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Sample records for continuous culture fermenters

  1. Kinetic Study of Acetone-Butanol-Ethanol Fermentation in Continuous Culture.

    Science.gov (United States)

    Buehler, Edward A; Mesbah, Ali

    2016-01-01

    Acetone-butanol-ethanol (ABE) fermentation by clostridia has shown promise for industrial-scale production of biobutanol. However, the continuous ABE fermentation suffers from low product yield, titer, and productivity. Systems analysis of the continuous ABE fermentation will offer insights into its metabolic pathway as well as into optimal fermentation design and operation. For the ABE fermentation in continuous Clostridium acetobutylicum culture, this paper presents a kinetic model that includes the effects of key metabolic intermediates and enzymes as well as culture pH, product inhibition, and glucose inhibition. The kinetic model is used for elucidating the behavior of the ABE fermentation under the conditions that are most relevant to continuous cultures. To this end, dynamic sensitivity analysis is performed to systematically investigate the effects of culture conditions, reaction kinetics, and enzymes on the dynamics of the ABE production pathway. The analysis provides guidance for future metabolic engineering and fermentation optimization studies.

  2. Enteric methane production and ruminal fermentation from forage brassica diets fed in continuous culture

    Science.gov (United States)

    Brassicas provide forage for livestock during the late fall when traditional perennial cool-season forages are not productive. However, little research exists on ruminal fermentation and methane(CH4) production of brassicas fed as forage. A continuous culture fermentor system was used to assess nutr...

  3. Effects of carbohydrates from citrus pulp and hominy feed on microbial fermentation in continuous culture.

    Science.gov (United States)

    Ariza, P; Bach, A; Stern, M D; Hall, M B

    2001-10-01

    Eight dual-flow continuous-culture fermenters were used to evaluate the effect of neutral detergent-soluble carbohydrates (NDSC) on fermentation by ruminal microorganisms. Citrus pulp and hominy feed were added to a basal diet as sources of NDSC, with citrus pulp providing neutral detergent-soluble fiber (NDSF) in the form of pectic substances and with hominy feed in the form of starch. The basal diet contained 26.7% corn silage, 6.0% alfalfa hay and 3.8% cottonseed hulls on a DM basis. The dried citrus pulp diet contained on a DM basis 17.2% CP, 34.7% NDF, 33.7% NDSC, and 14.4% NDSF, whereas the hominy feed diet contained 17.9% CP, 33.2% NDF, 35.9% NDSC, and 8.8% NDSF. Organic matter, DM, and NDF and ADF digestion were not affected by source of carbohydrate. Ammonia N concentration was greater (P citrus pulp diet (9.3 mg/100 mL). Total N, nonammonia N, microbial N, and dietary N flows were not affected by treatments; however, the efficiency of microbial protein synthesis was greater (P = 0.055) for the dried citrus pulp diet than for the hominy feed diet (30.6 vs 27.8 g of bacterial N/kg of OM truly digested). Results from this experiment indicate that NDSF from citrus pulp can provide similar sources of energy compared with starch from hominy feed to support ruminal microbial growth.

  4. Effect of oilseed source on ruminal fermentation and methane production of a grass-legume diet in continuous culture

    Science.gov (United States)

    Addition of oilseeds to pasture-based ruminant diets has been shown to decrease enteric CH4 emissions. However, little research has directly compared the effect of oilseed source on ruminal fermentation and Methane (CH4) production. A 4-unit continuous culture fermentor system was used to test 4 oil...

  5. Continuous energy recovery and nutrients removal from molasses wastewater by synergistic system of dark fermentation and algal culture under various fermentation types.

    Science.gov (United States)

    Ren, Hong-Yu; Kong, Fanying; Ma, Jun; Zhao, Lei; Xie, Guo-Jun; Xing, Defeng; Guo, Wan-Qian; Liu, Bing-Feng; Ren, Nan-Qi

    2017-12-29

    Synergistic system of dark fermentation and algal culture was initially operated at batch mode to investigate the energy production and nutrients removal from molasses wastewater in butyrate-type, ethanol-type and propionate-type fermentations. Butyrate-type fermentation was the most appropriate fermentation type for the synergistic system and exhibited the accumulative hydrogen volume of 658.3 mL L-1 and hydrogen yield of 131.7 mL g-1 COD. By-products from dark fermentation (mainly acetate and butyrate) were further used to cultivate oleaginous microalgae. The maximum algal biomass and lipid content reached 1.01 g L-1 and 38.5%, respectively. In continuous operation, the synergistic system was stable and efficient, and energy production increased from 8.77 kJ L-1 d-1 (dark fermentation) to 17.3 kJ L-1 d-1 (synergistic system). Total COD, TN and TP removal efficiencies in the synergistic system reached 91.1%, 89.1% and 85.7%, respectively. This study shows the potential of the synergistic system in energy recovery and wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Effect of low pH start-up on continuous mixed-culture lactic acid fermentation of dairy effluent.

    Science.gov (United States)

    Choi, Gyucheol; Kim, Jaai; Lee, Changsoo

    2016-12-01

    Mixed-culture fermentation that does not require an energy-intensive sterilization process is a viable approach for the economically feasible production of lactic acid (LA) due to the potential use of organic waste as feedstock. This study investigated mixed-culture LA fermentation of whey, a high-strength organic wastewater, in continuous mode. Variations in the hydraulic retention time (HRT) from 120 to 8 h under different pH regimes in two thermophilic reactors (55 °C) were compared for their fermentation performance. One reactor was maintained at a low pH (pH 3.0) during operation at HRTs of 120 to 24 h and then adjusted to pH 5.5 in the later phases of fermentation at HRTs of 24 to 8 h (R1), while the second reactor was maintained at pH 5.5 throughout the experiment (R2). Although the LA production in R1 was negligible at low pH, it increased dramatically after the pH was raised to 5.5 and exceeded that in R2 when stabilized at HRTs of 8 and 12 h. The maximum yield (0.62 g LA/g substrate fed as the chemical oxygen demand (COD) equivalent), the production rate (11.5 g/L day), and the selectivity (95 %) of LA were all determined at a 12-h HRT in R1. Additionally, molecular and statistical analyses revealed that changes in the HRT and the pH significantly affected the bacterial community structure and thus the fermentation characteristics of the experimental reactors. Bacillus coagulans was likely the predominant LA producer in both reactors. The overall results suggest that low pH start-up has a positive effect on yield and selectivity in mixed-culture LA fermentation.

  7. Influence of cobalt concentration on vitamin B12 production and fermentation of mixed ruminal microorganisms grown in continuous culture flow-through fermentors

    National Research Council Canada - National Science Library

    Tiffany, M. E; Fellner, V; Spears, J. W

    2006-01-01

    ...{at}ncsu.edu An experiment was conducted to determine the effects of dietary concentrations of Co on vitamin B 12 production and fermentation of mixed ruminal microbes grown in continuous culture fermentors...

  8. Effects of partially replacing dietary starch with dry glycerol in a lactating cow diet on ruminal fermentation during continuous culture.

    Science.gov (United States)

    Rico, D E; Chung, Y-H; Martinez, C M; Cassidy, T W; Heyler, K S; Varga, G A

    2012-06-01

    The effects of dry glycerol as a partial replacement for dietary starch in a lactating cow diet on ruminal fermentation and bacterial protein synthesis were evaluated using 4 single-flow, continuous-culture fermentors (ranging from 1,015 to 1,040 mL in volume). The basal lactating cow diet was formulated to have partial contents of dietary starch provided from a corn starch supplement [at 12.37% diet dry matter (DM)], which was partially or completely replaced by a dry glycerol product. Both the corn starch supplement and dry glycerol product contained 65% of pure corn starch or glycerol, respectively. The final inclusion rate for pure glycerol was at 0, 3, 5, or 8% of DM in the basal diet. The experiment was conducted using a 4 × 4 Latin square design with four 9-d periods, with the first 6 d for adaptation and last 3 d for sampling. Fermentors were inoculated with 1L of ruminal fluid and 25 g of ruminal digesta from a ruminally cannulated cow receiving a lactation total mixed ration (16% crude protein, 32% neutral detergent fiber, and 25% starch; DM basis). Each fermentor was fed 75 g of DM of its respective experimental diet daily in 3 equal portions (at 0800, 1400, and 2000 h). Liquid dilution rate of the fermentors was maintained at 10%/h and solids retention time was set at 24 h. Fermentation fluid and the effluent from each fermentor were sampled once daily (at 1330 h) from d 7 to 9 of each period and pooled by period. Postprandial ruminal fermentation was studied by sampling the fermentors hourly for 5 h after the 0800 h feeding on d 9 of each period. The total fermentation contents were harvested at the end of the period for estimations of bacterial protein synthesis. Replacing corn starch with dry glycerol linearly increased the proportions of propionate and valerate at the expense of acetate in the fermentation fluid measured daily or for the first 5h after feeding. Replacing corn starch with dry glycerol also linearly increased the digestibility of

  9. Multi-stage Continuous Culture Fermentation of Glucose-Xylose Mixtures to Fuel Ethanol using Genetically Engineered Saccharomyces cerevisiae 424A

    Science.gov (United States)

    Multi-stage continuous (chemostat) culture fermentation (MCCF) with variable fermentor volumes was carried out to study utilizing glucose and xylose for ethanol production by means of mixed sugar fermentation (MSF). Variable fermentor volumes were used to enable enhanced sugar u...

  10. Effects of Partial Replacement of Corn with Glycerin on Ruminal Fermentation in a Dual-Flow Continuous Culture System.

    Science.gov (United States)

    Del Bianco Benedeti, Pedro; Galoro da Silva, Lorrayny; Marostegan de Paula, Eduardo; Shenkoru, Teshome; Marcondes, Marcos Inácio; Monteiro, Hugo Fernando; Amorati, Brad; Yeh, Yenling; Poulson, Simon Roger; Faciola, Antonio Pinheiro

    2015-01-01

    The objective of this study was to evaluate the effects of partially replacing dry ground corn with glycerin on ruminal fermentation using a dual-flow continuous culture system. Six fermenters (1,223 ± 21 ml) were used in a replicated 3x3 Latin square arrangement with three periods of 10 d each, with 7 d for diet adaptation and 3 d for sample collections. All diets contained 75% concentrate and three dietary glycerin levels (0, 15, and 30% on dry matter basis), totaling six replicates per treatment. Fermenters were fed 72 g of dry matter/d equally divided in two meals/d, at 0800 and 2000 h. Solid and liquid dilution rates were adjusted daily to 5.5 and 11%/h, respectively. On d 8, 9, and 10, samples of 500 ml of solid and liquid digesta effluent were mixed, homogenized, and stored at -20°C. Subsamples of 10 ml were collected and preserved with 0.2 mL of a 50% H2SO4 solution for later determination of NH3-N and volatile fatty acids. Microbial biomass was isolated from fermenters for chemical analysis at the end of each experimental period. Data were analyzed using the MIXED procedure in SAS with α = 0.05. Glycerin levels did not affect apparent digestibility of DM (PLin. = 0.13; PQuad. = 0.40), OM (PLin. = 0.72; PQuad. = 0.15), NDF (PLin. = 0.38; PQuad. = 0.50) and ADF (PLin. = 0.91; PQuad. = 0.18). Also, glycerin inclusion did not affect true digestibility of DM (PLin. = 0.35; PQuad. = 0.48), and OM (PLin. = 0.08; PQuad. = 0.19). Concentrations of propionate (P glycerin inclusion. Linear increases on NH3-N concentration in digesta effluent (P glycerin inclusion in the diets. Crude protein digestibility (P = 0.04) and microbial N flow (P = 0.04) were greater in the control treatment compared with the other treatments and responded quadratically with glycerin inclusion. Furthermore, the inclusion of glycerin linearly decreased (P = 0.02) non-ammonia N flow. Glycerin levels did not affect the flows of total N (PLin. = 0.79; PQuad. = 0.35), and dietary N (PLin. = 0

  11. Simultaneous production and separation of biohydrogen in mixed culture systems by continuous dark fermentation.

    Science.gov (United States)

    Ramírez-Morales, Juan E; Tapia-Venegas, Estela; Toledo-Alarcón, Javiera; Ruiz-Filippi, Gonzalo

    2015-01-01

    Hydrogen production by dark fermentation is one promising technology. However, there are challenges in improving the performance and efficiency of the process. The important factors that must be considered to obtain a suitable process are the source of the inoculum and its pre-treatment, types of substrates, the reactor configurations and the hydrogen partial pressure. Furthermore, to obtain high-quality hydrogen, it is necessary to integrate an effective separation procedure that is compatible with the intrinsic characteristics of a biological process. Recent studies have suggested that a stable and robust process could be established if there was an effective selection of a mixed microbial consortium with metabolic pathways directly targeted to high hydrogen yields. Additionally, the integration of membrane technology for the extraction and separation of the hydrogen produced has advantages for the upgrading step, because this technology could play an important role in reducing the negative effect of the hydrogen partial pressure. Using this technology, it has been possible to implement a production-purification system, the 'hydrogen-extractive membrane bioreactor'. This configuration has great potential for direct applications, such as fuel cells, but studies of new membrane materials, module designs and reactor configurations are required to achieve higher separation efficiencies.

