations of casein in experimental diets. Quadratic response (P = 0.023) was observed in the SID of lysine in DDGS when the concentration of casein in experimental diets increased. In experiment 2, the same 20 barrows (initial BW = 52.8 ± 2.99 kg) and experimental design as experiment 1 were used with different diets, which were prepared as a 2 × 2 factorial arrangement with the concentration of DDGS at 466.8 or 155.6 g/kg and that of casein at 0 or 110 g/kg. Regardless of the addition of casein, pigs fed experimental diets containing 466.8 g/kg DDGS had greater (P < 0.01) SID of indispensable AA, except for tryptophan, in DDGS than those fed diets containing 155.6 g/kg DDGS. In conclusion, the addition of casein in experimental diets did not affect the SID of AA in DDGS, whereas the SID of AA in DDGS decreased as the concentration of DDGS in diets decreased.     

Variations in chemical composition and in vitro and in situ ruminal degradation characteristics of dried distillers’ grains with solubles from European ethanol plants

The objective of this study was to characterise variations in the composition and nutritive value of dried distillers’ grains with solubles (DDGS) for ruminants, and to estimate the undegradable crude protein (UDP) in DDGS. Thirteen samples originating from wheat, corn, barley and blends of different substrates were studied. The rumen degradation of crude protein (CP) was determined using the nylon bag technique. Samples were incubated for 0, 1, 2, 4, 8, 16, 32 and 72 h, and in situ degradation kinetics were determined. The UDP was estimated using a passage rate of 8%/h. In vitro gas production was measured to estimate the metabolisable energy (ME), net energy for lactation (NE_L) and in vitro digestibility of organic matter (IVDOM). Chemical profiles varied among samples [in g/kg dry matter (DM) ± standard deviation]; the values were 310 ± 33 CP, 86 ± 37 ether extract, 89 ± 18 crude fibre, 408 ± 39 neutral detergent fibre, 151 ± 39 acid detergent fibre and 62 ± 31 acid detergent lignin, as well as in protein fractions according to the Cornell Net Carbohydrate and Protein System [in g/kg CP]; the values were for fractions A, 161 ± 82; B1, 24 ± 11; B2, 404 ± 105; B3, 242 ± 61; and C, 170 ± 87. The ME, NE_L [MJ/kg DM] and IVDOM [%] also varied among samples: 12.1 ± 0.59, 7.3 ± 0.39 and 72.5 ± 4.30, respectively. The in situ rapidly degradable CP fraction (a) varied from 10.2% to 30.6%, and the potentially degradable fraction (b) averaged to 66.8%. The UDP varied from 8.6% to 62.6% of CP. The present study suggests significant variations in composition and nutritive value among different sources of DDGS. The UDP could be predicted on the basis of analysed CP fractions, but the accuracy of UDP prediction improved upon the inclusion of neutral-detergent insoluble nitrogen, explaining 94% of the variation in the UDP values. We conclude that chemical protein fractions may be used to predict the UDP values of DDGS and that the variability in the protein fractions of DDGS should be considered when formulating diets for dairy cows.     

Effect of dried corn distillers’ grains with solubles and soybean meal supplements on physiological indicators and reproductive performance of ewes

This study aimed to evaluate the effects of adding dried distillers’ grains with solubles (DDGS) to the nutritional regimens of ewes at different time periods on reproductive traits, serum hormones and serum metabolites. In Experiment 1, 100 ewes were divided into 4 groups (n = 25) according to diet. The four diets were grass hay (H) alone (group H), H with barley (group H + B), H with DDGS for the whole feeding period (27 d) (group H + DDGS) or H and DDGS for 5 d (d 8–12 of oestrus cycle) (group H + DDGS5). Serum progesterone concentrations were affected by oestrus cycle (p < 0.001), but not by dietary treatments. However, feeding H + DDGS caused significant increases in serum insulin, leptin and growth hormone concentrations (p < 0.05). In Experiment 2, 30 ewes were divided into 2 groups (n = 15), receiving DDGS or soybean meal (SBM) during the prepartum period. Diets had no significant effect on weights of dams or lambs at birth; however, the weaning weights of lambs born from ewes of group DDGS were significantly higher (p < 0.05). Moreover, serum glucose, blood urea nitrogen, triglyceride and beta hydroxybutyric acid (BHBA) concentrations during the prepartum period were affected by dietary treatments and by time (p < 0.001). During the prepartum period, BHBA concentrations of ewes fed SBM were higher, while BHBA levels decreased during the last weeks of pregnancy regardless of diet. Lamb serum immunoglobulin G concentrations increased from 1 h to 24 h after birth (p < 0.001). Colostrum of ewes fed SBM had higher fat-free dry matter (DM) and protein contents in comparison to colostrum of ewes fed DDGS (p < 0.05). In conclusion, DDGS can be included as protein source in pregnancy rations up to 15% of DM to obtain reproductive performance outcomes equal to or exceeding those obtained with SBM.     

