Reproductive responses of ram lambs under short-term exposure to endophyte-infected tall fescue seed

Our objective was to determine the influence of short-term exposure to endophyte-infected tall fescue on reproductive function of ram lambs. Rams (214 days of age) were fed a diet free of endophyte-infected fescue seed (EF; n = 8) or endophyte-infected fescue seed (EI; n = 9; 34% of diet; 4.8 μg g⁻¹ ergovaline) for 6 weeks. Feed offered to EF rams, individually fed, was reduced to the average intake of EI lambs from previous day so that intake was similar between treatments and averaged 2.4% BW (DM basis), leading to daily intake of 33.7 μg ergovaline kg⁻¹ BW for the EI fed lambs. Daily high ambient temperature for the trial ranged between 16 and 26 °C. Respiration rate and rectal temperature were measured at 14:00 daily. Blood was collected for serum concentrations of prolactin (weekly) and testosterone (twice weekly). Body weight and body condition scores (BCS; 1 = thin; 5 = fat) were determined every 14 days. Scrotal circumference, scrotal skin temperature, and semen characteristics were determined weekly. Rams were slaughtered after 6 weeks of feeding. Signs of fescue toxicosis in EI fed rams included increased rectal temperature (P < 0.001, R² = 0.11) and respiration rate (day, P < 0.001, R² = 0.25) when high ambient temperature exceeded 22 °C and reduced serum concentrations of prolactin (diet × day, P < 0.001). Body weight of EI fed rams tended to decrease after 36 days of feeding compared with EF fed rams (−3.0 kg versus 0.51 kg; P < 0.07) and BCS was similar between treatment throughout the trial. Serum concentrations of testosterone were greater in EI compared with EF fed rams (diet × day, P < 0.005, R² = 0.08). Scrotal skin temperature, scrotal circumference, semen volume, percent sperm motility, and percent abnormal sperm were similar between treatments. Spermatozoa concentration tended to be greater in EF compared with EI fed rams after 43 days of feeding (P < 0.10; R² = 0.15). Rate of forward movement of spermatozoa tended to increase at a greater rate between Days 8 and 29 in EF compared with EI fed rams (diet × day, P < 0.08). Feeding endophyte-infected fescue seed to ram lambs was associated with potential decreased fertility and increased serum concentrations of testosterone. Short term exposure of endophyte toxins to male ruminants may negatively impact reproductive responses. Feeding for longer periods may further reduce fertility and merits further research.     

Effects of untreated and heat-treated canola presscake on milk yield and composition of dairy cows

Five primiparous and five multiparous Holstein cows were used in two Latin square design experiments to determine effects of feeding unheated and heated canola presscake on milk yield and composition, and milk fatty acid concentrations of lactating dairy cows. Five diets that differed in level and source of dietary fat were formulated: a low fat control diet with 30 g kg⁻¹ fat from tallow, an unheated canola presscake supplemented diet (50 g kg⁻¹ fat), a heated canola presscake supplemented diet (50 g kg⁻¹ fat), a high tallow plus unheated canola meal supplemented diet (50 g kg⁻¹ fat), and a high tallow plus heated canola meal supplemented diet (50 g kg⁻¹ fat). In sacco ruminal degradability of heated and unheated canola presscake was compared with that of heated and unheated canola meal in a randomized complete block design using two ruminally fistulated cows. Heat treatment reduced ruminal DM and CP degradability of canola presscake. Multiparous cows fed diets supplemented with heated or unheated canola presscake produced more milk than those fed diets containing similar levels of fat from tallow with heated or unheated canola meal, respectively. High levels of fat from any diet reduced milk fat percentage for cows of either parity. Feeding heated canola products increased milk and milk protein yields in primiparous cows only, but cows of both parities fed diets containing canola presscake produced milk with lower concentrations of C12:0, C14:0, and C16:0 fatty acids than cows fed the canola meal and tallow diets, although concentrations of C18:1 n-9 were unaffected by fat source or level. Feeding canola products to dairy cows can alter milk fatty acid profile, but only primiparous cows have increased productivity as a result of feeding heated, versus unheated, canola presscake.     