  12. Enteric methane production and ruminal fermentation of forage brassica diets fed in continuous culture

    Science.gov (United States)

    The aim of the current study was to determine nutrient digestibility, VFA production, N metabolism, and CH4 production of canola (Brassica napus L.), rapeseed (B. napus L.), turnip (B. rapa L.), and annual ryegrass (Lolium multiflorum Lam.) fed with orchardgrass (Dactylis glomerata L.) in continuous...

  13. Effect of the combination of crude extracts of Penicillium griseofulvum and Fusarium graminearum containing patulin and zearalenone on rumen microbial fermentation and on their metabolism in continuous culture fermenters.

    Science.gov (United States)

    Riccio, María Belén; Tapia, María Ofelia; Martínez, Guadalupe; Aranguren, Sandra Mariela; Dieguez, Susana Neyi; Soraci, Alejandro Luis; Rodríguez, Edgardo

    2014-01-01

    Six single-flow continuous cultures were used to study the effects of the mycotoxins patulin (PAT) and zearalenone (ZEN) alone or in combination on rumen microbial fermentation. In each of the four 7-d periods, the fermenters were supplemented in a 2 × 3 factorial arrangement with two levels of PAT (0 and 20 mg/l) and three levels of ZEN (0, 5 and 10 mg/l). The treatments did not affect the apparent and true digestibility of organic matter. PAT alone decreased the digestibility of neutral detergent fibre (NDF) and acid detergent fibre (ADF) (p zearalenol and β-zearalenol expressed as a proportion of administered ZEN was less than 50% in effluents from fermenters receiving only ZEN and ZEN plus PAT, respectively. With exception of fibre digestion, the co-administration of PAT and ZEN did not elicit interaction effects on most measured parameters of rumen metabolism.

  14. Starter cultures for kimchi fermentation.

    Science.gov (United States)

    Lee, Mo-Eun; Jang, Ja-Young; Lee, Jong-Hee; Park, Hae-Woong; Choi, Hak-Jong; Kim, Tae-Woon

    2015-05-01

    Kimchi is a traditional Korean vegetable product that is naturally fermented by various microorganisms present in the raw materials. Among these microorganisms, lactic acid bacteria dominate the fermentation process. Natural fermentation with unsterilized raw materials leads to the growth of various lactic acid bacteria, resulting in variations in the taste and quality of kimchi, which may make it difficult to produce industrial-scale kimchi with consistent quality. The use of starter cultures has been considered as an alternative for the industrial production of standardized kimchi, and recent trends suggest that the demand for starter cultures is on the rise. However, several factors should be carefully considered for the successful application of starter cultures for kimchi fermentation. In this review, we summarize recent studies on kimchi starter cultures, describe practical problems in the application of industrial-scale kimchi production, and discuss the directions for further studies.

  15. Effects of flaxseed and chia seed on ruminal fermentation, nutrient digestibility, and long-chain fatty acid flow in a dual-flow continuous culture system.

    Science.gov (United States)

    Silva, L G; Bunkers, J; Paula, E M; Shenkoru, T; Yeh, Y; Amorati, B; Holcombe, D; Faciola, A P

    2016-04-01

    Flaxseed (FS) and chia seed (CS) are oilseeds rich in omega-3 fatty acids, which may change meat and milk composition when added to ruminants' diets and may have health benefits for humans. Literature on the effects of CS supplementation on ruminal metabolism is nonexistent. A dual-flow continuous culture fermenter system consisting of 6 fermenters was used to assess the effect of FS and CS supplementation in an alfalfa hay-based diet on ruminal fermentation, nutrient digestibility, microbial protein synthesis, and long-chain fatty acid flow. Diets were randomly assigned to fermenters in a replicated 3 × 3 Latin square design, with 3 consecutive periods of 10 d each, consisting of 7 d for diet adaptation and 3 d for sample collection. Each fermenter was fed a total of 72 g of DM/d divided in 6 equal portions. Treatments were 1) alfalfa hay + calcium soaps of palm oil fatty acid (MEG; 69.3 g DM/d of alfalfa hay plus 2.7 g DM/d of calcium soaps of palm oil fatty acid), 2) alfalfa hay + FS (FLAX; 68.4 g DM/d of alfalfa hay plus 3.6 g DM/d of ground FS), and 3) alfalfa hay + CS (CHIA; 68.04 g DM/d of alfalfa hay plus 3.96 g DM/d of ground CS). Dietary treatments had similar amounts of total fat, and fat supplements were ground to 2-mm diameter. Effluents from the last 3 d of incubation were composited for analyses. Data were analyzed using the MIXED procedure of SAS. Ruminal apparent and true nutrient digestibility of all nutrients did not differ ( > 0.05) among treatments. Compared with MEG, FLAX and CHIA increased the flows of C18:3 -3, C20:4 -6, and total PUFA ( CHIA and FLAX treatments had greater ruminal concentrations of C18:0, indicating that both CS and FS fatty acids were extensively biohydrogenated in the rumen. The NH-N concentration, microbial N flow, and efficiency of microbial protein synthesis were not affected ( > 0.05) by treatments. Lastly, there were no differences ( > 0.05) among diets for total VFA concentration and molar proportions of individual

  16. Effects of Two Halophytic Plants (Kochia and Atriplex on Digestibility, Fermentation and Protein Synthesis by Ruminal Microbes Maintained in Continuous Culture

    Directory of Open Access Journals (Sweden)

    A. Riasi

    2012-05-01

    Full Text Available Eight continuous culture fermenters were used in a completely randomized design to evaluate various nutritional values of Kochia (Kochia scoparia compared with Atriplex (Atriplex dimorphostegia. Dried and pelleted samples (leaves and stems provided substrate for metabolism by ruminal microbes maintained in a continuous culture fermentation system. Results indicated that there were no differences (p>0.05 in dry matter (DM and crude protein (CP digestibility between the two halophytic plants. Atriplex had higher (p0.05 between the two halophytic plants in molar proportion of acetate and propionate, but the concentration of butyrate and valerate in Kochia were about two fold of Atriplex (p<0.05. When Kochia provided substrate to the microbes, protein synthesis was higher (p<0.05 compared with feeding Atriplex (5.96 vs. 4.85 g N/kg of OM truly digested. It was concluded that Kochia scoparia and Atriplex dimorphostegia had similar digestibility of DM and CP. It appears that these halophytic plants may not have enough digestible energy for high producing ruminants.

  17. Effects of Static or Oscillating Dietary Crude Protein Levels on Fermentation Dynamics of Beef Cattle Diets Using a Dual-Flow Continuous Culture System.

    Directory of Open Access Journals (Sweden)

    Paloma de Melo Amaral

    Full Text Available The objective of this study was to evaluate the effects of increasing dietary crude protein (CP levels and also comparing the effects of static versus oscillating dietary CP on ruminal nutrient digestibility, ruminal fermentation, nitrogen (N metabolism, and microbial efficiency in beef cattle diets using a dual-flow continuous culture system. Eight fermenters (1,223 ± 21 mL were used in a replicated 4 x 4 Latin square design with periods lasting 12 d each (8 d for adaptation and 4 d for sampling. Dietary treatments were: 1 10% CP, 2 12% CP, 3 14% CP, and 4 10 and 14% CP diets oscillating at 48-h intervals. Experimental diets consisted of 50% orchard hay and 50% concentrate. Fermenters were fed 72 g/d and solid and liquid dilution rates were adjusted to 5.5 and 11%/h, respectively. Data were analyzed using the MIXED procedure in SAS with α = 0.05. Apparent and true ruminal digestibilities of dry matter and organic matter were not affected (P > 0.05 by increasing dietary CP, nor by oscillating dietary CP. Total volatile fatty acids concentration and molar proportions of acetate, propionate, butyrate, valerate, iso-butyrate and iso-valerate were not affected (P > 0.05 by increasing or oscillating dietary CP. Ruminal NH3-N concentration increased linearly (P 0.05. However, there was a quadratic effect (P < 0.05 for these variables when dietary CP was increased. These results indicate that either ruminal microorganisms do not respond to oscillating CP levels or are capable of coping with 48-h periods of undernourishment.

  18. In-situ carboxylate recovery and simultaneous pH control with tailor-configured bipolar membrane electrodialysis during continuous mixed culture fermentation

    NARCIS (Netherlands)

    Arslan, D.; Zhang, Y.; Steinbusch, K.J.J.; Diels, L.; Hamelers, Hubertus V.M.; Buisman, C.J.N.; Wever, de H.

    2017-01-01

    Anaerobic fermentation of organic waste streams by mixed culture generates a mixture of short chain carboxylic acids. To avoid inhibitory effects of the acids or their consumption in internal conversion reactions in the mixed culture environment, in-situ recovery of acids can be beneficial. In

  19. In vitro fermentation of NUTRIOSE(® FB06, a wheat dextrin soluble fibre, in a continuous culture human colonic model system.

    Directory of Open Access Journals (Sweden)

    Mark R Hobden

    Full Text Available Wheat dextrin soluble fibre may have metabolic and health benefits, potentially acting via mechanisms governed by the selective modulation of the human gut microbiota. Our aim was to examine the impact of wheat dextrin on the composition and metabolic activity of the gut microbiota. We used a validated in vitro three-stage continuous culture human colonic model (gut model system comprised of vessels simulating anatomical regions of the human colon. To mimic human ingestion, 7 g of wheat dextrin (NUTRIOSE(® FB06 was administered to three gut models, twice daily at 10.00 and 15.00, for a total of 18 days. Samples were collected and analysed for microbial composition and organic acid concentrations by 16S rRNA-based fluorescence in situ hybridisation and gas chromatography approaches, respectively. Wheat dextrin mediated a significant increase in total bacteria in vessels simulating the transverse and distal colon, and a significant increase in key butyrate-producing bacteria Clostridium cluster XIVa and Roseburia genus in all vessels of the gut model. The production of principal short-chain fatty acids, acetate, propionate and butyrate, which have been purported to have protective, trophic and metabolic host benefits, were increased. Specifically, wheat dextrin fermentation had a significant butyrogenic effect in all vessels of the gut model and significantly increased production of acetate (vessels 2 and 3 and propionate (vessel 3, simulating the transverse and distal regions of the human colon, respectively. In conclusion, wheat dextrin NUTRIOSE(® FB06 is selectively fermented in vitro by Clostridium cluster XIVa and Roseburia genus and beneficially alters the metabolic profile of the human gut microbiota.