Estimation of utilisable crude protein at the duodenum of dried distillers’ grains with solubles using a modified gas test

The objective of this study was to characterise the variation of utilisable crude protein at the duodenum (uCP) of dried distillers’ grains with solubles (DDGS) for ruminants using a modified gas test and to predict the uCP in DDGS based on chemical composition. Thirteen samples originating from wheat, maize, barley or blends of different substrates were studied. The in vitro uCP was estimated using the modified Hohenheim gas test (moHGT). Samples were incubated in rumen fluid for 8 h, 24 h and 48 h followed by ammonia distillation. The obtained values were compared to reference values of uCP (based on the contents of crude protein (CP), in situ undegraded CP and metabolisable energy). The reference and in vitro values of uCP were calculated according to passage rates of 2, 5 and 8%/h (i.e., uCP₂, uCP₅ and uCP₈, respectively). The in vitro uCP₈ ranged from 214 to 320 g/kg DM and reference values from 158 to 302 g/kg DM. The in vitro uCP₂ was on average lower (by 7 g/kg DM) and in vitro uCP₈ was higher (by 56 g/kg DM) than their respective reference values. The in vitro uCP₅ and uCP₈ were correlated with reference values and the correlations were improved with increasing passage rates. When the differences of uCP content between in vitro and reference values were related to CP fractions, they increased with increasing content of CP fraction A and decreasing content of CP fraction B3 for uCP₈. The prediction of uCP values from chemical composition was not reliable. It was concluded that uCP can be predicted on the basis of the moHGT method and CP fractions. The accuracy of prediction improved upon the inclusion of CP fractions and neutral-detergent insoluble nitrogen. The present study revealed a significant variation in the uCP content of DDGS, which should be considered when formulating rations for dairy cows.     

In situ ruminal degradation of amino acids and in vitro protein digestibility of undegraded CP of dried distillers’ grains with solubles from European ethanol plants

The objectives of this study were to compare the in situ ruminal degradation of CP and amino acids (AAs) of dried distillers’ grains with solubles (DDGS), and to estimate intestinal digestibility (ID) of undegradable crude protein (UDP) with the in vitro pepsin–pancreatin solubility of CP (PPS), using either DDGS samples (DDGS-s) or DDGS residues (DDGS-r) obtained after 16 h ruminal incubation. Thirteen samples originating from wheat, corn, barley and blends were studied. Lysine and methionine content of DDGS-s varied from 1.4 to 4.0 and 1.3 to 2.0 g/16 g N, respectively. The milk protein score (MPS) of DDGS-s was low and ranged from 0.36 to 0.51, and lysine and isoleucine were estimated to be the most limiting AAs in DDGS-s and DDGS-r. DDGS-r contained slightly more essential AAs (EAAs) than did the DDGS-s. Rumen degradation after 16 h varied from 44% to 94% for CP, from 39% to 90% for lysine and from 35% to 92% for methionine. Linear regressions showed that the ruminal degradation of individual AAs can be predicted from CP degradation. The PPS of DDGS-s was higher than that of DDGS-r and it varied from 70% to 89% and from 47% to 81%, respectively. There was no significant correlation between the PPS of DDGS-s and PPS of DDGS-r (R²=0.31). The estimated intestinally absorbable dietary protein (IADP) averaged 21%. Moderate correlation was found between the crude fibre (CF) content and PPS of DDGS-r (R²=0.43). This study suggests an overestimation of the contribution of UDP of DDGS to digestible protein supply in the duodenum in some currently used protein evaluation systems. More research is required and recommended to assess the intestinal digestibility of AAs from DDGS.     

