Production Of Valerate Research Articles

Anaerobic production of valeric acid from crude glycerol via chain elongation

Glycerol from biodiesel production was used as a substrate for valerate production in a 13.1-L anaerobic filter with an open microbiome. Ethanol at 15% of the influent chemical oxygen demand was supplemented as an additional electron donor source. The 114-day experimental period was divided in three phases which included initial adaptation phase, external sludge addition from a caproic acid producing reactor and valerate extraction using a pertraction system. Propionate (0.63–1.75 g COD L−1 day−1) and valerate (0.86–1.81 g COD L−1 day−1) were the main carboxylates formed throughout all operational phases. An increase in production rates of butyrate (0.26–0.31 g COD L−1 day−1), caproate (0.01–0.08 g COD L−1 day−1), and 1,3-propanediol (0.43–0.52 g COD L−1 day−1) was observed with addition of external caproic acid producing sludge rich in Clostridium members. In the operational phase with pertraction, a sudden decrease in 1,3-propanediol and concomitant increase in acid production were verified. Propionate and valerate reached higher production rates compared with the other two phases, suggesting that the pertraction system favored the oxidative pathway of glycerol fermentation. Valerate extraction reached a maximum of 30 g COD m−2 day−1. The filter microbiome was highly diverse with Simpson index values close to 0.1 for the four sludge samples collected, and a concomitant increase in Megasphaera elsdenii and an increase in valerate production rates were observed. Hence, high valerate production and extraction rates through the carboxylate platform are a feasible alternative for crude glycerol valorization with a great potential for improvement in future research.

Elevated concentrations of crude glycerin in diets for beef cattle: feedlot performance, carcass traits, and ruminal metabolism1.

Three experiments were conducted to evaluate the inclusion of crude glycerin (CG) in diets for beef cattle. In Exp. 1, 4 ruminally cannulated steers were fed diets with 0 or 15% CG (DM basis), to evaluate DM disappearance, VFA profiles, and gas production. There was a tendency for an interaction (P = 0.06) between diet fed to donor animals and substrate fed to in vitro system, and digestion was increased when CG was added to cultures with ruminal fluid from CG-fed animals. Total VFA were unaffected by diets or by substrate incubated. The CG increased production of propionate, butyrate, and valerate (P < 0.01) while the gas production was unaffected (P = 0.16). In Exp. 2, 24 crossbred heifers (334.4 ± 0.9 kg BW) were fed the same diets as Exp. 1, for 35 d. Fecal grab samples were collected 3 times daily on day 7, 21, and 35, to evaluate total tract digestibilities of DM, OM, and NDF. The CG improved digestibility of diet OM (P = 0.04), and DM followed a similar trend (P = 0.06), while the NDF digestibility was unaffected (P = 0.29). In Exp. 3, crossbred heifers (n = 374; 375.8 ± 36.1 kg BW) were used to evaluate feedlot performance and carcass traits when fed diets with 0, 7.5, or 15% CG, with or without added 0.3% salt. Heifers were assigned to 25 pens and were harvested on day 125. Removing salt from CG-based diets did not impact performance (P = 0.50). The CG did not influence average daily gain (P = 0.27), but decreased DM intake (P = 0.003), USDA Yield Grade (P = 0.01), and improved feed efficiency (P = 0.03), while tended to decrease USDA prime carcasses (P = 0.10). Carcass weight (P = 0.24), Longissimus muscle area (P = 0.63), and kidney, pelvic, heart fat (P = 0.59) were unaffected by CG. Twelfth-rib fat was less for heifers fed 15% CG without salt compared with the other treatments (P = 0.005), while marbling was less for heifers fed CG diets compared with the control-fed animals (linear, P = 0.004; quadratic, P = 0.02). In conclusion, GC can replace dry-rolled corn in diets for beef heifers when fed at 15% of diet DM, improving OM digestion, increasing ruminal propionate and butyrate without affecting greenhouse gas emissions. Feeding up to 15% CG improves feed efficiency but depresses marbling and tends to decrease Quality Grade. Removing supplemental salt from CG-diets has no impact on performance or carcass traits.

Genetic parameters of plasma and ruminal volatile fatty acids in sheep fed alfalfa pellets and genetic correlations with enteric methane emissions1.