  20. Effect of corn inclusion on soybean hull-based diet digestibility and growth performance in continuous culture fermenters and beef cattle.

    Science.gov (United States)

    Russell, J R; Sexten, W J; Kerley, M S

    2016-07-01

    Two experiments were conducted using soybean hull (SH) diets with increasing corn proportions to determine increasing corn inclusion effects on fermentation characteristics, diet digestibility, and feedlot performance. The hypothesis was that fiber digestibility would quadratically respond to starch proportion in the diet with a break point where starch inclusion improved fiber digestion and feedlot performance. Proportionately, the diets contained 100:0 (SH100), 90:10 (SH90), 80:20 (SH80), 60:40 (SH60), or 20:80 SH:corn (SH20). In Exp. 1, diets were randomly distributed over 24 continuous culture fermenters and fed for 7 d. In Exp. 2, forty steers (347 ± 29 kg BW) and 50 heifers (374 ± 24 kg BW) were blocked by gender, stratified by BW, and distributed across diets. Cattle were fed for 70 d with titanium dioxide included in the diet for the final 14 d and fecal samples collected to measure digestibility. Individual DMI was measured using GrowSafe Feed Intake system. Data were analyzed using the MIXED procedure of SAS with diet evaluated as the fixed effect. In Exp. 1, NDF digestibility (NDFd) linearly decreased ( = 0.04) and ADF digestibility (ADFd) tended to linearly decrease ( = 0.09) as corn increased. Dry matter digestibility (DMd) was cubic ( = 0.01) and OM digestibility (OMd) was quadratic ( = 0.03), and among the 4 SH-based diets, DMd and OMd were greatest for SH90. Acetate:propionate ratio and pH were quadratic ( diets, ADG was numerically greatest for SH80. There was no DMI difference ( ≥ 0.4) due to diet. As corn inclusion increased, DMd tended to linearly increase (P = 0.06), as did OMd ( = 0.05). Both NDFd and ADFd were quadratic ( = 0.04) and greatest for SH80. Overall, feedlot performance increased and fiber digestibility decreased as corn inclusion increased. However, based on continuous culture digestibility and VFA values as well as feedlot digestibility and performance, optimal corn inclusion for growth and diet utilization in the 4 SH

  1. Integrative modelling of pH-dependent enzyme activity and transcriptomic regulation of the acetone–butanol–ethanol fermentation of Clostridium acetobutylicum in continuous culture

    Science.gov (United States)

    Millat, Thomas; Janssen, Holger; Bahl, Hubert; Fischer, Ralf-Jörg; Wolkenhauer, Olaf

    2013-01-01

    Summary In a continuous culture under phosphate limitation the metabolism of Clostridium acetobutylicum depends on the external pH level. By comparing seven steady-state conditions between pH 5.7 and pH 4.5 we show that the switch from acidogenesis to solventogenesis occurs between pH 5.3 and pH 5.0 with an intermediate state at pH 5.1. Here, an integrative study is presented investigating how a changing external pH level affects the clostridial acetone–butanol–ethanol (ABE) fermentation pathway. This is of particular interest as the biotechnological production of n-butanol as biofuel has recently returned into the focus of industrial applications. One prerequisite is the furthering of the knowledge of the factors determining the solvent production and their integrative regulations. We have mathematically analysed the influence of pH-dependent specific enzyme activities of branch points of the metabolism on the product formation. This kinetic regulation was compared with transcriptomic regulation regarding gene transcription and the proteomic profile. Furthermore, both regulatory mechanisms were combined yielding a detailed projection of their individual and joint effects on the product formation. The resulting model represents an important platform for future developments of industrial butanol production based on C. acetobutylicum. PMID:23332010

  2. Continuous cultures of phytoplankton

    National Research Council Canada - National Science Library

    Baron, Ron; Davie, Alexander; Gaines, Alec; Grant, Darren; Okay, Oya; Ozsoy, Emin

    2014-01-01

    The development of cultures of phytoplankton adapting throughout several days in an axenic, continuous-flow chemostat to yield a steady kinetic state of competing species is described mathematically...

  3. Continuous fermentation and stripping of ethanol.

    Science.gov (United States)

    Taylor, F; Kurantz, M J; Goldberg, N; Craig, J C

    1995-01-01

    Recycling the contents of a continuous fermentor through a stripping column is proposed as a means of reducing product inhibition and lowering the cost of fuel ethanol production. A 2-L fermentor and 10-cm packed column were continuously operated for 150 days without contamination. Some fouling of the packing with attached yeast cells was observed which partially blocked the column. Cell yield was lower than in a simple continuous fermentor. Complete conversion of 200 g/L glucose feed and 90% conversion of 600 g/L glucose feed were achieved. Data were analyzed by computerized process simulation. Cost analysis indicated that, with heat recovery to reduce heating and cooling costs, the continuous fermentor/stripper is possibly a lower-cost alternative to conventional fermentation and distillation.

  4. Effect of dilution rate and nutrients addition on the fermentative capability and synthesis of aromatic compounds of two indigenous strains of Saccharomyces cerevisiae in continuous cultures fed with Agave tequilana juice.

    Science.gov (United States)

    Morán-Marroquín, G A; Córdova, J; Valle-Rodríguez, J O; Estarrón-Espinosa, M; Díaz-Montaño, D M

    2011-11-15

    Knowledge of physiological behavior of indigenous tequila yeast used in fermentation process is still limited. Yeasts have significant impact on the productivity fermentation process as well as the sensorial characteristics of the alcoholic beverage. For these reasons a better knowledge of the physiological and metabolic features of these yeasts is required. The effects of dilution rate, nitrogen and phosphorus source addition and micro-aeration on growth, fermentation and synthesis of volatile compounds of two native Saccharomyces cerevisiae strains, cultured in continuous fed with Agave tequilana juice were studied. For S1 and S2 strains, maximal concentrations of biomass, ethanol, consumed sugars, alcohols and esters were obtained at 0.04 h⁻¹. Those concentrations quickly decreased as D increased. For S. cerevisiae S1 cultures (at D=0.08 h⁻¹) supplemented with ammonium phosphate (AP) from 1 to 4 g/L, concentrations of residual sugars decreased from 29.42 to 17.60 g/L and ethanol increased from 29.63 to 40.08 g/L, respectively. The S1 culture supplemented with AP was then micro-aerated from 0 to 0.02 vvm, improving all the kinetics parameters: biomass, ethanol and glycerol concentrations increased from 5.66, 40.08 and 3.11 g/L to 8.04, 45.91 and 4.88 g/L; residual sugars decreased from 17.67 g/L to 4.48 g/L; and rates of productions of biomass and ethanol, and consumption of sugars increased from 0.45, 3.21 and 7.33 g/L·h to 0.64, 3.67 and 8.38 g/L·h, respectively. Concentrations of volatile compounds were also influenced by the micro-aeration rate. Ester and alcohol concentrations were higher, in none aerated and in aerated cultures respectively. Copyright © 2011. Published by Elsevier B.V.

  5. Modification of ruminal fermentation and methane production by adding legumes containing condensed tannins to an orchardgrass diet in continuous culture systems

    Science.gov (United States)

    Condensed tannins (CT) can alter ruminal fermentation and enteric methane (CH4) production in ruminants; however, research is lacking on how increased CT levels affect nutrient digestibility, volatile fatty acid (VFA) production, bacterial protein synthesis, fatty acid (FA) profiles, protozoal popul...

  6. Hydrogen as clean fuel via continuous fermentation by anaerobic ...

    African Journals Online (AJOL)

    free and oxidized to water as a combustion product. Bioconversion of synthesis gas to hydrogen was demonstrated in a continuous fermentation utilizing malate as a carbon source. Rhodospirillum rubrum, an anaerobic photosynthetic bacterium ...

  7. Use of a continuous multistage bioreactor to mimic winemaking fermentation.

    Science.gov (United States)

    Clement, T; Perez, M; Mouret, J R; Sablayrolles, J M; Camarasa, C

    2011-10-17

    Continuous fermentation set-ups are of great interest for studying the physiology of microorganisms. In winemaking conditions, yeasts go through a growth phase and a stationary phase during which more than half of the sugar is fermented. A comprehensive study of wine-yeast physiology must therefore include yeasts in a non-growing phase. This condition is impossible to achieve within a chemostat, which led us to design a multi-stage fermentation device. In this study, we evaluated the ability of such a device to reproduce, in a series of steady states, the conditions of batch fermentation. Two-stage and four-stage fermentations were carried out with two different strains of Saccharomyces cerevisiae. The main characteristics of the fermentation process (biomass growth, by-product content of the medium) were compared with those observed in batch mode at the same stage of fermentation, which was defined by glucose uptake. The four-stage configuration showed a better ability to reproduce batch fermentation characteristics than the two-stage set-up. It also allowed to uncouple the variations of environmental parameters and proved to be a promising tool to gain new insights into yeast metabolism during alcoholic fermentation. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. A review of flavour formation in continuous beer fermentations

    OpenAIRE

    Brányik, Tomáš; Vicente, A. A.; Dostálek, Pavel; Teixeira, J. A.

    2008-01-01

    The attractive prospect of a continuous beer fermentation system consists mostly of the accelerated transformation of wort into beer. Although continuous beer fermentation has been studied as a promising technology for several decades, the number of industrial applications is still limited. The major obstacle hindering the extensive industrial exploitation of this technology is the difficulty in achieving the correct balance of sensory compounds in the short time typical ...

  9. Effect of pH, aeration and feeding non-sterilized agave juice in a continuous agave juice fermentation.

    Science.gov (United States)

    Hernández-Cortés, Guillermo; Córdova-López, Jesús A; Herrera-López, Enrique J; Morán-Marroquín, Gabriel A; Valle-Rodríguez, Juan O; Díaz-Montaño, Dulce M

    2010-07-01

    Continuous cultures have been used since the 1950s in beer and wine fermentations due to their higher productivities compared to traditional batch systems; nevertheless, the tequila industry has not taken advantage of the possible improvements that continuous fermentations could offer. In this work, the effect of pH, aeration and feeding of non-sterilized medium, on the fermentative capability of two Saccharomyces cerevisiae strains (S1 and S2) cultured in continuous fermentation, using agave juice as the fermentation medium, were studied. In continuous cultures, the control of the medium pH (set point at 4) did not have a significant effect on fermentation efficiency compared to fermentations in which the pH was not controlled (pH 2.5 +/- 0.3). Conversely, aeration of the cultures of both strains improved biomass production and consumption of reducing sugars and ammonium. The aeration also significantly augmented ethanol production only for S1 cultures (P sterilized or not, did not show significant differences on the production of ethanol for S1 cultures. Higher concentrations of acetoin, succinic acid and diacetyl were found in the cultures fed with non-sterilized medium. Compared to S2, S1 has a better fermentative performance in continuous non-sterilized medium fermentations. Not controlling the pH during the cultures could prevent the possibility of microbial contamination as a result of the extreme medium acidity (pH 2.5 +/- 0.3). This work showed the possibility of scaling up agave juice continuous fermentation feeding non-sterilized medium with no control of pH.

  10. Simulation and optimization of continuous extractive fermentation with recycle system

    Science.gov (United States)

    Widjaja, Tri; Altway, Ali; Rofiqah, Umi; Airlangga, Bramantyo

    2017-05-01

    Extractive fermentation is continuous fermentation method which is believed to be able to substitute conventional fermentation method (batch). The recovery system and ethanol refinery will be easier. Continuous process of fermentation will make the productivity increase although the unconverted sugar in continuous fermentation is still in high concentration. In order to make this process more efficient, the recycle process was used. Increasing recycle flow will enhance the probability of sugar to be re-fermented. However, this will make ethanol enter fermentation column. As a result, the accumulated ethanol will inhibit the growth of microorganism. This research aims to find optimum conditions of solvent to broth ratio (S:B) and recycle flow to fresh feed ratio in order to produce the best yield and productivity. This study employed optimization by Hooke Jeeves method using Matlab 7.8 software. The result indicated that optimum condition occured in S: B=2.615 and R: F=1.495 with yield = 50.2439 %.