Inclusion of sunflower seed and wheat dried distillers’ grains with solubles in a red clover silage-based diet enhances steers performance,meat quality and fatty acid profiles

The current study compared beef production, quality and fatty acid (FA) profiles of yearling steers fed a control diet containing 70 : 30 red clover silage (RCS) : barley-based concentrate, a diet containing 11% sunflower seed (SS) substituted for barley, and diets containing SS with15% or 30% wheat dried distillers’ grain with solubles (DDGS). Additions of DDGS were balanced by reductions in RCS and SS to maintain crude fat levels in diets. A total of two pens of eight animals were fed per diet for an average period of 208 days. Relative to the control diet, feeding the SS diet increased (P<0.05) average daily gain, final live weight and proportions of total n-6 FA, non-conjugated 18:2 biohydrogenation products (i.e. atypical dienes) with the first double bond at carbon 8 or 9 from the carboxyl end, conjugated linoleic acid isomers with the first double bond from carbon 7 to 10 from the carboxyl end, t-18:1 isomers, and reduced (P<0.05) the proportions of total n-3 FA, conjugated linolenic acids, branched-chain FA, odd-chain FA and 16:0. Feeding DDGS-15 and DDGS-30 diets v. the SS diet further increased (P<0.05) average daily gains, final live weight, carcass weight, hot dressing percentage, fat thickness, rib-eye muscle area, and improved instrumental and sensory panel meat tenderness. However, in general feeding DGGS-15 or DDGS-30 diets did not change FA proportions relative to feeding the SS diet. Overall, adding SS to a RCS-based diet enhanced muscle proportions of 18:2n-6 biohydrogenation products, and further substitutions of DDGS in the diet improved beef production, and quality while maintaining proportions of potentially functional bioactive FA including vaccenic and rumenic acids.     

Nutrient availability of different batches of wheat distiller’s dried grains with solubles for turkeys

Effects of five different batches of wheat distiller’s dried grains with solubles (DDGS) were used to investigate bioavailability of energy and nutrients for turkeys. The laboratory analysis of the DDGS showed the largest variations for soluble non-starch polysaccharides, oil and ash. In total, 96 birds were fed one of six mash diets. The basal diet contained per kilogram 535 g wheat and 300 g soya bean meal, corresponding to 247 g crude protein and 12.6 MJ N-corrected apparent metabolisable energy (AMEn). Another five diets contained per kilogram 200 g of each DDGS samples in replacement for basal diet. Each diet was fed to eight pens with two female Premium turkeys following randomisation. The AMEn and the nutrient retention coefficients of the pure DDGS samples were obtained using the substitution method. The AMEn of the DDGS from batch A was higher (p = 0.048) compared to those from batches B and C, but did not differ from DDGS samples D and E. There were no differences in dry matter retention, nitrogen retention and fat digestibility between the DDGS samples tested. The AMEn of the DDGS samples correlated positively (p < 0.05) to the starch (r = 0.895) and the non-soluble non-starch polysaccharides contents (r = 0.940), and the red index of lighting (a) (r = 0.916), respectively. In general, findings from this study indicate bioavailability of energy and most nutrients to be in the range of published data with turkeys, and to vary between batches.     

Effects of supplementation with corn distillers’ dried grains on animal performance,nitrogen balance,and enteric CH4 emissions of young Nellore bulls fed a high-tropical forage diet