Animal-to-animal variation in methane (CH4) emissions determined in respiration chambers has a genetic basis, but rapid phenotyping methods that can be applied on-farm are required to enable increased genetic progress by the farming industry. Fermentation of carbohydrates in the rumen results in the formation of VFA with hydrogen (H2) as a byproduct that is used for CH4 formation. Generally, fermentation pathways leading to acetate are associated with the most H2 production, less H2 formation is associated with butyrate production, and propionate and valerate production are associated with reduced H2 production. Therefore, VFA may constitute a potential correlated proxy for CH4 emissions to enable high-throughput animal screening. The objective of the present study was to determine the genetic parameters for ruminal and plasma VFA concentrations in sheep fed alfalfa (Medicago sativa L.) pellets and their genetic (rg) and phenotypic (rp) correlations with CH4 emissions. Measurements of CH4 emissions in respiration chambers and ruminal (stomach tubing 18 h from last meal) and blood plasma (3 h post-feeding) VFA concentrations were made on 1,538 lambs from 5 birth years (2007 and 2009 to 2012) aged between 5 and 10 mo, while the animals were fed alfalfa pellets at 2.0 times maintenance requirements in 2 equal size meals (0900 and 1500 h). These measurements were repeated twice (rounds) 14 d apart. Mean (± SD) CH4 production was 24.4 ± 3.08 g/d, and the mean CH4 yield was 15.8 ± 1.51 g/kg DMI. Mean concentration of total ruminal VFA was 52.2 mM, with concentrations of acetate, propionate and butyrate of 35.97, 8.83, and 4.02 mM, respectively. Ruminal total VFA concentration had heritability (h2) and repeatability estimates (± SE) of 0.24 ± 0.05 and 0.35 ± 0.03, respectively, and similar estimates were found for acetate, propionate, and butyrate. Blood plasma concentrations of VFA had much lower estimates of h2 and repeatability than ruminal VFA. Genetic correlations with CH4 yield were greatest for total concentrations of ruminal VFA and acetate, with 0.54 ± 0.12 and 0.56 ± 0.12, respectively, which were much greater than their corresponding rp. The rp and rg of ruminal VFA proportions and blood VFAs with CH4 emissions were in general lower than for ruminal VFA concentrations. However, minor ruminal VFA proportions had also moderate rg with CH4 yield. Pre-feeding concentrations of total VFA and acetate were the strongest correlated proxies to select sheep that are genetically low CH4 emitters.

Modified anaerobic digestion model No.1 (ADM1) for modeling anaerobic digestion process at different ammonium concentrations.

Anaerobic digestion (AD) is an established method for sustainable energy production. Anaerobic digestion model No.1 (ADM1) was used to simulate methane production (MP) and volatile fatty acid (VFA) concentrations at different ammonium concentrations. In accordance with the incomplete description of several biochemical reactions and the omission of several reaction processes, ADM1 was modified with the consideration of acetic acid inhibition and valeric acid existence. ADM1_ac (ADM1 added acetic acid inhibition) could obtain better simulation accuracy of MP (goodness-of-fit value=0.945), and VFA concentrations (goodness-of-fit values>0.39) were all higher than ADM1_original, but cannot explain the valeric acid production. ADM1_va (ADM1 added valeric acid existence) could achieve better simulation of valeric acid (achieving a breakthrough of zero), nevertheless the accuracy of propionic and butyric acids was poorer than ADM1_ac with differences between experimental and simulation values were 5%-10% lower. With both factors coordinated, MP and VFA concentrations could be simulated accurately by ADM1_ac_va (ADM1 added acetic acid inhibition and valeric acid existence), with the highest goodness-of-fit values (>0.85). The results of a verification experiment with ADM1_ac_va simulation further indicated that acetic acid inhibition and valeric acid as new component were both important in ADM1. PRACTITIONER POINTS: ADM1_ac could simulate MP and acetate, propionate and butyrate concentrations better. ADM1_va could explain the valerate production during AD of glucose. ADM1_ac_va could simulate AD process quite accurately, with the highest goodness-of-fit values (>0.85). Acetate inhibition and valerate existence were both important and should be considered in ADM1.