  11. Fermentation capacity of Saccharomyces cerevisiae cultures

    Directory of Open Access Journals (Sweden)

    Elvira Maria Bezerra de Alencar

    2009-08-01

    Full Text Available This work aimed at the assessment of fermentative capacity of original diploid, monocellular haploid and recuperated diploid cultures of S. cerevisiae in sterilized sugar-cane wort. Twenty eight cultures were analyzed, four being original diploids (URM-4420, Itaiquara Ferment FIT, Lallemand Ferment FLA and Wild Ferment SEL; 12 monocellular haploids from original ones and 12 recuperated diploids from the monocells. The ethanol percentage ranged from 1.7 to 6.2% and the unfermentable reducing sugars from 0.45 to 0.50g/100mL. The highest ethanol percentages were produced by the monocellular cultures URM-MH3 (4.8% in 12 h and SEL-MH1 (6.2% in 24 h, corresponding to the productivity values of 3.15 and 2.03 g.L-1.h-1, respectively. The recuperated diploids did not present detectable ethanol content by the method used. The results showed that depending on the physiological state of the yeasts, being in the diploid or monocellular haploid form, different percentages of ethanol could be produced.Este trabalho teve como objetivo avaliar culturas de S. cerevisiae diplóides originais, haplóides monocelulares e diplóides recuperados, quanto à capacidade de fermentar em mosto de cana-deaçúcar esterilizado. Vinte e oito culturas foram analisadas, sendo 4 diplóides originais (URM-4420, Fermento Itaiquara FIT, Fermento Lallemand FLA e Fermento Selvagem SEL; 12 haplóides monocelulares provenientes das originais e 12 diplóides recuperados a partir das monocelulares. O percentual de etanol produzido variou de 1,70% a 6,20% e os açúcares redutores infermentescíveis de 0,45 g/100mL a 0,50 g/100mL. Os maiores percentuais de etanol foram produzidos pelas culturas haplóides monocelulares URM-MH3 (4,80%, em 12 horas e SEL-MH1 (6,20%, em 24 horas, correspondendo a valores de produtividade 3,15g.L-1.h-1 e 2,03 g.L-1.h-1 , respectivamente. Os diplóides recuperados não apresentaram teores de etanol detectáveis pelo método utilizado. Os resultados mostram que

  12. The Effect of Autochthonous Starter Culture, Sugars and Temperature on the Fermentation of Slavonian Kulen

    Directory of Open Access Journals (Sweden)

    Krešimir Mastanjević

    2017-01-01

    Full Text Available In this study, the effect of an isolated and well-characterised autochthonous starter culture, glucose and maltodextrin (w=0.8 % and temperatures of 12 and 20 °C on fermentation and quality of Slavonian kulen produced using the traditional technology and recipe were investigated. Physicochemical and microbiological analyses were carried out after 20 days of fermentation. Upon the completion of the production process (90 days, a sensory analysis was carried out. Furthermore, pH value was continuously measured throughout the twenty-day fermentation period. The addition of an autochthonous starter culture and sugars and diff erent fermentation temperatures significantly (p<0.05 affected the instrumental colour and texture parameters of the Slavonian kulen. The fermentation was most intense in the samples with added autochthonous starter culture and 0.8 % glucose, and fermented at 20 °C. Microbiological analysis showed that samples with added autochthonous starter culture and fermented at higher temperature contained a higher number of lactic acid bacteria and coagulase-negative staphylococci and were safe. Sensory evaluation confirmed the outcomes of physicochemical and microbiological analyses and showed differences among samples fermented at two different temperatures and with added glucose or maltodextrin and an autochthonous starter culture.

  13. Model based Control of a Continuous Yeast Fermentation

    DEFF Research Database (Denmark)

    Andersen, Maria Yolanda; Brabrand, Henrik; Jørgensen, Sten Bay

    1991-01-01

    Control of a continuous fermentation with Saccharomyces cerevisiae is performed by manipulation of the feed flow rate using an ethanol measurement in the exit gas The process is controlled at the critical dilution rate with a low ethanol concentration of 40-50 mg/l. A standard PI controller is able...

  14. EFFECT OF FERMENTATION BY MIXED CULTURES OF LACTIC ...

    African Journals Online (AJOL)

    ABSTRACT: Tef atmit (thin gruel) was fermented by mixed cultures of lactic acid bacteria (LAB), namely, Lactobacillus casei, Lactobacillus plantarum,. Lactobacillusfermentum and Pediococcus pentasaceus, at 30° C for 2 days. The fermentation brought about a significant increase in inorganic phosphorus, and.

  15. Anaerobic Membrane Bioreactor for Continuous Lactic Acid Fermentation

    Science.gov (United States)

    Fan, Rong; Ebrahimi, Mehrdad; Czermak, Peter

    2017-01-01

    Membrane bioreactor systems can enhance anaerobic lactic acid fermentation by reducing product inhibition, thus increasing productivity. In batch fermentations, the bioconversion of glucose is strongly inhibited in the presence of more than 100 g·L−1 lactic acid and is only possible when the product is simultaneously removed, which can be achieved by ceramic membrane filtration. The crossflow velocity is a more important determinant of flux than the transmembrane pressure. Therefore, to stabilize the performance of the membrane bioreactor system during continuous fermentation, the crossflow velocity was controlled by varying the biomass concentration, which was monitored in real-time using an optical sensor. Continuous fermentation under these conditions, thus, achieved a stable productivity of ~8 g·L−1·h−1 and the concentration of lactic acid was maintained at ~40 g·L−1 at a dilution rate of 0.2 h−1. No residual sugar was detected in the steady state with a feed concentration of 50 g·L−1. PMID:28467384

  16. Continuous beer fermentation using immobilized yeast cell bioreactor systems.

    Science.gov (United States)

    Brányik, Tomás; Vicente, António A; Dostálek, Pavel; Teixeira, José A

    2005-01-01

    Traditional beer fermentation and maturation processes use open fermentation and lager tanks. Although these vessels had previously been considered indispensable, during the past decades they were in many breweries replaced by large production units (cylindroconical tanks). These have proved to be successful, both providing operating advantages and ensuring the quality of the final beer. Another promising contemporary technology, namely, continuous beer fermentation using immobilized brewing yeast, by contrast, has found only a limited number of industrial applications. Continuous fermentation systems based on immobilized cell technology, albeit initially successful, were condemned to failure for several reasons. These include engineering problems (excess biomass and problems with CO(2) removal, optimization of operating conditions, clogging and channeling of the reactor), unbalanced beer flavor (altered cell physiology, cell aging), and unrealized cost advantages (carrier price, complex and unstable operation). However, recent development in reactor design and understanding of immobilized cell physiology, together with application of novel carrier materials, could provide a new stimulus to both research and application of this promising technology.

  17. Nonlinear analysis and control of a continuous fermentation process

    DEFF Research Database (Denmark)

    Szederkényi, G.; Kristensen, Niels Rode; Hangos, K.M

    2002-01-01

    Different types of nonlinear controllers are designed and compared for a simple continuous bioreactor operating near optimal productivity. This operating point is located close to a fold bifurcation point. Nonlinear analysis of stability, controllability and zero dynamics is used to investigate o...... are recommended for the simple fermenter. Passivity based controllers have been found to be globally stable, not very sensitive to the uncertainties in the reaction rate and controller parameter but they require full nonlinear state feedback....

  18. The microbiology of Ghanaian cocoa fermentations analysed using culture-dependent and culture-independent methods.

    Science.gov (United States)

    Nielsen, D S; Teniola, O D; Ban-Koffi, L; Owusu, M; Andersson, T S; Holzapfel, W H

    2007-03-10

    Export of cocoa beans is of great economic importance in Ghana and several other tropical countries. Raw cocoa has an astringent unpleasant taste and a spontaneous fermentation is the first step in a process leading to cocoa beans with the characteristic cocoa flavour and taste. The microbiology of Ghanaian cocoa fermentations was investigated using culture-dependent and culture-independent methods. Samples were collected at 12 hour intervals during 96-144 hour tray and traditional heap fermentations. Yeast, Lactic Acid Bacteria (LAB), Acetic Acid Bacteria (AAB) and Bacillus spp. were enumerated on suitable substrates and identified using phenotypic and molecular methods. The yeast and bacterial micro-populations involved in the cocoa fermentation were further investigated using the culture-independent method Denaturing Gradient Gel Electrophopresis (DGGE). A microbiological succession was observed during the fermentations. At the onset of fermentation yeasts were the dominating microorganisms. Lactic Acid Bacteria became dominant after 12-24 h of fermentation and remained predominant throughout the fermentations with AAB reaching high counts in the mid phase of fermentation. Bacillus spp. were only detected during heap fermentations where they reached high numbers during the later stages of fermentation. Hanseniaspora guilliermondii was the predominant yeast during the initial phase and Pichia membranifaciens during the later phases of fermentation. A number of other yeast species including three putatively undescribed species were isolated during the fermentations. Lactobacillus fermentum was the dominant LAB in most samples. Several other LAB including Lactobacillus plantarum, Leuconostoc pseudomesenteroides, Leuconostoc pseudoficulneum, Pediocococcus acidilactici and a putatively undescribed LAB species were detected during the fermentations. Acetobacter syzygii, Acetobacter pasteurianus and Acetobacter tropicalis were the predominant AAB in all investigated

  19. Process for producing fuel grade ethanol by continuous fermentation, solvent extraction and alcohol separation

    Science.gov (United States)

    Tedder, Daniel W.

    1985-05-14

    Alcohol substantially free of water is prepared by continuously fermenting a fermentable biomass feedstock in a fermentation unit, thereby forming an aqueous fermentation liquor containing alcohol and microorganisms. Continuously extracting a portion of alcohol from said fermentation liquor with an organic solvent system containing an extractant for said alcohol, thereby forming an alcohol-organic solvent extract phase and an aqueous raffinate. Said alcohol is separated from said alcohol-organic solvent phase. A raffinate comprising microorganisms and unextracted alcohol is returned to the fermentation unit.

  20. Development of a goat fermented milk with probiotics starter culture

    Directory of Open Access Journals (Sweden)

    Aldo Hernández-Monzón

    2016-07-01

    Full Text Available The goat milk for their multiple properties nutraceutical and for the high yield of their derived products, it represents an interesting commercial alternative for the elaboration of special fermented milk. At the present time the probiotics starter culture for their proven properties are used thoroughly in the elaboration of fermented milk. Keeping in mind these antecedents this work had as objective to develop a fermented milk of goat with characteristic probiotics, good acceptability and appropriate shelf life using the starter culture Lactobacillus casei, Lactobacillus acidophilus jointly with the starter culture of the yogurt. It was carried out a design of experiment of response surface (22 with the independent variables, starter culture dose (1.5 to 2.5% and the relationship of starter culture of yogurt: probiotics starter culture 1:3 at 1:5. As variable answers they took: the viability, the acidity and the sensorial indicators. The formulation selected with the best characteristics was conserved to temperature of 4 oC for the evaluation of the storage life. The best formulation was the 2% starter culture with a relationship of 1:4. The fermented milk was evaluated of “I like” and its viability was above the therapeutic minimum until the 21 days (log (UFC/ml of 8.8 at 7.0.