Ruminal nitrogen disappearance from sod-seeded cereal grain forages in Northern Arkansas

Wheat (Triticum aestivum L.), oat (Avena sativa L.) and rye (Secale cereale L.) were overseeded into a dormant bermudagrass (Cynodon dactylon (L.) Pers.) sod and harvested on six dates throughout the spring. Plant growth stage was documented for each forage on each harvest date, and harvested forages were subsequently evaluated for forage quality characteristics. Four ruminally cannulated steers were used to evaluate disappearance kinetics of nitrogen (N) by an in situ method. All forages had high concentrations of N (≥31.1 g kg⁻¹ DM) throughout harvest dates in March. By 15 April, rye had reached a substantially more advanced growth stage than either wheat or oat. This trait, coupled with the concurrent taller growth habit, caused concentrations of N in rye to decline (P<0.05) rapidly between the 24 March and 4 May harvest dates. The effective ruminal disappearance of N remained high (≥790 g kg⁻¹ N) for all forages harvested through mid-April, thereby indicating that these cereal-grain forages exhibit the same characteristics of high N disappearance and low potential ruminal escape that are commonly observed in other high-quality cool season grasses harvested at similar growth stages. The effective disappearance of N reached a minimum (P<0.05) for all forages immediately before grain fill. Generally, substantial increases (P<0.05) in effective ruminal disappearance of N were observed as these forages partitioned N into the filling grain head. Fractional rates of N disappearance for wheat and rye were extremely rapid (≥0.383 h⁻¹) during grain fill. However, rye also exhibited an extremely rapid disappearance rate (0.548 h⁻¹) immediately prior to the onset of grain fill that was not observed for wheat (0.085 h⁻¹) at an identical growth stage. Parameters associated with disappearance kinetics can be related to growth stage at harvest by linear and polynomial regression techniques, although the best fit model was dependent on forage type.     

Effects of yeast culture (Saccharomyces cerevisiae) on ruminal digestion in non-lactating dairy cows

Six non-lactating dairy cows fitted with ruminal cannulas were used in a cross-over design, to investigate the effects of supplemental yeast culture (Saccharomyces cerevisiae) (YC) and interaction of YC by sampling time on ruminal fermentation and in situ fibre degradation. Cows were fed twice daily with a diet composed of 67% corn silage, 32% concentrate and 1% vitamin and mineral mixture, on a dry matter (DM) basis. Concentrates were not mixed with silage. YC (0.5% DM) significantly decreased rumen ammonia from 148.5 mg l⁻¹ to 103.1 mg l⁻¹ 3 h post-feeding, and significantly increased by about 20% the concentration of total volatile fatty acids before and 1 h after feeding. YC significantly increased molar percentage of propionate and decreased the acetate : propionate ratio before feeding. No significant effect was observed on ruminal pH and molar percentages of acetate or butyrate. Pattern of degradation of DM, neutral and acid detergent fibre from hay was affected, with a cubic effect of interaction of YC by incubation time. However, magnitude of degradation was not significantly different at any time. These results show that modifications of ruminal fermentation due to YC addition are time dependent when the diet is fed twice daily.     

Influence on dithiolopyrrolone antibiotic production by organic acids in Saccharothrix algeriensis NRRL B-24137