Valerate production by Megasphaera elsdenii isolated from pig feces

Megasphaera elsdenii is able to produce several short-chain fatty acids (SCFAs), such as acetate, propionate, butyrate, and valerate. These SCFAs serve as an energy source for host animals and play an important role in gut health. In this study, M.elsdenii was isolated from pig feces that had been collected from two farms located in distinct areas of Japan. These M.elsdenii isolates were genotyped, and 7 representative strains were selected. When these 7 strains and M.elsdenii JCM 1772T were cultured with lactate for 24h, all 7 strains produced valerate as a predominant SCFA. Therefore, the valerate-producing M.elsdenii inhabits a wide area of Japan. In contrast, M.elsdenii JCM 1772T produced acetate, propionate, butyrate, and valerate at similar levels. When the Y2 strain, one of the 7 representative strains, was cultured without lactate, low levels of valerate accumulated. In contrast, in a time course of lactate fermentation by the Y2 strain, lactate was rapidly consumed, and acetate and propionate were produced after 6h of incubation. Thereafter, acetate and propionate were consumed from 6 to 12h after the start of the incubation, and valerate and butyrate were produced. In most of the previously described M.elsdenii strains, valerate was not a predominant SCFA. Therefore, the M.elsdenii Y2 strain showed an unique metabolism in which valerate was produced as a primary end product of lactate fermentation.

Influence of malic acid-heat treatment for protecting sunflower protein against ruminal degradation on in vitro methane production: A comparison with the use of malic acid as an additive

Batch cultures of rumen microorganisms were used to compare the fermentation of sunflower seed (SS) and meal (SM) treated with malic acid and heat (MAH; 150°C for 1h) to protect the protein from ruminal degradation with that of the untreated samples supplemented the same amount of malate (as additive), either as free acid (MA) or disodium malate (DSM). As previous studies have shown the influence of donors’ diet on in vitro fermentation, cultures were inoculated with ruminal fluid from four sheep fed a medium-concentrate diet (MC; 50:50 hay:concentrate) or a high-concentrate diet (HC; 15:85 barley straw:concentrate) in a cross-over experimental design. Cultures were sampled at 6 and 16.5h of fermentation. In 16.5h incubations, MAH treatment reduced (P<0.001) CH4 production and ammonia-N concentrations for both substrates (by 60.3 and 45.3% for SS and by 23.7 and 17.2% for SM substrate, respectively). Whereas the MAH treatment reduced total volatile fatty (VFA) production by 16.5% for SS substrate, no effects were observed for SM substrate (P=0.441). For both substrates, adding the same amount of MA to untreated samples (as a feed additive) resulted in greater CH4 production and ammonia-N concentrations compared with the MAH treatment. A positive relationship (P<0.001) was observed between the concentrations of NH3N and CH4 production at both incubation times for both substrates. Compared with the untreated feeds, MA and DSM did not affect (P>0.05) CH4 production for either substrate, but reduced ammonia-N concentrations (13.8%; P=0.004) for SM substrate. Compared with DSM, MA treatment resulted in greater (P<0.05) production of gas, butyrate, isovalerate and valerate and tended (P<0.10) to greater total VFA, and propionate production for SS substrate at 6h incubation, but most differences disappeared after 16.5h incubation. For some fermentation parameters, the response to MAH treatment was more pronounced by using fluid from sheep fed the HC diet than that from MC-fed sheep. In conclusion, the MAH treatment was more effective at reducing CH4 emissions and NH3N concentrations than the supplementation of malic acid or disodium malate as a feed additive.

Design and Control of Reactive Distillation Process for the Production of Methyl Valerate

Methyl valerate (VAME), also known as methyl pentanoate, is a methyl ester of pentanoic acid (valeric acid). VAME is usually used as a fragrance in the production of beauty care, soap, and laundry detergents. High purity VAME can also be used as a kind of plasticizer. This study presents design details of the process for the manufacture of VAME. A reactive distillation column (RDC) is used in the production process to overcome equilibrium limitation of the esterification reaction. There is no bottom outlet of this RDC. Both products, VAME and water, are withdrawn from the distillate of RDC and then can be separated by two strippers and a decanter. A thermally coupled design is then developed to reduce the remixing effect in the rectifying section of the RDC. The simulation results show that 30% energy saving can be achieved by using the proposed thermally coupled configuration, but only 17% of total annual costs can be saved due to the use of a compressor. Control strategies of both conventional and therm...