  1. Optimization of asparaginase production from Zymomonas mobilis by continuous fermentation

    Directory of Open Access Journals (Sweden)

    Francieli Bortoluzzi Menegat

    2016-10-01

    Full Text Available Asparaginase is an enzyme used in clinical treatments as a chemotherapeutic agent and in food technology to prevent acrylamide formation in fried and baked foods. Asparaginase is industrially produced by microorganisms, mainly gram-negative bacteria. Zymomonas mobilis is a Gram-negative bacterium that utilizes glucose, fructose and sucrose as carbon source and has been known for its efficiency in producing ethanol, sorbitol, levan, gluconic acid and has recently aroused interest for asparaginase production. Current assay optimizes the production of Z. mobilis asparaginase by continuous fermentation using response surface experimental design and methodology. The studied variables comprised sucrose, yeast extract and asparagine. Optimized condition obtained 117.45 IU L-1 with dilution rate 0.20 h-1, yeast extract 0.5 g L-1, sucrose 20 g L-1 and asparagine 1.3 g L-1. Moreover, carbon:nitrogen ratio (1:0.025 strongly affected the response of asparaginase activity. The use of Z. mobilis by continuous fermentation has proved to be a promising alternative for the biotechnological production of asparaginase.

  2. Continuous dry fermentation of swine manure for biogas production

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chuang; Zheng, Dan [Biogas Institute of Ministry of Agriculture, Chengdu 610041 (China); Liu, Gang–Jin [Biogas Institute of Ministry of Agriculture, Chengdu 610041 (China); Bioprocess Control AB, Scheelevägen 22, 223 63 Lund (Sweden); Deng, Liang–Wei, E-mail: dengliangwei@caas.cn [Biogas Institute of Ministry of Agriculture, Chengdu 610041 (China); Laboratory of Development and Application of Rural Renewable Energy, Ministry of Agriculture, Chengdu 610041 (China); Southwest Collaborative Innovation Center of Swine for Quality & Safety, Chengdu 611130 (China); Long, Yan; Fan, Zhan–Hui [Biogas Institute of Ministry of Agriculture, Chengdu 610041 (China)

    2015-04-15

    Highlights: • Continuous dry fermentation of swine manure for biogas production is feasible. • The feedstock TS concentration exerted a significant impact on biogas production. • Influences of ammonia and digestate liquidity were investigated in this study. • The results showed that the feedstock TS of swine manure should not exceed 30%. - Abstract: A down plug-flow anaerobic reactor (DPAR) was designed for the feasibility study on continuous dry fermentation of swine manure without any additional stirring. Using fresh swine manure as the feedstock with TS concentration (w/w) of 20%, 25%, 30%, and 35%, stable volumetric biogas production rates of 2.40, 1.92, 0.911, and 0.644 L·(L d){sup −1} and biogas yields of 0.665, 0.532, 0.252, and 0.178 L g{sup −1}VS were obtained respectively, and the TS degradation rates were 46.5%, 45.4%, 53.2%, and 55.6%, respectively. With the increase of feedstock TS concentration, the concentration of ammonia nitrogen grew up to the maximum value of 3500 mg L{sup −1}. Biogas production was obviously inhibited when the concentration of ammonia nitrogen was above 3000 mg L{sup −1}. The maximal volumetric biogas production rate of 2.34 L·(L d){sup −1} and biogas yield of 0.649 L g{sup −1}VS were obtained with TS concentration of 25% at 25 °C without inhibition. Liquidity experiments showed that TS concentration of digestate could be less than 15.8%, and the flow rate of digestate more than 0.98 m s{sup −1} when the feedstock TS concentration was less than 35%, which indicated the digestate could be easily discharged from a DPAR. Therefore, it is feasible to conduct a continuous dry fermentation in a DPAR using fresh swine manure as the feedstock with TS concentration less than 35%, whereas the feedstock TS concentration should not exceed 30% to achieve the maximal biogas production rate and biogas yield.

  3. Table Olive Fermentation Using Starter Cultures with Multifunctional Potential

    Directory of Open Access Journals (Sweden)

    Stamatoula Bonatsou

    2017-05-01

    Full Text Available Table olives are one of the most popular plant-derived fermented products. Their enhanced nutritional value due to the presence of phenolic compounds and monounsaturated fatty acids makes olives an important food commodity of the Mediterranean diet. However, despite its economic significance, table olive fermentation is mainly craft-based and empirically driven by the autochthonous microbiota of the olives depending on various intrinsic and extrinsic factors, leading to a spontaneous process and a final product of variable quality. The use of microorganisms previously isolated from olive fermentations and studied for their probiotic potential and technological characteristics as starter cultures may contribute to the reduction of spoilage risk resulting in a controlled fermentation process. This review focuses on the importance of the development and implementation of multifunctional starter cultures related to olives with desirable probiotic and technological characteristics for possible application on table olive fermentation with the main purpose being the production of a health promoting and sensory improved functional food.

  4. Table Olive Fermentation Using Starter Cultures with Multifunctional Potential

    Science.gov (United States)

    Bonatsou, Stamatoula; Tassou, Chrysoula C.; Panagou, Efstathios Z.; Nychas, George-John E.

    2017-01-01

    Table olives are one of the most popular plant-derived fermented products. Their enhanced nutritional value due to the presence of phenolic compounds and monounsaturated fatty acids makes olives an important food commodity of the Mediterranean diet. However, despite its economic significance, table olive fermentation is mainly craft-based and empirically driven by the autochthonous microbiota of the olives depending on various intrinsic and extrinsic factors, leading to a spontaneous process and a final product of variable quality. The use of microorganisms previously isolated from olive fermentations and studied for their probiotic potential and technological characteristics as starter cultures may contribute to the reduction of spoilage risk resulting in a controlled fermentation process. This review focuses on the importance of the development and implementation of multifunctional starter cultures related to olives with desirable probiotic and technological characteristics for possible application on table olive fermentation with the main purpose being the production of a health promoting and sensory improved functional food. PMID:28555038

  5. Continuous dry fermentation of swine manure for biogas production.

    Science.gov (United States)

    Chen, Chuang; Zheng, Dan; Liu, Gang-Jin; Deng, Liang-Wei; Long, Yan; Fan, Zhan-Hui

    2015-04-01

    A down plug-flow anaerobic reactor (DPAR) was designed for the feasibility study on continuous dry fermentation of swine manure without any additional stirring. Using fresh swine manure as the feedstock with TS concentration (w/w) of 20%, 25%, 30%, and 35%, stable volumetric biogas production rates of 2.40, 1.92, 0.911, and 0.644L · (Ld)(-1) and biogas yields of 0.665, 0.532, 0.252, and 0.178 L g(-)(1)VS were obtained respectively, and the TS degradation rates were 46.5%, 45.4%, 53.2%, and 55.6%, respectively. With the increase of feedstock TS concentration, the concentration of ammonia nitrogen grew up to the maximum value of 3500 mg L(-1). Biogas production was obviously inhibited when the concentration of ammonia nitrogen was above 3000 mg L(-1). The maximal volumetric biogas production rate of 2.34 L ·(Ld)(-1) and biogas yield of 0.649 L g(-1)VS were obtained with TS concentration of 25% at 25°C without inhibition. Liquidity experiments showed that TS concentration of digestate could be less than 15.8%, and the flow rate of digestate more than 0.98 m s(-1) when the feedstock TS concentration was less than 35%, which indicated the digestate could be easily discharged from a DPAR. Therefore, it is feasible to conduct a continuous dry fermentation in a DPAR using fresh swine manure as the feedstock with TS concentration less than 35%, whereas the feedstock TS concentration should not exceed 30% to achieve the maximal biogas production rate and biogas yield. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Synergistic dark and photo-fermentation continuous system for hydrogen production from molasses by Clostridium acetobutylicum ATCC 824 and Rhodobacter capsulatus DSM 1710.

    Science.gov (United States)

    Morsy, Fatthy Mohamed

    2017-04-01

    This study investigated synergistic dark and photo-fermentation using continuous fermentation system (CFS). The system relies on connecting several fermenters from bottom of one to top culture level of the next in a manner that allows for delaying movement of the substrate and thus for its full consumption. While H 2 was collected, CFS allowed for moving liquid byproducts toward the outlet and hence continuous productivity. CFS could be efficiently used for: (1) Continuous dark and photo-fermentation H 2 production by Clostridium acetobutylicum and Rhodobacter capsulatus producing 5.65moleH 2 mole -1 hexose; (2) Continuous dark-fermentation synergistic H 2 , acetone, butanol and ethanol (ABE) production by C. acetobutylicum which produced per mole hexose, 2.43mol H 2 along with 73.08g ABE (3) Continuous H 2 and methane production by C. acetobutylicum and bacterial sludge producing, per mole hexose, 1.64mol pure H 2 and 2.56mol CH 4 mixed with 0.37mol H 2 ·The hydraulic retention time (HRT) for whole system was short where organic acids produced in dark-fermentation in first fermenter were synergistically utilized for H 2 production by R. capsulatus in subsequent fermenters. CFS is suitable for fast-digestible sugars but not lignocelluloses or other hard-digestible organics, requiring prolonged HRT, unless such polymeric organics were hydrolyzed prior to fermentation. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Use of Protein Hydrolysates in Industrial Starter Culture Fermentations

    Science.gov (United States)

    Ummadi, Madhavi (Soni); Curic-Bawden, Mirjana

    Lactic acid bacteria (LAB) have been used as starter cultures for fermenting foods long before the importance of microorganisms were recognized. The most important group of LAB are the lactococci, lactobacilli, streptococci, and pediococci. Additionally, bifidobacteria have been included as a probiotic, providing added value to the product. Since the genera involved are so diverse, the nutritional requirements (energy, carbon and nitrogen sources) differ significantly between and within species. Designing an optimum fermentation medium for production of active and vigorous LAB starter cultures and probiotics requires selecting the right raw ingredients, especially protein hydrolysates that can provide adequate nutrients for growth and viability. This chapter attempts to describe the application of various commercial protein hydrolysates used for production of dairy and meat starter cultures, with special emphasis on meeting the nitrogen requirements of industrially important LAB species.

  8. Probiotic culture survival and implications in fermented frozen yogurt characteristics.

    Science.gov (United States)

    Davidson, R H; Duncan, S E; Hackney, C R; Eigel, W N; Boling, J W

    2000-04-01

    Low-fat ice cream mix was fermented with probiotic-supplemented and traditional starter culture systems and evaluated for culture survival, composition, and sensory characteristics of frozen product. Fermentations were stopped when the titratable acidity reached 0.15% greater than the initial titratable acidity (end point 1) or when the pH reached 5.6 (end point 2). Mix was frozen and stored for 11 wk at -20 degrees C. The traditional yogurt culture system contained the strains Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. The probiotic-supplemented system contained the traditional cultures as well as Bifidobacterium longum and Lactobacillus acidophilus. We compared recovery of Bifodobacterium by three methods, a repair-detection system with roll-tubes and plates on modified bifid glucose medium and plates with maltose + galactose reinforced clostridial medium. Culture bacteria in both systems did not decrease in the yogurt during frozen storage. The roll-tube method with modified bifid glucose agar and repair detection system provided at least one-half log10 cfu/ml higher recovery of B. longum compared with recoveries using modified bifid glucose agar or maltose + galactose reinforced clostridial agar on petri plates. No change in concentrations of lactose or protein for products fermented with either culture system occurred during storage. Acid flavor was more intense when product was fermented to pH 5.6, but yogurt flavor was not intensified. The presence of probiotic bacteria in the supplemented system seemed to cause no differences in protein and lactose concentration and sensory characteristics.