The influence of organic acids on growth and dithiolopyrrolone antibiotic production by Saccharothrix algeriensis NRRL B-24137 was studied. The production of dithiolopyrrolones depends upon the nature and concentration of the organic acids in the culture medium. Study of the nature of organic acids showed that the most effective organic acids for thiolutin specific production were maleic, 4-hydroxybenzoic, benzentetracarboxylic, pantothenic, pivalic and pyruvic acids (which yielded almost five-fold over the starting medium) and pimelic acid (more than three-fold). 4-Bromobenzoic acid showed the best production of senecioyl-pyrrothine (59 mg g⁻¹ DCW). Tiglic acid showed the best production of tigloyl-pyrrothine (22 mg g⁻¹ DCW). The highest yield of isobutyryl-pyrrothine (7.6 mg g⁻¹ DCW) was observed in the presence of crotonic acid. Sorbic acid yielded the best production of butanoyl-pyrrothine (26 mg g⁻¹ DCW). Methacrylic, butyric, pyruvic and 4-bromobenzoic acids also exhibited the best production of butanoyl-pyrrothine (27–11-fold).Study of organic acid concentration showed that among the selected organic acids, pimelic acid yielded the highest specific production of thiolutin (91 mg g⁻¹ DCW) at 7.5 mM; and senecioyl-pyrrothine (11 mg g⁻¹ DCW), tigloyl-pyrrothine (9 mg g⁻¹ DCW) and butanoyl-pyrrothine (3.5 mg g⁻¹ DCW) at 5 mM. Pyruvic acid at 1.25 mM enhanced the production of senecioyl-pyrrothine (4.3 mg g⁻¹ DCW). The maximum production of tigloyl-pyrrothine (18.6 mg g⁻¹ DCW) was observed in the presence of tiglic acid at 2.5 mM. Maximum production of isobutyryl-pyrrothine was observed in the presence of 7.5 mM tiglic acid. In addition, methacrylic acid (at 5 mM) and butyric acid (at 2.5 mM) enhanced the production of butanoyl-pyrrothine (26 and 20 times, respectively).The above results can be employed in the optimisation of the culture medium for the production of dithiolopyrrolone in higher quantities.     

Effects of phosphorus and nitrogen amendments on the growth of Egeria najas

The effect of nutrient addition on the growth of E. najas was evaluated in a dose response experiment using sand amended with phosphorus (P) and nitrogen (N), and in enrichment trials with N and P amendments to natural sediments. Plants, water and sediment came from lagoons of the Upper Paraná River Floodplain and from Itaipu Reservoir (Brazil). Relative growth rates (RGRs) of E. najas shoots, based on dry mass (DM), varied from 0.03 to 0.060 d⁻¹ for both nutrients. Root:shoot biomass ratios were related to sediment exchangeable P (r = −0.419; P = 0.03) and N (r = −0.54; P = 0.006), however root RGR was not related to sediment nutrient concentrations. When natural sediments were amended with N and P, neither shoot nor root RGRs differed among treatments for substrata from either the reservoir or the floodplain lagoons (P > 0.05). Comparison of nutrient concentrations measured in natural sediments collected from several sites in both the Upper Paraná River Floodplain (range 49–213 μg P g⁻¹ DM; 36–373 μg N g⁻¹ DM) and Itaipu Reservoir (range 43–402 μg P g⁻¹ DM; 7.9–238 μg N g⁻¹ DM) showed that sediment N and P from these systems usually exceeded minimum requirements necessary for E. najas growth, as measured in the dose response experiment. Together, these results indicate that E. najas, at least in early stages of development, responds to sediment nutrient amendments and relies upon bottom sediments to meet its N and P requirements and that for at least two Brazilian ecosystems, growth of this species is not limited by insufficient sediment N or P. Thus, reducing N and P in water is not enough to control E. najas growth in short time periods in these ecosystems.     

Estimation of the phosphorus requirement of weanling pigs fed supplemental phytase