Effects of virginiamycin and monensin administered alone or together with Megasphaera elsdenii strain NCIMB 41125 on in vitro production of lactate and VFA and the effects of monensin and M. elsdenii strain NCIMB 41125 on health and performance of feedlot steers

Virginiamycin (VIR) and monensin (MON) are included in high concentrate diets to mitigate digestive disturbances and to increase performance of ruminants in intensive systems. Megasphaera elsdenii strain NCIMB 41125 (Me) rapidly utilises lactate in the rumen, thereby controlling ruminal pH and digestive disturbances. Me promotes butyrate and valerate production whereas VIR and MON promote propionate that is gluconeogenic and perceived to be more favourable to performance. The objective of the present study was to determine whether the ratio between VFA proportions is more favourable when VIR or MON is administered together with Me and whether their respective effects on health and performance are additive. Two studies of factorial design were conducted, one in vitro fermentation trial where VIR or MON was incubated in the absence of Me (Me-) or in the presence of Me (Me+), and one in vivo trial with steers where MON or Me was administered alone or together. In the in vitro trial VIR and MON were administered to the fermentation vessels in two concentrations, a low dose (0.125µg/mL) and a high dose (0.375mg/mL). Me was administered at 100µL/40mL, supplying 2.5×105cfu/mL. In the in vivo trial 224 Bonsmara steers were allocated to a finishing diet with 80kg/ton roughage and 224 were allocated to a finishing diet with 20kg/ton roughage. Within each diet 112 steers received MON (MONY) and 112 not (MONN) and 112 steers within each diet were dosed with Me (MeY) and 112 not (MeN). In the in vitro trial VIRMe- and MONMe- decreased gas production, whereas VIRMe+ and MONMe+ increased fermentation. VIRMe- and to a lesser extent MONMe- increased total bacterial counts, a result which was apparently due to stimulation of M. elsdenii numbers as determined by 16R DNA sequencing, although other lactate utilising bacteria could have contributed. Me+ reduced lactate and the reduction was more in VIRMe+ and MONMe+. Fermentation end products in Me+ favoured butyrate and valerate and VIRMe- and especially MONMe-, propionate. VIRMe+ and MONMe+ displayed the median. In the steer trial MONY decreased intake and improved feed conversion efficiency. MONY increased carcass gain and dressing percentage on the 80kg/ton roughage diet but not the 20kg/ton roughage diet. Rumen score on both diets was improved by MONY and liver score by MONYMeY on the 20kg/ton roughage diet. Carcass weight was improved by MONNMeY on the 20kg/ton roughage diet. Morbidity and mortality were not affected by MONY but were improved in the presence of Me (MeY). In general, the results suggest synergy between MON and Me.

Production of medium-chain volatile fatty acids by mixed ruminal microorganisms is enhanced by ethanol in co-culture with Clostridium kluyveri

Mixed bacterial communities from the rumen ferment cellulosic biomass primarily to C2–C4 volatile fatty acids, and perform only limited chain extension to produce C5 (valeric) and C6 (caproic) acids. The aim of this study was to increase production of caproate and valerate in short-term in vitro incubations. Co-culture of mixed ruminal microbes with a rumen-derived strain of the bacterium Clostridium kluyveri converted cellulosic biomass (alfalfa stems or switchgrass herbage) plus ethanol to VFA mixtures that include valeric and caproic acids as the major fermentation products over a 48–72h run time. Concentrations of caproate reached 6.1gL−1, similar to or greater than those reported in most conventional carboxylate fermentations that employ substantially longer run times.