The inclusion of corn-dried distillers’ grains (DDG) could be an alternative supplement to increase animal performance, nitrogen efficiency usage (NEU), and decrease enteric methane (CH₄) emissions. Our goal was to determine whether DDG could replace a traditional supplement (cottonseed meal) without affecting animal performance, N balance, and CH₄ emissions. The experiment was conducted during the forage growing season (December to April), with 15 d adaptation, and a 112 d experimental period. The experimental design was completely randomized with four treatments: a mineral supplement (MS), cottonseed meal supplement (CS), 50% replacement of CS by DDG (50DDG), and 100% replacement of CS by DDG (100DDG). Cottonseed meal and DDG were used as protein supplement. A total of 12 paddocks, 3 per treatment, were used to measure forage mass: morphological and chemical composition of forage, forage allowance, and animal performance. Six animals per treatment were used to evaluate DM intake, digestibility, CH₄ emissions, microbial protein production (MCP), and NEU of each treatment. Eighty-one Young Nellore bulls (48 testers, 12 per treatments and 33 adjusters) with initial BW of 255 ± 5 kg (10–12 months old) were supplemented with each supplement type at a level of 0.3% of BW. Pasture management was continuous stocking with a variable stocking rate (put-and-take). Enteric CH₄ was measured using the gas tracer technique. The MCP was quantified using purine derivatives and the NEU mass balance. No differences were found in nutrient intake (P > 0.228). Individual animal performance and gain per area were higher in the treatments with concentrates compared with that of MS; however, there was no difference among treatments CS, 50DDG, and 100DDG. The ADG was 0.83 for MS and 1.08 kg/animal/d when supplemented (P < 0.05). Gain per hectare was 709 kg/ha for MS and 915 kg/ha when supplemented with concentrates (P < 0.05). There was no difference in CH₄ production among treatments that average 180 g/animal/d; however, CH₄ per kg of gain was reduced with CS. The CH₄ conversion factor averaged 5.91%. There was no difference in the synthesis of MCP and NEU. Corn DDG can replace 100% of cottonseed meal as a protein source for supplementation of young Nellore bulls grazing in tropical pastures without affecting animal performance, NEU, MCP, and CH₄ emissions.     

An Alternative Approach in Gateway® Cloning when the Bacterial Antibiotic Selection Cassettes of the Entry Clone and Destination Vector are the Same

The Gateway^® recombination technology has revolutionized the method of gene cloning for functional analyses and high-throughput ORFeome projects. In general, Gateway cloning is highly efficient because after LR recombination and bacterial transformation, only cells containing the recombinant destination clone are selected on an antibiotic selection plate. However, when the antibiotic resistance gene for bacterial selection is the same in the entry and destination vectors, the direct selection of recombinant destination clones on an antibiotic plate is difficult. Here, we demonstrate an efficient and comprehensive approach to obtain positive destination clones directly on an antibiotic selection plate in this situation. The strategy involves polymerase chain reaction (PCR)-mediated amplification of the entry clone using entry vector-specific primers that bind outside the attL sequences and the subsequent use of this purified PCR product for LR recombination with the destination vector. Our results suggest that cloning of linear DNA fragments into circular destination vectors through LR recombination is an efficient method for inserts up to 7 kb in size. Using this approach, the yield of colony PCR positive destination clones was 100 % for genes of various sizes tested in our experiments.     

Composition of the fauna and the communities’ structure of the Cicadina (Homoptera) in the lowland Trans-Volga woodlands

179 species of 7 families of the Cicadina were found in the lowland Trans-Volga woodlands within Nizhniy Novgorod Province, the Republic of Mari El, and Chuvashia. Thirty-tree commonest species were distinguished, and their abundance was compared. Comparison of the species composition of the Cicadina complexes in the model biotopes has shown the greatest similarity between the complexes in the birch forests and spruce forests.     

Effects of the acid–base treatment of corn on rumen fermentation and microbiota,inflammatory response and growth performance in beef cattle fed high-concentrate diet

Beef cattle are often fed high-concentrate diet (HCD) to achieve high growth rate. However, HCD feeding is strongly associated with metabolic disorders. Mild acid treatment of grains in HCD with 1% hydrochloric acid (HA) followed by neutralization with sodium bicarbonate (SB) might modify rumen fermentation patterns and microbiota, thereby decreasing the negative effects of HCD. This study was thus aimed to investigate the effects of treatment of corn with 1% HA and subsequent neutralization with SB on rumen fermentation and microbiota, inflammatory response and growth performance in beef cattle fed HCD. Eighteen beef cattle were randomly allocated to three groups and each group was fed different diets: low-concentrate diet (LCD) (concentrate : forage = 40 : 60), HCD (concentrate : forage = 60 : 40) or HCD based on treated corn (HCDT) with the same concentrate to forage ratio as the HCD. The corn in the HCDT was steeped in 1% HA (wt/wt) for 48 h and neutralized with SB after HA treatment. The animal trial lasted for 42 days with an adaptation period of 7 days. At the end of the trial, rumen fluid samples were collected for measuring ruminal pH values, short-chain fatty acids, endotoxin (or lipopolysaccharide, LPS) and bacterial microbiota. Plasma samples were collected at the end of the trial to determine the concentrations of plasma LPS, proinflammatory cytokines and acute phase proteins (APPs). The results showed that compared with the LCD, feeding the HCD had better growth performance due to a shift in the ruminal fermentation pattern from acetate towards propionate, butyrate and valerate. However, the HCD decreased ruminal pH and increased ruminal LPS release and the concentrations of plasma proinflammatory cytokines and APPs. Furthermore, feeding the HCD reduced bacterial richness and diversity in the rumen. Treatment of corn increased resistant starch (RS) content. Compared with the HCD, feeding the HCDT reduced ruminal LPS and improved ruminal bacterial microbiota, resulting in decreased inflammation and improved growth performance. In conclusion, although the HCD had better growth performance than the LCD, feeding the HCD promoted the pH reduction and the LPS release in the rumen, disturbed the ruminal bacterial stability and increased inflammatory response. Treatment of corn with HA in combination with subsequent SB neutralization increased the RS content and helped counter the negative effects of feeding HCD to beef steers.     