Studies were conducted with crossbred weanling pigs to determine the level of phosphorus needed to be fed when a maize–soyabean meal–whey diet was supplemented with exogenous phytase (Natuphos™). In Trial 1, phytase was added at 1200 phytase units (PTU) kg⁻¹ as phosphorus decreased. The control diet in Phase I (0–14 days) contained 7.3 g kg⁻¹ phosphorus and in Phase II (14–28 days) contained 6.5 g kg⁻¹ phosphorus. Dietary phosphorus was calculated to decrease by 0.8, 1.6 or 2.4 g kg⁻¹ when phytase was supplemented. Chromic oxide was added for estimation of apparent absorption of phosphorus. Performance was optimum when 5.7 and 4.8 g kg⁻¹ phosphorus (analysed levels) were fed with 1200 PTU kg⁻¹ phytase in Phases I and II, respectively. The lowest dietary phosphorus levels did not reduce performance for the overall 28-day period. Apparent phosphorus digestibility was increased by phytase in Phase I when 5.7 g kg⁻¹ phosphorus was fed compared to the control diet and in Phase II when 6.0 g kg⁻¹ phosphorus was fed with phytase. Faecal phosphorus excretion decreased in both phases as dietary phosphorus decreased. Faecal phosphorus excretion was minimized at the lowest phosphorus level with no decrease in performance. The estimated requirement for dietary phosphorus, as determined by the NLIN procedure, is 5.0 g kg⁻¹ in Phase I and 4.3 g kg⁻¹ in Phase II when 1200 PTU kg⁻¹ is used. In Trial 2, phytase was supplemented at 500 PTU kg⁻¹ when phosphorus was decreased in the diet. The control diet contained 6.6 and 6.0 g kg⁻¹ phosphorus in Phases I and II, respectively, and phosphorus was calculated to decrease by 0.5, 1.0, 1.5, or 2.0 g kg⁻¹ when phytase was added. Daily gain decreased when 5.0 g kg⁻¹ phosphorus was fed in Phase I and when 4.6 or 4.2 g kg⁻¹ (analysed levels) phosphorus was fed in Phase II with 500 PTU kg⁻¹. Faecal phosphorus excretion decreased as dietary phosphorus decreased, but there were no treatment effects on apparent phosphorus digestibility. The dietary phosphorus requirement was estimated to be 5.7 and 5.0 g kg⁻¹ in Phases I and II, respectively, when phytase is fed at 500 PTU kg⁻¹. At the present recommendation of 500 PTU kg⁻¹ in starter feed, phosphorus can be decreased by 0.10 g kg⁻¹. However, higher levels of phytase are needed to actually increase apparent phosphorus digestibility.     

Protocorm culture of Dendrobium candidum in balloon type bubble bioreactors

Protocorm cultures of Dendrobium candidum were established in balloon type bubble bioreactors using Murashige and Skoog (MS) medium with 0.5 mg l⁻¹ α-naphthaleneacetic acid (NAA), 2.5% (w/v) sucrose, 5:25 mM NH₄:NO₃ and 1% (v/v) banana homogenate for the production of biomass and bioactive compounds. In 3 l bioreactor containing 2 l medium, a maximum protocorm biomass (21.0 g l⁻¹ dry biomass) and also optimum quantities of total polysaccharides (389.3 mg g⁻¹ DW), coumarins (18.0 mg g⁻¹ DW), polyphenolics (11.9 mg g⁻¹ DW), and flavonoids (4.5 mg g⁻¹ DW) were achieved after 7 weeks of culture. Based on these studies, 5 and 10 l bioreactor cultures were established to harvest 80 g and 160 g dry biomass. In 10 l bioreactors, the protocorms grown were accumulated with optimal levels of polysaccharides (424.1 mg g⁻¹ DW), coumarins (15.8 mg g⁻¹ DW), polyphenols (9.03 mg g⁻¹ DW) and flavonoids (4.7 mg g⁻¹ DW). The bioreactor technology developed here will be useful for the production of important bioactive compounds from D. candidum.     

NOB suppression and adaptation strategies in the partial nitrification–Anammox process for a poultry manure anaerobic digester

Poultry manure contains high levels of ammonia, which result in a suboptimal bioconversion to methane in anaerobic digesters (AD). A simultaneous process of nitrification, Anammox and denitrification (SNAD) in a continuous granular bubble column reactor to treat the anaerobically digested poultry manure was implemented. Thus, two strategies to achieve high efficiencies were proposed in this study: (1) ammonia overload to suppress nitrite oxidizing bacteria (NOB) and (2) gradual adaptation of the partial nitrification–Anammox (PN–A) biomass to organic matter. During the NOB-suppression stage, microbial and physical biomass characterizations were performed and the NOB abundance decreased from 31.3% to 3.3%. During the adaptation stage, with a nitrogen loading rate of 0.34 g L⁻¹ d⁻¹, a hydraulic retention time of 1.24 d and an influent COD/N ratio of 2.63 ± 0.02, a maximum ammonia and total nitrogen removal of 100% and 91.68% were achieved, respectively. The relative abundances of the aerobic and the anaerobic ammonia-oxidizing bacteria were greater than 35% and 40% respectively, during the study. These strategies provided useful design tools for the efficient removal of nitrogen species in the presence of organic matter.     