Production of Ethyl Valerate from Burkholderia cepacia Lipase Immobilized in Alginate

Production of Ethyl Valerate from Burkholderia cepacia Lipase Immobilized in Alginate Giovana S. Padilha*, de Barros M., Ranulfo M. Alegre, Elias B. Tambourgi Department of Food Engineering , School of Food Engineering, State University of Campinas (UNICAMP), University Campus Zeferino Vaz, Monteiro Lobato Street, 80, Zip Code:13083-862 , Campinas, SP, Brasil b Department of Engineering of Chemical Systems, School of Chemical Engineering, State University of Campinas (UNICAMP), University Campus “Zeferino Vaz”, Av. Albert Einstein, 500, Zip Code: 13083-970, Campinas, SP, Brazil giovana_padilha@yahoo.com.br

Comparison of updates to the Molly cow model to predict methane production from dairy cows fed pasture

Molly is a deterministic, mechanistic, dynamic model representing the digestion, metabolism, and production of a dairy cow. This study compared the predictions of enteric methane production from the original version of Molly (MollyOrigin) and 2 new versions of Molly. Updated versions included new ruminal fiber digestive parameters and animal hormonal parameters (Molly84) and a revised version of digestive and ruminal parameters (Molly85), using 3 different ruminal volatile fatty acid (VFA) stoichiometry constructs to describe the VFA pattern and methane (CH4) production (g of CH4/d). The VFA stoichiometry constructs were the original forage and mixed-diet VFA constructs and a new VFA stoichiometry based on a more recent and larger set of data that includes lactate and valerate production, amylolytic and cellulolytic bacteria, as well as protozoal pools. The models’ outputs were challenged using data from 16 dairy cattle 26 mo old [standard error of the mean (SEM)=1.7], 82 (SEM=8.7) d in milk, producing 17 (SEM=0.2) kg of milk/d, and fed fresh-cut ryegrass [dry matter intake=12.3 (SEM=0.3) kg of DM/d] in respiration chambers. Mean observed CH4 production was 266±5.6 SEM (g/d). Mean predicted values for CH4 production were 287 and 258g/d for MollyOrigin without and with the new VFA construct. Model Molly84 predicted 295 and 288g of CH4/d with and without the new VFA settings. Model Molly85 predicted the same CH4 production (276g/d) with or without the new VFA construct. The incorporation of the new VFA construct did not consistently reduce the low prediction error across the versions of Molly evaluated in the present study. The improvements in the Molly versions from MollyOrigin to Molly84 to Molly85 resulted in a decrease in mean square prediction error from 8.6 to 8.3 to 4.3% using the forage diet setting. The majority of the mean square prediction error was apportioned to random bias (e.g., 43, 65, and 70% in MollyOrigin, Molly84, and Molly85, respectively, on the forage setting, showing that with the updated versions a greater proportion of error was random). The slope bias was less than 2% in all cases. We concluded that, of the versions of Molly used for pastoral systems, Molly85 has the capability to predict CH4 production from grass-fed dairy cows with the highest accuracy.

Dynamics of Cathode-Associated Microbial Communities and Metabolite Profiles in a Glycerol-Fed Bioelectrochemical System

Electrical current can be used to supply reducing power to microbial metabolism. This phenomenon is typically studied in pure cultures with added redox mediators to transfer charge. Here, we investigate the development of a current-fed mixed microbial community fermenting glycerol at the cathode of a bioelectrochemical system in the absence of added mediators and identify correlations between microbial diversity and the respective product outcomes. Within 1 week of inoculation, a Citrobacter population represented 95 to 99% of the community and the metabolite profiles were dominated by 1,3-propanediol and ethanol. Over time, the Citrobacter population decreased in abundance while that of a Pectinatus population and the formation of propionate increased. After 6 weeks, several Clostridium populations and the production of valerate increased, which suggests that chain elongation was being performed. Current supply was stopped after 9 weeks and was associated with a decrease in glycerol degradation and alcohol formation. This decrease was reversed by resuming current supply; however, when hydrogen gas was bubbled through the reactor during open-circuit operation (open-circuit potential) as an alternative source of reducing power, glycerol degradation and metabolite production were unaffected. Cyclic voltammetry revealed that the community appeared to catalyze the hydrogen evolution reaction, leading to a +400-mV shift in its onset potential. Our results clearly demonstrate that current supply can alter fermentation profiles; however, further work is needed to determine the mechanisms behind this effect. In addition, operational conditions must be refined to gain greater control over community composition and metabolic outcomes.