Thermal tolerance of tropical and temperate alpine plants suggests that ‘mountain passes are not higher in the tropics’

Aim

Tolerance of species to extreme temperatures largely determines their distribution and vulnerability to climate change. We examined thermal tolerance in tropical and temperate alpine plants, testing the hypotheses that: (a) temperate plants are resistant to more extreme temperatures and have an overall wider thermal tolerance breadth (TTB); (b) TTB in temperate plants is wider than TTB in tropical plants during the entire growing season; (c) resistance to frost and heat varies during the season in temperate plants but not in tropical plants; (d) TTB of a species predicts its latitudinal range.

Location

Tropical (Ecuador, Bolivia) and temperate (USA, Austria) mountains.

Time period

Four periods of the growing season (2014, 2016–2019).

Major taxa

Ninety-six vascular plant species.

Methods

We employed the electrolyte leakage method to estimate the temperature resistance, that is, the temperature at which 50% tissue injury (Lt50) occurs in leaves. We used phylogenetic linear mixed-effect models in a Bayesian framework to test for differences between the plant groups.

Results

Temperate and tropical plants do not differ in their temperature resistance. The four hypotheses are rejected since: (a) temperate plants do not have significantly wider overall TTB compared to tropical plants, (b) TTB of temperate plants is wider than TTB of tropical plants only at the end of the temperate summer, (c) seasonal acclimation is observed in both plant groups, (d) the latitudinal range of the plants is not related to TTB.

Main conclusions

The lack of TTB differences between temperate and tropical alpine plants is consistent with trends observed in ectothermic animals, which suggests a general latitudinal pattern in high-elevation poikilotherm organisms. Limited acclimation capacity to cope with long freezing exposures restricts the occurrence of tropical alpine species to thermally aseasonal environments making them particularly vulnerable to climate change.     

Plant and animal communities in brackish supra-littoral pools (‘dobben’) in the northern part of the Netherlands

Fifty brackish supra-littoral pools bordering the Waddenzee were studied. The structure of plant communities (Potamogeton pectinatus L., Ranunculus baudotii Godr. and Zannichellia pedunculata Rchb.) is discussed in relation to water level fluctuations, chlorinity and water transparency. Chlorinity tolerances of the macrophytes (7 species) are discussed. The macrofauna was studied semi-quantitatively. The aquatic Coleoptera had the greatest diversity (24 species). A distinct relationship between the number of Coleoptera species and the percentage of macrophyte coverage was found. The distribution patterns of the most frequent species with respect to chlorinity categories are shown in histograms. The number of aquatic Heteroptera species is also discussed in relation to chlorinity and vegetation coverage. Less important macrofaunal groups (the Crustacea, Mollusca and Odonata) occurred in low species numbers.     

Effects of the supplementation of distillers’ grape residues on ruminal degradability,whole tract digestibility and nitrogen metabolism in sheep