Non-phytin phosphorus requirements of commercial broilers and White Leghorn layers

Experiments were conducted to determine the optimum requirements of non-phytin phosphorus (NPP) in commercial broilers and White Leghorn layers. Five levels of NPP (2.5, 3.0, 3.5, 4.0 and 4.5 g kg⁻¹ diet) were tested to assess the NPP requirement of commercial broilers (3–30 days of age) fed maize–soya diets containing 10 g Ca kg⁻¹. Each level of NPP was fed to quadruplicate groups of ten chicks each. Inclusion of graded levels of NPP significantly (P < 0.01) influenced body weight gain, feed intake, tibia ash content, phosphorus content in serum, tibia ash and phosphorus retention. The predicted NPP requirements for body weight gain, P content in serum and tibia ash were 4.4, 4.48 and 4.1 g kg⁻¹ diet, respectively. The NPP requirement for tibia ash was the highest (7.4 g kg⁻¹ diet). Similarly, four levels of NPP (2.0, 2.5, 3.0 and 3.5 g kg⁻¹ diet) were tested with maize–soya diets containing 35 g Ca kg⁻¹ for White Leghorn layers (266–350 days of age). Each diet was tested on four groups of 12 hens in each. Egg production was not influenced by the variation in dietary NPP levels. The predicted NPP requirements for better egg weight and shell thickness were 2.6 and 2.4 g kg⁻¹ diet, respectively, while for the serum inorganic P level the value was 3.42 g kg⁻¹ diet. Therefore, it can be concluded that commercial broilers need about 4.4 g NPP kg⁻¹ diet for better performance, whereas, White Leghorn layers need not more than 2.0 g NPP kg⁻¹ diet for better egg production. However, layers require 2.6 g NPP kg⁻¹ diet to produce eggs with better egg size and shell quality.     

Seasonal shifts in seagrass bed primary producers in a cold-temperate estuary: Dynamics of eelgrass Zostera marina and associated epiphytic algae

The seasonal dynamics of seagrass and epiphytic algal primary production were measured in an eelgrass (Zostera marina) bed in the Akkeshi-ko estuary, Hokkaido, Japan (43°02′N, 144°52′E). During spring and early summer, eelgrass biomass increased, with a high production (maximum: 2.89 g C m⁻² day⁻¹), but the production and biomass of epiphytic algae remained low. In contrast, epiphytic algae bloomed in August, with a high production (5.21 g C m⁻² day⁻¹), but eelgrass production ceased and its biomass subsequently decreased. Therefore, the major primary producers in this eelgrass bed switched seasonally from eelgrass in spring and early summer to epiphytic algae in late summer and autumn. Epiphytic algae maintained similar productivity because of the change of photosynthetic kinetics and the dominant epiphytic diatom changed from highly adhesive species to less adhesive or filamentous small species during the bloom. This suggests that the change of epiphyte density and biomass was due to change of its loss rate, possibly due to herbivorous grazing rate. Moreover, competition between epiphytic algae and eelgrass for nutrients and light may also affect the dramatic seasonal changes in the major primary producers.     

Production of a new exopolysaccharide (EPS) by Pseudomonas oleovorans NRRL B-14682 grown on glycerol

Pure glycerol and glycerol-rich product (GRP) obtained from the biodiesel industries were used as carbon source for the production of a new extracellular polysaccharide (EPS) by Pseudomonas oleovorans NRRL B-14682. The influence of temperature (20–40 °C) and pH (6.0–8.0) was studied. A temperature of 30 °C and pH control at 6.8 gave the maximum cell growth and EPS production. The culture attained a maximum cell dry weight (CDW) of 9.55 g l⁻¹ and an EPS concentration of 11.82 g l⁻¹ when cultivated with pure glycerol. GRP was a suitable carbon source, as shown by the slightly higher EPS concentration (12.18 g l⁻¹). The EPS productivity obtained with GRP (3.85 g l⁻¹ d⁻¹) was almost twice that obtained with pure glycerol (2.00 g l⁻¹ d⁻¹). Also, the yield on glycerol was higher for the cultivation with GRP (0.36 g g⁻¹) than for pure glycerol (0.28 g g⁻¹). The EPS was a high molecular weight heteropolysaccharide, composed by neutral sugars (37–80 wt% galactose, 2–30 wt% glucose, 0.5–25 wt% mannose and 0.5–20 wt% rhamnose) and containing acyl group substituents (pyruvil, acetyl and succinyl were identified). The EPS forms highly viscous aqueous dispersions with many potential commercial applications.     