  9. Antioxidant activity of fermented broccoli and spinach by Kombucha culture

    Science.gov (United States)

    Artanti, Nina; Susilowati, Agustine; Aspiyanto, Lotulung, Puspa Dewi Narrij; Maryati, Yati

    2017-11-01

    Broccoli (Brassica oleracea L.) and spinach (Amaranthus spp.) are vegetables that known to have many benefit for health. Previous studies on the fermentation of those vegetables using kombucha cultured showed increase in bioactive components such as total polyphenol content. The current studies was performed to evaluate the antioxidant activity of fermented spinach and broccoli before (feed) and after treatment with filtration (retentate and permeate). Filtration was conducted using Stirred Ultrafiltration Cell (SUFC) with UF membrane 100,000 MWCO mode at fixed condition (stirred rotation 300 rpm, room temperature, pressure 40 psia). Antioxidant evaluation was conducted using 2,2-diphenyl-1-picril hydrazyl (DPPH) free radical scavenging activity assay. The results showed that all samples from fermented broccoli showed antioxidant activity (feed 15.82% inhibition and retentate 15.29% inhibition), with the best antioxidant activity was obtained from permeate (75.98% inhibition). Whereas from fermented spinach only permeate showed antioxidant activity (21.84% inhibition) and it significantly lower than broccoli permeate. The mass spectrum of LCMS analysis on broccoli samples showed the present of several mass spectrum with (M+H) range from 148.1 to 442.5 in feed, retentate and permeate. In those samples (M+H) 360.4 always has the highest relative intensity. These results suggest that fermented broccoli has potential for development as functional drink for the source of antioxidant and the permeate obtained from filtration treatment significantly increased the antioxidant activity.

  10. Cultural Continuities: An Australian Perspective.

    Science.gov (United States)

    Ebbeck, Marjory

    2001-01-01

    Examined school attitudes of 101 mothers of preschoolers who were immigrants to Australia from Vietnam, Cambodia, Indonesia, mainland China, and the Philippines; also examined views of 100 early childhood teachers. Found differences in views regarding the importance of maintaining family culture and first language, and the importance of sharing…

  11. Dark fermentation on biohydrogen production: Pure culture.

    Science.gov (United States)

    Lee, Duu-Jong; Show, Kuan-Yeow; Su, Ay

    2011-09-01

    Biohydrogen is regarded as an attractive future clean energy carrier due to its high energy content and environmental-friendly conversion. While biohydrogen production is still in the early stage of development, there have been a variety of laboratory- and pilot-scale systems developed with promising potential. This work presents a review of literature reports on the pure hydrogen-producers under anaerobic environment. Challenges and perspective of biohydrogen production with pure cultures are also outlined. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Maintaining yeast viability in continuous primary beer fermentation

    National Research Council Canada - National Science Library

    Pires, Eduardo J; Teixeira, José A; Brányik, Tomás; Côrte‐Real, Manuela; Vicente, António A

    2014-01-01

    .... This work was aimed at solving one of the most relevant obstacles to implementing ICT on a large scale in beer fermentations, namely the control of biomass and the maintenance of cell viability in a gas‐lift bioreactor...

  13. Continuous Cellulosic Bioethanol Fermentation by Cyclic Fed-Batch Cocultivation

    Science.gov (United States)

    Jiang, He-Long; He, Qiang; He, Zhili; Hemme, Christopher L.; Wu, Liyou

    2013-01-01

    Cocultivation of cellulolytic and saccharolytic microbial populations is a promising strategy to improve bioethanol production from the fermentation of recalcitrant cellulosic materials. Earlier studies have demonstrated the effectiveness of cocultivation in enhancing ethanolic fermentation of cellulose in batch fermentation. To further enhance process efficiency, a semicontinuous cyclic fed-batch fermentor configuration was evaluated for its potential in enhancing the efficiency of cellulose fermentation using cocultivation. Cocultures of cellulolytic Clostridium thermocellum LQRI and saccharolytic Thermoanaerobacter pseudethanolicus strain X514 were tested in the semicontinuous fermentor as a model system. Initial cellulose concentration and pH were identified as the key process parameters controlling cellulose fermentation performance in the fixed-volume cyclic fed-batch coculture system. At an initial cellulose concentration of 40 g liter−1, the concentration of ethanol produced with pH control was 4.5-fold higher than that without pH control. It was also found that efficient cellulosic bioethanol production by cocultivation was sustained in the semicontinuous configuration, with bioethanol production reaching 474 mM in 96 h with an initial cellulose concentration of 80 g liter−1 and pH controlled at 6.5 to 6.8. These results suggested the advantages of the cyclic fed-batch process for cellulosic bioethanol fermentation by the cocultures. PMID:23275517

  14. Operation of a two-stage continuous fermentation process producing hydrogen and methane from artificial food wastes

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, Kohki; Mizuno, Shiho; Umeda, Yoshito; Sakka, Makiko [Toho Gas Co., Ltd. (Japan); Osaka, Noriko [Tokyo Gas Co. Ltd. (Japan); Sakka, Kazuo [Mie Univ. (Japan)

    2010-07-01

    An anaerobic two-stage continuous fermentation process with combined thermophilic hydrogenogenic and methanogenic stages (two-stage fermentation process) was applied to artificial food wastes on a laboratory scale. In this report, organic loading rate (OLR) conditions for hydrogen fermentation were optimized before operating the two-stage fermentation process. The OLR was set at 11.2, 24.3, 35.2, 45.6, 56.1, and 67.3 g-COD{sub cr} L{sup -1} day{sup -1} with a temperature of 60 C, pH5.5 and 5.0% total solids. As a result, approximately 1.8-2.0 mol-H{sub 2} mol-hexose{sup -1} was obtained at the OLR of 11.2-56.1 g-COD{sub cr} L{sup -1} day{sup -1}. In contrast, it was inferred that the hydrogen yield at the OLR of 67.3 g-COD{sub cr} L{sup -1} day{sup -1} decreased because of an increase in lactate concentration in the culture medium. The performance of the two-stage fermentation process was also evaluated over three months. The hydraulic retention time (HRT) of methane fermentation was able to be shortened 5.0 days (under OLR 12.4 g-COD{sub cr} L{sup -1} day{sup -1} conditions) when the OLR of hydrogen fermentation was 44.0 g-COD{sub cr} L{sup -1} day{sup -1}, and the average gasification efficiency of the two-stage fermentation process was 81% at the time. (orig.)

  15. Modeling mixed culture fermentations; the role of different electron carriers.

    Science.gov (United States)

    Kleerebezem, R; Rodríguez, J; Temudo, M F; van Loosdrecht, M C M

    2008-01-01

    A recently established mixed culture fermentation (MCF) model has been modified to account for the role of different electron carriers in the process. The MCF-model predicts the product spectrum as a function of the actual environmental conditions using a thermodynamic optimization criterion while satisfying a number of constraints. Other improvements made to the original model are the inclusion of formate as fermentation end-product, and gas-liquid mass transfer. The model is adequately capable of reproducing experimental results in terms of butyrate and formate versus hydrogen/carbon dioxide production. The model is not capable of predicting the production of an ethanol/acetate mixture as measured at higher pH-values, suggesting specific biochemical control. Catabolic acetate production can potentially be explained by anabolic requirements for a specific electron donor like NADH.

  16. Feeding Aspergillus oryzae Fermentation Culture (AOFC) to Growing Sheep: 1. The Effect of AOFC on Rumen Fermentation

    OpenAIRE

    Darwinsyah Lubis; Elizabeth Wina; Budi Haryanto; T Suhargiyantatmo

    2002-01-01

    Cultures of fungi, especially Aspergillus oryzae, have been of interest to animal nutritionists to increase feed efficiency. Many experiments have been done and showed positive results on rumen fermentation and productivity of ruminants. This paper reports the results of an in vivo study on feeding Aspergillus oryzae, fermentation culture (AOFC) to growing sheep. ‘Onggok’ (tapioca processing waste) was used as media for AO cultivation after being enriched with a mineral mixture. Commercial co...

  17. Consistent 1,3-propanediol production from glycerol in mixed culture fermentation over a wide range of pH

    National Research Council Canada - National Science Library

    Moscoviz, Roman; Trably, Eric; Bernet, Nicolas

    2016-01-01

    ...) in fermentation processes. The aim of this study was to investigate the effect of initial pH on a batch mixed culture fermentation of glycerol, considering both the bacterial community composition and the fermentation patterns...

  18. Optimization of cyclosporin A production by Beauveria nivea in continuous fed-batch fermentation

    Directory of Open Access Journals (Sweden)

    Dong Huijun

    2011-01-01

    Full Text Available To develop the effective control method for fed-batch culture of cyclosporin A production, we chose fructose, L-valine and (NH42HPO4 as feeding nutrients and compared their productivities in relation to different concentrations. The feeding rate of three kinds of feeding materials was controlled to maintain the suitable residual concentration. The fed-batch fermentation results indicated that the optimal concentrations of fructose, L-valine and (NH42HPO4 were about 20 g/L, 0.5 g/L and 0.6 g/L for cyclosporin A production, respectively. The cultivation of Beauveria nivea could produce cyclosporin A up to 6.2 g/L for 240 hrs through a continuous feeding-rate-controlled-batch process under the optimal feeding conditions.

  19. Microbiological Study of Lactic Acid Fermentation of Caper Berries by Molecular and Culture-Dependent Methods

    OpenAIRE

    Pérez Pulido, Rubén; Ben Omar, Nabil; Abriouel, Hikmate; Lucas López, Rosario; Martínez Cañamero, Magdalena; Gálvez, Antonio

    2005-01-01

    Fermentation of capers (the fruits of Capparis sp.) was studied by molecular and culture-independent methods. A lactic acid fermentation occurred following immersion of caper berries in water, resulting in fast acidification and development of the organoleptic properties typical of this fermented food. A collection of 133 isolates obtained at different times of fermentation was reduced to 75 after randomly amplified polymorphic DNA (RAPD)-PCR analysis. Isolates were identified by PCR or 16S r...

  20. Modeling and Parameter Identification Involving 3-Hydroxypropionaldehyde Inhibitory Effects in Glycerol Continuous Fermentation

    Directory of Open Access Journals (Sweden)

    Zhaohua Gong

    2012-01-01

    Full Text Available Mathematical modeling and parameter estimation are critical steps in the optimization of biotechnological processes. In the 1,3-propanediol (1,3-PD production by glycerol fermentation process under anaerobic conditions, 3-hydroxypropionaldehyde (3-HPA accumulation would arouse an irreversible cessation of the fermentation process. Considering 3-HPA inhibitions to cells growth and to activities of enzymes, we propose a novel mathematical model to describe glycerol continuous cultures. Some properties of the above model are discussed. On the basis of the concentrations of extracellular substances, a parameter identification model is established to determine the kinetic parameters in the presented system. Through the penalty function technique combined with an extension of the state space method, an improved genetic algorithm is then constructed to solve the parameter identification model. An illustrative numerical example shows the appropriateness of the proposed model and the validity of optimization algorithm. Since it is difficult to measure the concentrations of intracellular substances, a quantitative robustness analysis method is given to infer whether the model is plausible for the intracellular substances. Numerical results show that the proposed model is of good robustness.