Controlled biosynthesis of odd-chain fuels and chemicals via engineered modular metabolic pathways

Microbial systems are being increasingly developed as production hosts for a wide variety of chemical compounds. Broader adoption of microbial synthesis is hampered by a limited number of high-yielding natural pathways for molecules with the desired physical properties, as well as the difficulty in functionally assembling complex biosynthetic pathways in heterologous hosts. Here, we address both of these challenges by reporting the adaptation of the butanol biosynthetic pathway for the synthesis of odd-chain molecules and the development of a complementary modular toolkit to facilitate pathway construction, characterization, and optimization in engineered Escherichia coli. The modular feature of our pathway enables multientry and multiexit biosynthesis of various odd-chain compounds at high efficiency. By varying combinations of the pathway and toolkit enzymes, we demonstrate controlled production of propionate, trans-2-pentenoate, valerate, and pentanol, compounds with applications that include biofuels, antibiotics, biopolymers, and aroma chemicals. Importantly, and in contrast to a previously used method to identify limitations in heterologous amorphadiene production, our bypass strategy was effective even without the presence of freely membrane-diffusible substrates. This approach should prove useful for optimization of other pathways that use CoA-derivatized intermediates, including fatty acid β-oxidation and the mevalonate pathway for isoprenoid synthesis.

Methane production by ruminants

Methane is produced from carbon dioxide and hydrogen as a by-product of rumen fermentation. Excess hydrogen is produced together with the production of acetate and butyrate but not with the production of propionate and valerate. Diets lower in fibre and higher in starch result in higher proportions of propionate in the rumen volatile fatty acids and less methane per mole of substrate fermented. There is significant variation between animals in methane production. Research is underway to refine methane emissions factors for different classes of livestock. Smaller amounts of methane are also produced in the hind gut and from manure.

Mesophilic and Thermophilic Conditions Select for Unique but Highly Parallel Microbial Communities to Perform Carboxylate Platform Biomass Conversion

The carboxylate platform is a flexible, cost-effective means of converting lignocellulosic materials into chemicals and liquid fuels. Although the platform's chemistry and engineering are well studied, relatively little is known about the mixed microbial communities underlying its conversion processes. In this study, we examined the metagenomes of two actively fermenting platform communities incubated under contrasting temperature conditions (mesophilic 40°C; thermophilic 55°C), but utilizing the same inoculum and lignocellulosic feedstock. Community composition segregated by temperature. The thermophilic community harbored genes affiliated with Clostridia, Bacilli, and a Thermoanaerobacterium sp, whereas the mesophilic community metagenome was composed of genes affiliated with other Clostridia and Bacilli, Bacteriodia, γ-Proteobacteria, and Actinobacteria. Although both communities were able to metabolize cellulosic materials and shared many core functions, significant differences were detected with respect to the abundances of multiple Pfams, COGs, and enzyme families. The mesophilic metagenome was enriched in genes related to the degradation of arabinose and other hemicellulose-derived oligosaccharides, and the production of valerate and caproate. In contrast, the thermophilic community was enriched in genes related to the uptake of cellobiose and the transfer of genetic material. Functions assigned to taxonomic bins indicated that multiple community members at either temperature had the potential to degrade cellulose, cellobiose, or xylose and produce acetate, ethanol, and propionate. The results of this study suggest that both metabolic flexibility and functional redundancy contribute to the platform's ability to process lignocellulosic substrates and are likely to provide a degree of stability to the platform's fermentation processes.

Adaptation of healthy adult cats to select dietary fibers in vivo affects gas and short-chain fatty acid production from fiber fermentation in vitro