Galactose-limited fed-batch cultivation of Escherichia coli for the production of lacto-N-tetraose

Lacto-N-tetraose (Gal(β1-3)GlcNAc(β1-3)Gal(β1-4)Glc) is one of the most abundant oligosaccharide structures in human milk. We recently described the synthesis of lacto-N-tetraose by a whole-cell biotransformation with recombinant Escherichia coli cells. However, only about 5% of the lactose was converted into lacto-N-tetraose by this approach. The major product obtained was the intermediate lacto-N-triose II (GlcNAc(β1-3)Gal(β1-4)Glc).In order to improve the bioconversion of lactose to lacto-N-tetraose, we have investigated the influence of the carbon source on the formation of lacto-N-tetraose and on the intracellular availability of the glycosyltransferase substrates, UDP-N-acetylglucosamine and UDP-galactose. By growth of the recombinant E. coli cells on D-galactose, the yield of lacto-N-tetraose (810.8 mg L⁻¹ culture) was 3.6-times higher compared to cultivation on D-glucose.Using fed-batch cultivation with galactose as sole energy and carbon source, a large-scale synthesis of lacto-N-tetraose was demonstrated. During the 26 h feeding phase the growth rate (μ = 0.05) was maintained by an exponential galactose feed. In total, 16 g L⁻¹ lactose were fed and resulted in final yields of 12.72 ± 0.21 g L⁻¹ lacto-N-tetraose and 13.70 ± 0.10 g L⁻¹ lacto-N-triose II. In total, 173 g of lacto-N-tetraose were produced with a space-time yield of 0.37 g L⁻¹ h⁻¹.     

Simultaneous saccharification and fermentation of kraft pulp by recombinant Escherichia coli for phenyllactic acid production

Simultaneous saccharification and fermentation (SSF) of renewable cellulose for the production of 3-phenyllactic acid (PhLA) by recombinant Escherichia coli was investigated. Kraft pulp recovered from biomass fractionation processes was used as a model cellulosic feedstock and was hydrolyzed using 10–50 filter paper unit (FPU) g⁻¹ kraft pulp of a commercial cellulase mixture, which increased the glucose yield from 21% to 72% in an enzyme dose-dependent manner. PhLA fermentation of the hydrolyzed kraft pulp by a recombinant E. coli strain expressing phenylpyruvate reductase from Wickerhamia fluorescens TK1 produced 1.9 mM PhLA. The PhLA yield obtained using separate hydrolysis and fermentation was enhanced from 5.8% to 42% by process integration into SSF of kraft pulp (20 g L⁻¹) in a complex medium (pH 7.0) at 37 °C. The PhLA yield was negatively correlated with the initial glucose concentration, with a five-fold higher PhLA yield observed in culture medium containing 10 g L⁻¹ glucose compared to 100 g L⁻¹. Taken together, these results suggest that the PhLA yield from cellulose in kraft pulp can be improved by SSF under glucose-limited conditions.     

Enhancement of polysaccharide production in suspension cultures of protocorm-like bodies from Dendrobium huoshanense by optimization of medium compositions and feeding of sucrose

A strategy that optimization of medium compositions for maximum biomass followed by feeding of sucrose for maximum polysaccharide synthesis was developed for enhancing polysaccharide production in suspension culture of protocorm-like bodies (PLBs) of Dendrobium huoshanense C.Z. Tang et S.J. Cheng. In growth stage, the original half-strength MS medium was optimized with carbon sources, nitrogen sources and metal ion combinations. The effects of different carbon sources on PLBs growth were remarkable and sucrose at 35 g l⁻¹ was the most suitable. Sole nitrate nitrogen of 30 mmol l⁻¹ was the best for PLBs growth. Metal ions (Ca²⁺, Fe²⁺, Mn²⁺ and Zn²⁺) showed different influences on PLBs growth. The optimal concentration of Ca²⁺, Fe²⁺, Mn²⁺ and Zn²⁺ was 4.5 mmol l⁻¹, 0.1 mmol l⁻¹, 0.5 mmol l⁻¹ and 0.06 mmol l⁻¹, respectively. In the optimized medium (sucrose, nitrate, Ca²⁺, Fe²⁺, Mn²⁺ and Zn²⁺ concentration as described above, the other component concentration seen in half-strength MS), 33.9 g DW l⁻¹ PLBs were harvested after 30 days of culture and biomass increase was improved 245% as compared with that in the original medium. In production stage, polysaccharide synthesis was significantly improved by the feeding sucrose. The maximum polysaccharide production (22 g l⁻¹) was obtained in the case of 50 g l⁻¹ sucrose feeding at day 30 of culture, which was about 109-fold higher than that in the original medium without feeding of sucrose.     