  1. Omega-3 production by fermentation of Yarrowia lipolytica: From fed-batch to continuous.

    Science.gov (United States)

    Xie, Dongming; Miller, Edward; Sharpe, Pamela; Jackson, Ethel; Zhu, Quinn

    2017-04-01

    The omega-3 fatty acid, cis-5,8,11,14,17-eicosapentaenoic acid (C20:5; EPA) has wide-ranging benefits in improving heart health, immune function, and mental health. A sustainable source of EPA production through fermentation of metabolically engineered Yarrowia lipolytica has been developed. In this paper, key fed-batch fermentation conditions were identified to achieve 25% EPA in the yeast biomass, which is so far the highest EPA titer reported in the literature. Dynamic models of the EPA fermentation process were established for analyzing, optimizing, and scaling up the fermentation process. In addition, model simulations were used to develop a two-stage continuous process and compare to single-stage continuous and fed- batch processes. The two stage continuous process, which is equipped with a smaller growth fermentor (Stage 1) and a larger production fermentor (Stage 2), was found to be a superior process to achieve high titer, rate, and yield of EPA. A two-stage continuous fermentation experiment with Y. lipolytica strain Z7334 was designed using the model simulation and then tested in a 2 L and 5 L fermentation system for 1,008 h. Compared with the standard 2 L fed-batch process, the two-stage continuous fermentation process improved the overall EPA productivity by 80% and EPA concentration in the fermenter by 40% while achieving comparable EPA titer in biomass and similar conversion yield from glucose. During the long-term experiment it was also found that the Y. lipolytica strain evolved to reduce byproduct and increase lipid production. This is one of the few continuous fermentation examples that demonstrated improved productivity and concentration of a final product with similar conversion yield compared with a fed-batch process. This paper suggests the two-stage continuous fermentation could be an effective process to achieve improved production of omega-3 and other fermentation products where non-growth or partially growth associated kinetics

  2. Breeding Strategy To Generate Robust Yeast Starter Cultures for Cocoa Pulp Fermentations.

    Science.gov (United States)

    Meersman, Esther; Steensels, Jan; Paulus, Tinneke; Struyf, Nore; Saels, Veerle; Mathawan, Melissa; Koffi, Jean; Vrancken, Gino; Verstrepen, Kevin J

    2015-09-01

    Cocoa pulp fermentation is a spontaneous process during which the natural microbiota present at cocoa farms is allowed to ferment the pulp surrounding cocoa beans. Because such spontaneous fermentations are inconsistent and contribute to product variability, there is growing interest in a microbial starter culture that could be used to inoculate cocoa pulp fermentations. Previous studies have revealed that many different fungi are recovered from different batches of spontaneous cocoa pulp fermentations, whereas the variation in the prokaryotic microbiome is much more limited. In this study, therefore, we aimed to develop a suitable yeast starter culture that is able to outcompete wild contaminants and consistently produce high-quality chocolate. Starting from specifically selected Saccharomyces cerevisiae strains, we developed robust hybrids with characteristics that allow them to efficiently ferment cocoa pulp, including improved temperature tolerance and fermentation capacity. We conducted several laboratory and field trials to show that these new hybrids often outperform their parental strains and are able to dominate spontaneous pilot scale fermentations, which results in much more consistent microbial profiles. Moreover, analysis of the resulting chocolate showed that some of the cocoa batches that were fermented with specific starter cultures yielded superior chocolate. Taken together, these results describe the development of robust yeast starter cultures for cocoa pulp fermentations that can contribute to improving the consistency and quality of commercial chocolate production. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  3. Continuous Fermentation of Clostridium tyrobutyricum with Partial Cell Recycle as a Long-Term Strategy for Butyric Acid Production

    Directory of Open Access Journals (Sweden)

    Edgar C. Clausen

    2012-08-01

    Full Text Available In making alternative fuels from biomass feedstocks, the production of butyric acid is a key intermediate in the two-step production of butanol. The fermentation of glucose via Clostridium tyrobutyricum to butyric acid produces undesirable byproducts, including lactic acid and acetic acid, which significantly affect the butyric acid yield and productivity. This paper focuses on the production of butyric acid using Clostridium tyrobutyricum in a partial cell recycle mode to improve fermenter yield and productivity. Experiments with fermentation in batch, continuous culture and continuous culture with partial cell recycle by ultrafiltration were conducted. The results show that a continuous fermentation can be sustained for more than 120 days, which is the first reported long-term production of butyric acid in a continuous operation. Further, the results also show that partial cell recycle via membrane ultrafiltration has a great influence on the selectivity and productivity of butyric acid, with an increase in selectivity from ≈9% to 95% butyric acid with productivities as high as 1.13 g/Lh. Continuous fermentation with low dilution rate and high cell recycle ratio has been found to be desirable for optimum productivity and selectivity toward butyric acid and a comprehensive model explaining this phenomenon is given.

  4. Influence of starter culture on flavor and headspace volatile profiles of fermented whey and whey produced from fermented milk.

    Science.gov (United States)

    Gallardo-Escamilla, F J; Kelly, A L; Delahunty, C M

    2005-11-01

    Rennet whey and skim milk were compared as media for fermentation by commercial cheese, yogurt, and probiotic starter cultures. Effect of culture, medium, and their interaction on flavor was assessed and compared by sensory descriptive analysis and headspace volatile analysis by proton transfer reaction-mass spectrometry. In general, the aroma of fermented whey was similar to that of whey separated from fermented milk, indicating a favorable possibility of substituting milk with whey in the manufacture of fermented milk-like beverages. Starter culture significantly affected most sensory characteristics of the products. Key volatile compounds for the characteristic flavor of yogurt, such as acetaldehyde and diacetyl, were not significantly affected by medium when fermented with the yogurt culture, and reached similar levels in both systems. Volatile analysis results were consistent with the results of the sensory evaluation, indicating the high reliability of proton transfer reaction-mass spectrometry in detecting important volatile compounds for aroma. Integration of this sensory and chemical information allows a better understanding of how flavor and related compounds are affected by ingredients or processing, which may be useful for the development of value-added whey products.

  5. Performance comparison of ethanol and butanol production in a continuous and closed-circulating fermentation system with membrane bioreactor.

    Science.gov (United States)

    Chen, Chunyan; Long, Sihua; Li, Airong; Xiao, Guoqing; Wang, Linyuan; Xiao, Zeyi

    2017-03-16

    Since both ethanol and butanol fermentations are urgently developed processes with the biofuel-demand increasing, performance comparison of aerobic ethanol fermentation and anerobic butanol fermentation in a continuous and closed-circulating fermentation (CCCF) system was necessary to achieve their fermentation characteristics and further optimize the fermentation process. Fermentation and pervaporation parameters including the average cell concentration, glucose consumption rate, cumulated production concentration, product flux, and separation factor of ethanol fermentation were 11.45 g/L, 3.70 g/L/h, 655.83 g/L, 378.5 g/m 2 /h, and 4.83, respectively, the corresponding parameters of butanol fermentation were 2.19 g/L, 0.61 g/L/h, 28.03 g/L, 58.56 g/m 2 /h, and 10.62, respectively. Profiles of fermentation and pervaporation parameters indicated that the intensity and efficiency of ethanol fermentation was higher than butanol fermentation, but the stability of butanol fermentation was superior to ethanol fermentation. Although the two fermentation processes had different features, the performance indicated the application prospect of both ethanol and butanol production by the CCCF system.

  6. Selection of microalgae suitable for culturing with digestate from methane fermentation.

    Science.gov (United States)

    Khanh, N; Kitaya, Y; Xiao, L; Endo, R; Shibuya, T

    2013-01-01

    The effects ofdigestate on the growth rates of Euglena gracilis, Chlorella vulgaris, and Dunaliella tertiolecta were investigated to select suitable microalgae for culturing with digestate from methane fermentation. Microalgae were cultured in an aqueous solution containing digestate at concentrations of 5%, 10%, 13%, 20%, 40%, 50%, and 100%, and Cramer-Myers (CM) solution as a control, at photosynthetic photon flux densities (PPFDs) of 75-150 micromol m(-2) s(-1) with continuous illumination at 30 degrees C. The number of cells was monitored daily, and specific growth rates (mu) were calculated as cellular multiplication rates. The maximum mu values of these species were greater in appropriate concentrations of digestate than in CM medium. The maximum mu values were 0.047 h(-1) in 10% digestate for E. gracilis, 0.065 h(-1) in 20% digestate for C. vulgaris, and 0.052 h(-1) in 50% digestate for D. tertiolecta at a PPFD of 150 micromol m(-2) s(-1). The mu of D. tertiolecta were 2.5 and 1.1 times higher than those of E. gracilis and C. vulgaris, respectively, in 50% digestate. These results demonstrated that these species could be cultured at high growth rates with diluted methane fermentation sludge and that, among these species, Dunaliella sp. was suitable for culturing at higher concentration of digestate under relatively low-level light conditions.

  7. Acid protease and formation of multiple forms of glucoamylase in batch and continuous cultures of Aspergillus niger

    DEFF Research Database (Denmark)

    Aalbæk, Thomas; Reeslev, Morten; Jensen, Bo

    2002-01-01

    In order to identify factors responsible for production of multiple forms of glucoamylase (GA) by Aspergillus niger Bo-1, the fungus was cultured in both complex and defined media in pH-controlled batch fermenters and chemostats. At all culture conditions three forms of GA were produced...... was cultivated in batch and continuous fermentations with a constant pH of 3.0 or 5.0, whereas acidification of both complex and defined batch culture media after 20 h of growth induced a significant secretion of acid protease(s). The protease(s) present in the complex medium catalysed modification...... with molecular weights of approx. 91 (GAI), 73 (GAII), and 59 kDa (GAIII). Data from batch fermentations with constant pH 3.0 and 5.0 showed a uniform distribution of extracellular GA forms throughout the fermentations and independent of culture growth phases. Furthermore, steady-state data from chemostat...

  8. Acid protease and formation of multiple forms of glycoamylase in batch and continuous cultures of Aspergillus niger

    DEFF Research Database (Denmark)

    Aalbæk, Thomas; Reeslev, Morten; Jensen, Bo

    2002-01-01

    In order to identify factors responsible for production of multiple forms of glucoamylase (GA) by Aspergillus niger Bo-1, the fungus was cultured in both complex and defined media in pH-controlled batch fermenters and chemostats. At all culture conditions three forms of GA were produced...... was cultivated in batch and continuous fermentations with a constant pH of 3.0 or 5.0, whereas acidification of both complex and defined batch culture media after 20 h of growth induced a significant secretion of acid protease(s). The protease(s) present in the complex medium catalysed modification...... with molecular weights of approx. 91 (GAI), 73 (GAII), and 59 kDa (GAIII). Data from batch fermentations with constant pH 3.0 and 5.0 showed a uniform distribution of extracellular GA forms throughout the fermentations and independent of culture growth phases. Furthermore, steady-state data from chemostat...

  9. Temperature control in a continuously mixed bioreactor for solid-state fermentation

    NARCIS (Netherlands)

    Nagel, F.J.J.I.; Tramper, J.; Bakker, M.S.N.; Rinzema, A.

    2001-01-01

    A continuously mixed, aseptic paddle mixer was used successfully for solid-state fermentation (SSF) with Aspergillus oryzae on whole wheat kernels. Continuous mixing improved temperature control and prevented inhomogeneities in the bed. Respiration rates found in this system were comparable to those

  10. Microbe-microbe interactions in mixed culture food fermentations

    NARCIS (Netherlands)

    Smid, E.J.; Lacroix, C.

    2013-01-01

    Most known natural and industrial food fermentation processes are driven by either simple or complex communities of microorganisms. Obviously, these fermenting microbes will not only interact with the fermentable substrate but also with each other. These microbe–microbe interactions are complex but

  11. A membrane-integrated fermentation reactor system: its effects in reducing the amount of sub-raw materials for D-lactic acid continuous fermentation by Sporolactobacillus laevolacticus.

    Science.gov (United States)

    Mimitsuka, Takashi; Na, Kyungsu; Morita, Ken; Sawai, Hideki; Minegishi, Shinichi; Henmi, Masahiro; Yamada, Katsushige; Shimizu, Sakayu; Yonehara, Tetsu

    2012-01-01

    Continuous fermentation by retaining cells with a membrane-integrated fermentation reactor (MFR) system was found to reduce the amount of supplied sub-raw material. If the amount of sub-raw material can be reduced, continuous fermentation with the MFR system should become a more attractive process for industrialization, due to decreased material costs and loads during the refinement process. Our findings indicate that the production rate decreased when the amount of the sub-raw material was reduced in batch fermentation, but did not decrease during continuous fermentation with Sporolactobacillus laevolacticus. Moreover, continuous fermentation with a reduced amount of sub-raw material resulted in a productivity of 11.2 g/L/h over 800 h. In addition, the index of industrial process applicability used in the MFR system increased by 6.3-fold as compared with the conventional membrane-based fermentation reactor previously reported, suggesting a potential for the industrialization of this D-lactic acid continuous fermentation process.