Nine young adult (1.73 ± 0.03 yr) male cats were used to determine the effects of microbial adaptation to select dietary fiber sources on changes in pH in vitro and on total and hydrogen gas, short-chain fatty acid (SCFA), and branched-chain fatty acid (BCFA) production. Cats were adapted to diets containing 4% cellulose, fructooligosaccharides (FOS), or pectin for 30 d before fecal sampling. Each cat was used as a single donor, and fecal inoculum was reacted with each of the aforementioned fiber substrates. Adaptation to dietary FOS resulted in a greater change in pH when exposed to FOS than pectin (adaptation × substrate, P < 0.001). When exposed to the FOS substrate, adaptation to dietary FOS or pectin increased hydrogen gas production (adaptation × substrate, P = 0.021). Adaptation to dietary FOS increased acetate and total SCFA production when exposed to FOS substrate in vitro (adaptation × substrate, P = 0.001). When exposed to the FOS substrate, propionate production tended to increase with adaptation to dietary cellulose (adaptation × substrate, P = 0.060). The BCFA + valerate tended to decrease with adaptation to dietary FOS when exposed to FOS substrate in vitro (adaptation × substrate, P = 0.092). Fructooligosaccharides resulted in the greatest change in pH and production of total gas (P < 0.001), hydrogen gas (P < 0.001), acetate (P < 0.001), propionate (P < 0.001), butyrate (P < 0.001), total SCFA (P < 0.001), and total BCFA + valerate production (P < 0.001). Adaptation to the FOS or pectin diet increased production of hydrogen gas with FOS and pectin substrates. Adaptation to pectin increased (P = 0.033) total gas production with FOS and pectin substrates. Overall, adaptation to either FOS or pectin led to greater SCFA and gas production, but adaptation to FOS resulted in the greatest effect overall.

Dietary adaptation of healthy adult cats to cellulose, fructooligosaccharides, or pectin modifies gas and short‐chain fatty acid production in vitro

Nine young adult male cats were used in a 3 × 3 factorial design to determine the effects of microbial adaptation to fiber type on changes in pH, total and hydrogen gas, short‐chain fatty acid (SCFA), and branched‐chain fatty acid (BCFA) production. Cats were adapted to a diet containing 4% cellulose, fructooligosaccharides (FOS), or pectin for 30 d prior to fecal sampling. Each cat was used as a single donor, and fecal inoculum was subjected to each of the aforementioned fiber substrates. Fructooligosaccharides produced the greatest changes in pH, total gas, hydrogen gas, acetate, propionate, butyrate, total SCFA, valerate, and total BCFA production (P&lt;0.001) regardless of adaptation to diet. Adaptation to the FOS or pectin diets increased production of total (P=0.043) and hydrogen (P=0.008) gas. Greater changes in pH (P&lt;0.001), acetate (P=0.001), and total SCFA (P=0.003) were observed for FOS and pectin substrates with adaptation to these respective substrates. Adaptation to the cellulose diet increased production of propionate (P=0.045) when exposed to the FOS or pectin substrates. Adaptation to the pectin diet increased production of valerate and total BCFA (P=0.039 and 0.022, respectively) when exposed to the cellulose or pectin substrates. Overall, adaptation to either FOS or pectin appear to increase SCFA and gas production.

Experience of a pilot-scale hydrogen-producing anaerobic sequencing batch reactor (ASBR) treating food waste

A pilot-scale H 2-producing anaerobic sequencing batch reactor (ASBR) treating food waste was operated. During the operation, the carbon/nitrogen (C/N) ratio was adjusted from 10 to 30 by changing the composition of the food waste. When the C/N ratio was lower than 20, the H 2 yield was maintained at around 0.5 mol H 2/mol hexose added, accounting for 2.3% of energy conversion efficiency contained in food waste to H 2, but it gradually dropped at higher C/N ratios. The low performance was accompanied by increased production of lactate, propionate, and valerate. In order to recover the performance, alkaline shock (pH 12.5 for 1 day) was imposed on the entire mixed liquor in the fermenter. This alkaline shock method was so effective that the H 2 yield significantly increased to over 0.9 mol H 2/mol hexose added, and was then stabilized at 0.69 mol H 2/mol hexose added. In addition, the settling characteristics of H 2-producing ASBR, which was separated into three layers, were investigated. Ribonucleic acid (RNA) as well as volatile suspended solid concentrations of each layer were measured to suggest how to enhance the H 2 production in ASBR operation.