Volatile fatty acids accumulation and rhamnolipid generation in situ from waste activated sludge fermentation stimulated by external rhamnolipid addition

The solubilization and acidification of waste activated sludge (WAS) were apparently enhanced by external rhamnolipid (RL) addition. The maximum solute carbohydrate concentrations increased linearly from 48 ± 5 mg COD L⁻¹ in the un-pretreated WAS (blank) to 566 ± 19 mg COD L⁻¹, and protein increased from 1050 ± 8 to 3493 ± 16 mg COD L⁻¹ at RL dosage of 0.10 g g⁻¹ TSS. The highest VFAs concentration peaked at 3840 mg COD L⁻¹ at RL dosage of 0.04 g g⁻¹ TSS, which was 4.24-fold higher than the blank test. RL was generated in situ during WAS fermentation when external RL was added. It was detected that RL concentration was increased from initial 880 ± 92 mg L⁻¹ to 1312 ± 7 mg L⁻¹ at the end of 96 h with RL dosage of 0.04 g g⁻¹ TSS, which was increased to 1.49-fold. Meanwhile, methane production was notably reduced to a quite low level of 2.0 mL CH₄ g⁻¹ VSS, showing effective inhibition of methanogens by RL (58.8 mL CH₄ g⁻¹ VSS in the blank). In addition, the activity of hydrolytic enzymes (protease and α-glucosidase) was enhanced accordingly. VFAs accumulation and RL generation in situ demonstrated that the additional RL substantially performed enhanced biological effects for waste activated sludge fermentation.     

Effects of soybean oligosaccharides on intestinal microbial communities and immune modulation in mice

BackgroundSoybean oligosaccharides (SBOSs) are potential prebiotics that may be used to improve immune function. Here, we investigated the effects of intragastric administration of SBOSs in mice to determine the effects on autochthonous intestinal microbial communities and immunological parameters. Results E: After 22-day administration, 4.0 g kg body weight (BW)⁻¹ SBOSs significantly enhanced the proliferation of bifidobacteria and lactic acid bacteria (LAB) as compared to the control. This dose of SBOSs also significantly increased numbers of enterococci and decreased numbers of Clostridium perfringens. Treatment with 4.0 g kg BW⁻¹ SBOSs also significantly increased the percentage of T-lymphocytes and lymphocyte proliferation as compared to the control, suggesting that SBOSs promoted cellular immunity in mice. Additionally, 4.0 g kg BW⁻¹ SBOSs induced significant differences in hemolysin production, natural killer (NK) cell activity, phagocytic activity, cytokine production, and immunoglobulin levels compared to the control. Conclusion: Our data demonstrated that intragastric administration of SBOSs at a dose of 4.0 g kg BW⁻¹ improved the numbers of beneficial intestinal microbes and enhanced immunological function of mice. Therefore, these data supported that SBOSs may have applications as a prebiotic to improve immune responses in humans. Further studies are warranted.     