ABSTRACT

Five ruminally and duodenally cannulated Kazakh male lambs (30 ± 2.75 kg) maintained singly in a metabolic cage were used in a 5 × 5 Latin square experiment to investigate the effect of supplementing a ration with five different levels of distillers’ grape residue (DGR) on ruminal degradability, whole tract digestibility and nitrogen (N) metabolism of growing lambs. The rations were isoenergetic and isonitrogenous and contained 0, 3.85, 7.70, 11.55 and 15.41% DGR (DM basis). Each experimental period lasted for 18 d: 10 d for adaptation to the dietary treatment and 8 d for faecal, urinary, ruminal and duodenal digesta sample collections. The outflow rate of ruminal digesta increased (p = 0.032) linearly with the increased level of dietary neutral detergent fibre content, caused by the supplementation of DGR. As a result, the effective degradability of dry matter and crude protein decreased significantly with the treatments. Although the dietary intake of N, duodenal flow of total N, and the endogenous N at the duodenum were not affected by experimental treatments, N fractions in the digesta were altered. Ruminal microbial N decreased (p < 0.01) linearly; in contrast, ruminal un-degradable protein increased linearly (p < 0.01) in response to the increased addition of DGR. Although there was no significant difference in faecal N among treatments, N retention was increased linearly (p = 0.014), owing to the remarkable reduction (p = 0.016) of urinary N excretion with an increasing level of DGR. The results indicate that the DGR has some potential benefits of increasing the supply of bypass protein and of improving the utilisation efficiency of N for sheep. Therefore, the supplementation of DGR in ruminant feeding is recommended at levels not exceeding 10% of the diet.     

Endo-β-mannanase isoforms are present in the endosperm and embryo of tomato seeds, but are not essentially linked to the completion of germination

A current hypothesis is that endo--mannanase activity in the endosperm cap of tomato (Lycopersicon esculentum Mill. cv. Moneymaker) seeds is induced by gibberellin (GA) and weakens the endosperm cap thus permitting radicle protrusion. We have tested this hypothesis. In isolated parts, the expression of endo--mannanase in the endosperm after germination is induced by GAs, but the expression of endo--mannanase in the endosperm cap prior to radicle protrusion is not induced by GAs. Also, abscisic acid (ABA) is incapable of inhibiting endo--mannanase activity in the endosperm cap, even though it strongly inhibits germination. However, ABA does inhibit enzyme activity in the endosperm and embryo after germination. There are several isoforms in the endosperm cap and embryo prior to radicle protrusion that are tissue-specific. Tissue prints showed that enzyme activity in the embryo spreads from the radicle tip to the cotyledons with time after the start of imbibition. The isoform and developmental patterns of enzyme activity on tissueprints are unaffected when seeds are incubated in ABA, even though germination is inhibited. We conclude that the presence of endo--mannanase activity in the endosperm cap is not in itself sufficient to permit tomato seeds to complete germination.Abbreviations ABA cis/trans-abscisic acid - GA(s) gibberellin(s) - IEF isoelectric focussing - pI(s) isoelectric point(s) We thank Dr. Bruce Downie for the seemingly endless but inspiring discussions.     

Bacterial Composition of the Human Upper Gastrointestinal Tract Microbiome Is Dynamic and Associated with Genomic Instability in a Barrett’s Esophagus Cohort

Background

The incidence of esophageal adenocarcinoma (EAC) has increased nearly five-fold over the last four decades in the United States. Barrett’s esophagus, the replacement of the normal squamous epithelial lining with a mucus-secreting columnar epithelium, is the only known precursor to EAC. Like other parts of the gastrointestinal (GI) tract, the esophagus hosts a variety of bacteria and comparisons among published studies suggest bacterial communities in the stomach and esophagus differ. Chronic infection with Helicobacter pylori in the stomach has been inversely associated with development of EAC, but the mechanisms underlying this association remain unclear.

Methodology

The bacterial composition in the upper GI tract was characterized in a subset of participants (n=12) of the Seattle Barrett’s Esophagus Research cohort using broad-range 16S PCR and pyrosequencing of biopsy and brush samples collected from squamous esophagus, Barrett’s esophagus, stomach corpus and stomach antrum. Three of the individuals were sampled at two separate time points. Prevalence of H. pylori infection and subsequent development of aneuploidy (n=339) and EAC (n=433) was examined in a larger subset of this cohort.

Results/Significance

Within individuals, bacterial communities of the stomach and esophagus showed overlapping community membership. Despite closer proximity, the stomach antrum and corpus communities were less similar than the antrum and esophageal samples. Re-sampling of study participants revealed similar upper GI community membership in two of three cases. In this Barrett’s esophagus cohort, Streptococcus and Prevotella species dominate the upper GI and the ratio of these two species is associated with waist-to-hip ratio and hiatal hernia length, two known EAC risk factors in Barrett’s esophagus. H. pylori-positive individuals had a significantly decreased incidence of aneuploidy and a non-significant trend toward lower incidence of EAC.