Investigating unsaturated fat, monensin, or bromoethanesulfonate in continuous cultures retaining ruminal protozoa. I. Fermentation, biohydrogenation, and microbial protein synthesis

Methane is an end product of ruminal fermentation that is energetically wasteful and contributes to global climate change. Bromoethanesulfonate, animal-vegetable fat, and monensin were compared with a control treatment to suppress different functional groups of ruminal prokaryotes in the presence or absence of protozoa to evaluate changes in fermentation, digestibility, and microbial N outflow. Four dual-flow continuous culture fermenter systems were used in 4 periods in a 4×4 Latin square design split into 2 subperiods. In subperiod 1, a multistage filter system (50-μm smallest pore size) retained most protozoa. At the start of subperiod 2, conventional filters (300-μm pore size) were substituted to efflux protozoa via filtrate pumps over 3 d; after a further 7 d of adaptation, the fermenters were sampled for 3 d. Treatments were retained during both subperiods. Flow of total N and digestibilities of NDF and OM were 18, 16, and 9% higher, respectively, for the defaunated subperiod but were not different among treatments. Ammonia concentration was 33% higher in the faunated fermenters but was not affected by treatment. Defaunation increased the flow of nonammonia N and bacterial N from the fermenters. Protozoal counts were not different among treatments, but bromoethanesulfonate increased the generation time from 43.2 to 55.6h. Methanogenesis was unaffected by defaunation but tended to be increased by unsaturated fat. Defaunation did not affect total volatile fatty acid production but decreased the acetate:propionate ratio; monensin increased production of isovalerate and valerate. Biohydrogenation of unsaturated fatty acids was impaired in the defaunated fermenters because effluent flows of oleic, linoleic, and linolenic acids were 60, 77, and 69% higher, and the ratio of vaccenic acid:unsaturated FA ratio was decreased by 34% in the effluent. This ratio was increased in both subperiods with the added fat diet, indicating an accumulation of intermediates of biohydrogenation. However, the flow of 18:2 conjugated linoleic acid was unaffected by defaunation or by treatments other than added fat. The flows of trans-10, trans-11, and total trans-18:1 fatty acids were not affected by monensin or faunation status.

Effects of chicory inulin on ruminal fermentation in vitro

Bu araştırmanın amacı, farklı kaynaklardan gelen hindiba köklerinden elde edilen ve püskürtme tekniği ile kurutulmuş, inulinin in vitro ruminal fermantasyon üzerine etkilerini belirlemektir. Bu amaçla Rusitec tekniği (Rumen Simulation Technique) kullanılarak iki ayrı deneme yapıldı. Bu denemelerde 5 g/gün kuru ot ve 4 g/gün konsantre yemden oluşan bir rasyonun ruminal fermantasyonu, aynı rasyonun farklı kaynaklardan gelen inulinlerin varlığındaki fermantasyonu ile karşılaştırıldı. Birinci denemede Rusitec sistemin dokuz fermenterinden üçüne günde 1,5 g Hollanda, diğer üçüne de yine günde 1,5 g miktarında Danimarka kaynaklı inulin eklendi. Son üç fermentere ise hiçbir ilave yapılmayıp kontrol olarak kullanıldı. Bu araştırma düzeni ikinci denemede de aynen tekrarlandı, ancak burada Çin ve Almanya kökenli inulinler denendi. Kontrol ile karşılaştırıldığında, Çin ve Almanya kaynaklı inulinler ruminal pH’da belirgin bir azalmaya neden olurken, Hollanda ve Danimarka kökenli inulinler ruminal pH’da bir değişime yol açmadı. Danimarka ve Çin kaynaklı inulinler, toplam uçucu yağ asitleri, asetat, propiyonat, bütirat, iso-valerat ve valeratın günlük üretimlerinde artışa neden olurken, Hollanda kaynaklı inulin yalnızca bütirat, iso-valerat ve valerat miktarında artışa yol açtı. Çin kökenli inulin ise toplam uçucu yağ asitleri, asetat, bütirat, iso-valerat ve valerat üretimini artırdı. Kontrol fermenterleri ile karşılaştırıldığında, tüm inulin preparatlarının NH3-N konsantrasyonunu belirgin bir şekilde düşürdüğü tespit edildi. Organik madde sindirilebilirliği, Çin ve Almanya kökenli inulin uygulamalarından etkilenmedi, ancak Hollanda ve Danimarka kaynaklı inulinler organik madde sindirilebilirliğinde belirgin bir azalmaya neden oldu. Sonuç olarak kaynağı ile bağlantılı bir şekilde, inulinin in vitro ruminal fermantasyonu uyararak artırdığı ve özellikle ruminal amonyak konsantrasyonunun azaltılmasında etkili olduğu görüldü