Operation of a bioelectrochemical system as a polishing stage for the effluent from a two-stage biohydrogen and biomethane production process

Anaerobic bioenergy production processes including fermentative biohydrogen (BioH₂), anaerobic digestion (AD) and bioelectrochemical system have been investigated for converting municipal waste or various biomass feedstock to useful energy carriers. However, the performance of a microbial fuel cell (MFC) fed on the effluent from a two-stage biogas production process has not yet been investigated extensively in continuous reactor operation on complex substrates. In this study we have investigated the extent to which a microbial fuel cell (MFC) can reduce COD and recover further energy from the effluent of a two-stage biohydrogen and biomethane system. The performance of a four-module tubular MFC was determined at six different organic loadings (0.036–6.149 g sCOD L⁻¹ d⁻¹) in terms of power generation, COD removal efficiency, coulombic efficiency (CE) and energy conversion efficiency (ECE). A power density of 3.1 W m⁻³ was observed at the OLR = 0.572 g sCOD L⁻¹ d⁻¹, which resulted in the highest CE (60%) and ECE (0.8%), but the COD removal efficiency decreased at higher organic loading rates (35.1–4.4%). The energy recovery was 92.95 J L⁻¹ and the energy conversion efficiency, based on total influent COD was found to be 0.48–0.81% at 0.572 g sCOD L⁻¹ d⁻¹. However, the energy recovery by the MFC is only reported for a four-module reactor and improved performance can be expected with an extended module count, as chemical energy remained available for further electrogenesis.     

Effects of supplemental urea sources and feeding frequency on ruminal fermentation,fiber digestion,and nitrogen balance in beef steers

The objective of two experiments was to evaluate non-protein N supplementation with protected urea sources in terms of rumen fermentation products, nutrient digestibility, and N balance in ruminally fistulated beef steers (initial bodyweight 239 ± 18 kg) fed switchgrass hay. Experiment 1 compared urea with Optigen II^®, and Experiment 2 compared urea with RumaPro^®. In both experiments, supplements (400 g/kg of daily dietary dry matter) were fed once daily or every 2 h in a balanced design. Supplements contained soybean hulls, corn grain, vitamins, and minerals as well as non-protein N sources. Non-protein N provided 0.18 g/g of dietary N. Switchgrass hay was fed once daily, at the same time as the supplement in the once-daily treatments. Dry matter intake (4.1 kg/d in Experiment 1, 4.5 kg/d in Experiment 2), dry matter digestibility (P<0.25, 0.58 ± 0.014 g/g in Experiment 1, 0.58 ± 0.010 g/g in Experiment 2), N balance (P<0.83, 11.3 ± 1.9 g/d in Experiment 1, 11.8 ± 3.6 g/d in Experiment 2), ruminal ammonia concentrations (P<0.29, 15.2 ± 1.4 mM in Experiment 1, 11.8 ± 0.6 mM in Experiment 2), and ruminal short-chain fatty acid concentrations (P<0.13, 77.7 ± 3.0 mM in Experiment 1, 75.4 ± 3.0 mM in Experiment 2) were not affected by feeding protected urea sources. Providing a steady supply of ruminally degradable N by feeding supplement every 2 h vs once daily decreased ruminal ammonia concentrations by approximately one-half by 4 h after feeding hay (P<0.01 in both experiments) and increased (P<0.02 in Experiment 1, P<0.08) in Experiment 2) apparent digestibility of dry matter (0.58–0.62 in Experiment 1, 0.56–0.61 in Experiment 2) and dietary fiber components.     

Continuous production of ellagic acid in a packed-bed reactor

Ellagic acid is a high-value bioactive compound that is used in the food, cosmetic and pharmaceutical industries. The aim of this work was to develop a continuous system for ellagic acid production. Ellagitannase produced by solid-state fermentation and attached to polyurethane foam particles was used as a biocatalyst in a continuous bioreactor for the hydrolysis of ellagitannins from pomegranate by-product. A packed-bed reactor containing the biocatalyst (22.22 Units per gram of dry solid, U gds⁻¹) was fed with a pomegranate ellagitannins solution (0.1%, w/v) at a flow rate of 0.27 mL min⁻¹ at 60 °C. The bioreactor completed several biotransformations while maintaining the hydrolysis rate (60%) with a half-life of 10 continuous cycles of ellagic acid production. Volumetric productivity and ellagic acid yield were 1.09 g L⁻¹ h⁻¹ and 235.89 mg g⁻¹ of pomegranate ellagitannins during the first 70 min of hydrolysis, respectively. The developed biocatalyst showed good operational and mechanical stability and may be successfully used for ellagitannin hydrolysis in a continuous system. This is the first report of high-yield continuous production of ellagic acid using an auto-immobilized enzyme.