  12. On-Line Optimizing Control of a Simulated Continuous Yeast Fermentation

    DEFF Research Database (Denmark)

    Andersen, Maria Y.; Asferg, L.; Brabrand, H.

    1989-01-01

    On-line optimizing control of a simulated fermentation is investigated using a non-segregated dynamic model of aerobic glucose limited growth of saccharomyces cerevisiae. The optimization procedure is carried out with an underlying adaptive regulator to stabilize the culture. This stabilization i...

  13. Clostridium strain co-cultures for biohydrogen production enhancement from condensed molasses fermentation solubles

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, Chin-Lang; Wu, Jou-Hsien; Lin, Chiu-Yue [BioHydrogen Lab, Graduate Institute of Civil and Hydraulic Engineering, Feng Chia University, Taichung (China); Chang, Jui-Jen [Genomics Research Center, Academia Sinica, Taipei (China); Department of Life Sciences, National Chung Hsing University, Taichung (China); Chin, Wei-Chih; Wen, Fu-Shyan; Huang, Chieh-Chen [Department of Life Sciences, National Chung Hsing University, Taichung (China); Chen, Chin-Chao [Environmental Resources Laboratory, Department of Landscape Architecture, Chungchou Institute of Technology, Changhwa (China)

    2009-09-15

    An anaerobic continuous-flow hydrogen fermentor was operated at a hydraulic retention time of 8 h using condensed molasses fermentation solubles (CMS) substrate of 40 g-COD/L. Serum bottles were used for seed micro-flora cultivation and batch hydrogen fermentation tests (CMS substrate concentrations of 10-160 g-COD/L). Three hydrogen-producing bacterial strains Clostridium sporosphaeroides F52, Clostridium tyrobutyricum F4 and Clostridium pasteurianum F40 were isolated from the seed fermentor and used as the seeding microbes in single and mixed-culture cultivations for determining their hydrogen productivity. These strains possessed specific hydrogenase genes that could be detected from CMS-fed hydrogen fermentors and were major hydrogen producers. C. pasteurianum F40 was the dominant strain with a high hydrogen production rate while C. sporosphaeroides F52 may play a main role in degrading carbohydrate and glutamate. These strains could be co-cultivated as a symbiotic mixed-culture process to enhance hydrogen productivity. C. pasteurianum F40 or C. tyrobutyricum F4 co-culture with the glutamate-utilizing strain C. sporosphaeroides F52 efficiently enhanced hydrogen production by 12-220% depending on the substrate CMS concentrations. (author)

  14. Production of teicoplanin by Actinoplanes teichomyceticus in continuous fermentation

    DEFF Research Database (Denmark)

    Vara, A.G.; Hochkoepple, A.; Nielsen, Jens

    2002-01-01

    Production of the potent antibiotic teicoplanin by Actinoplanes teichomyceticus was studied in batch and in chemostat cultures. It is found that the producing strain deactivates to a non-producing strain named NP-12. This strain is used to find the growth kinetics of the A. teichomyceticus withou...

  15. Semi-Continuous Fermentation of Onion Vinegar and Its Functional Properties.

    Science.gov (United States)

    Lee, Sulhee; Lee, Jin-A; Park, Gwi-Gun; Jang, Jae-Kweon; Park, Young-Seo

    2017-08-08

    For the fermentation of vinegar using onion, acetic acid bacteria and yeast strains with high fermentation ability were screened. Among them, Saccharomyces cerevisiae 1026 was selected as a starter for ethanol production and Acetobacter orientalis MAK88 was selected as a vinegar producer. When the two-stage fermentation of onion vinegar was performed at 28 °C, the titratable acidity reached 4.80% at 24 h of fermentation. When semi-continuous fermentation proceeded to charge-discharge consisting of three cycles, the acetic acid content reached 4.35% at 48 h of fermentation. At this stage, the fermentation efficiency, acetic acid productivity, and specific product formation rate were 76.71%, 17.73 g/(L·d), and 20.58 g/(g·h), respectively. The process in this study significantly reduced the fermentation time and simplified the vinegar production process. The content of total flavonoids and total polyphenols in onion vinegar were 104.36 and 455.41 μg/mL, respectively. The antioxidant activities of onion vinegar in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic) acid (ABTS⁺) radical scavenging activity, and reducing power were 75.33%, 98.88%, and 1.28, respectively. The nitrite scavenging abilities of onion vinegar were 95.38 at pH 1.2. The onion vinegar produced in this study showed higher organoleptic acceptability than commercial onion vinegar.

  16. Dynamics of Cocoa Bean Pulp Degradation during Cocoa Bean Fermentation: Effects of Yeast Starter Culture Addition

    Directory of Open Access Journals (Sweden)

    Laras Cempaka

    2014-07-01

    Full Text Available Fermentation is a crucial step in the post-harvest processing of cocoa beans. This process comprises mixed culture microbial activities on the cocoa bean pulp, producing metabolites that act as important precursors for cocoa flavour development. Variations in the microbial population dynamics during the fermentation process may induce changes in the overall process. Thus, the introduction of a specific microbial starter culture may improve the quality of the fermentation. This article discusses the effects ofthe addition of Saccharomyces cerevisae var. Chevalieri starter culture on cocoa bean fermentation. The dynamics in the yeast concentration, sugary pulp compounds and metabolic products were measured during fermentation. The alterations in the dynamic metabolite profile were significant, although only a slight difference was observed in the yeast population. A higher fermentation index was measured for the cocoa bean fermentation with yeast starter culture, 1.13 compared to 0.84. In conclusion, this method can potentially be applied to shorten the cocoa bean fermentation time.

  17. The use of starter cultures in the fermentation of bushera: a ...

    African Journals Online (AJOL)

    Mo

    under poor hygienic conditions and there is therefore a need to improve the safety and quality of bushera. Sanni (1993) and Kimaryo et al. (2000) indicated that the use of starter cultures containing microorganisms isolated from fermented cereal foods for fermentation could suffice to control the process and thereby alleviate ...

  18. Linking microbial community structure and product spectrum of rice straw fermentation with undefined mixed culture

    Science.gov (United States)

    Ai, Binling; Chi, Xue; Meng, Jia; Sheng, Zhanwu; Zheng, Lili; Zheng, Xiaoyan; Li, Jianzheng

    2017-12-01

    Undefined mixed culture-based fermentation is an alternative strategy for biofuels and bioproducts production from lignocellulosic biomass without supplementary cellulolytic enzymes. Mixed culture produces mixed carboxylates. To estimate the relationship between microbial community structure and product spectrum, carboxylate production was initiated by mixed cultures with different microbial community structure. All the inoculum cultures were derived from the same enrichment culture from the combination of cattle manure, pig manure compost, corn field soil and rotten wood. Due to the differences in the preparation method and culture time, the inoculum cultures for batch fermentation had high similarity in microbial community structure, while the community structure of each inoculum culture for repeated batch fermentation differed from that of another. The inoculum cultures with similar community structure led to a similar product spectrum. In batch fermentation, the selectivity of main product butyric acid stabilized around 76%. The inoculum cultures with different community structures resulted in different product spectra. In repeated batch fermentation, the butyric acid content gradually decreased to 27%, and the by-product acetic acid content steadily increased to 56%. The other by-products including propionic, valeric and caproic acids were also increased. It is deduced that keeping the microbial community structure stable makes the basic and key precondition for steady production of specific carboxylic acid with undefined mixed culture.

  19. Fermentation of six different forages in the semi-continuous fermentation technique Caesitec.

    Science.gov (United States)

    Vosmer, J; Liesegang, A; Wanner, M; Zeyner, A; Suter, D; Hoelzle, L; Wichert, B

    2012-10-01

    The aim of the present study was to compare carbohydrate degradation of forages which store carbohydrates either predominantly as fructan or starch, in horses' hindgut. The effects of an abrupt change from hay-based feeding to green fodder-based feeding on the caecal flora were tested with the in vitro hindgut simulation technique 'Caesitec'. Six trials with different forages (English ryegrass, tall fescue, grass mixture-horses, grass mixture-cows, lucerne, white clover) were conducted. During a 4-day stabilisation period, samples were taken once a day before loading the fermenters with hay. After diet-change to forage-based feeding, samples were taken four times a day. Ammonia and pH-value were measured before and 1, 2 and 6 h after loading the 'Caesitec'. Gas formation was measured daily. Bacterial numbers, lactate and short chain fatty acids were detected at four time-points of each trial. The grass mixtures contained the highest amounts of fructan. The pH-values were in the physiological range from pH 6 up to 7 (6.58-6.83) by feeding all forages. Gas formation, anaerobic and aerobic bacterial numbers increased after diet change from hay to any forage. The maximum amount of fructan (3.75 g/kg) in swiss pasture did not cause a permanent pathological change in the hindgut-flora. © 2012 Blackwell Verlag GmbH.

  20. Ziziphus mauritiana (masau) fruits fermentation in Zimbabwe: from black-box to starter culture development

    NARCIS (Netherlands)

    Nyanga, L.K.

    2012-01-01

    This thesis reports on studies of microbiological and biochemical properties of masau (Ziziphus mauritiana) fruit fermentation and the development of starter cultures for the production of masau beverages. A survey to document the traditional processing techniques was conducted using a

  1. Potential of LAB starter culture isolated from Chinese traditional fermented foods for yoghurt production

    National Research Council Canada - National Science Library

    Han, Xue; Zhang, Lanwei; Yu, Peng; Yi, Huaxi; Zhang, YingChun

    2014-01-01

    ... 4.5 was the best combination and better than the commercial starter culture in terms of yoghurt fermentation time and sensory quality, suggesting that the combination has potential as a commercial starter to improve the quality of yoghurt.

  2. Optimum alcohol concentration for chain elongation in mixed-culture fermentation of cellulosic substrate.

    Science.gov (United States)

    Lonkar, Sagar; Fu, Zhihong; Holtzapple, Mark

    2016-12-01

    Medium-chain fatty acids (MCFA, e.g., caproic, heptanoic, caprylic acid) are more valuable than short-chain fatty acids (SCFA, e.g., acetic, propionic, butyric, valeric acid). SCFAs are major products in methane-inhibited mixed-culture anaerobic fermentation. By feeding ethanol to the fermentor, MCFA formation is enhanced through chain elongation. Microorganisms such as Clostridium kluyveri elongate short-chain acids by combining them with alcohol. Very low ethanol concentration reduces chain elongation rates, whereas very high ethanol concentrations inhibit microorganisms. To maximize MCFA production, different ethanol concentrations were investigated in the mixed-culture fermentation of office paper and chicken manure. At 10 g/L ethanol concentration, 10 g/L MCFA was formed. High ethanol concentrations (above 40 g/L) inhibit microorganisms resulting in no chain elongation. For chain elongation, propanol was found to be more inhibitory than ethanol. The data suggest that MCFA production will increase by continuously extracting MCFA and maintaining 5-10 g/L ethanol concentration by periodic addition. Biotechnol. Bioeng. 2016;113: 2597-2604. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  3. Impact of operating history on mixed culture fermentation microbial ecology and product mixture.

    Science.gov (United States)

    Lu, Y; Slater, F R; Mohd-Zaki, Z; Pratt, S; Batstone, D J

    2011-01-01

    Mixed culture fermentation is an alternative to pure culture fermentation for production of biofuels and valuable products. A glucose-fed, continuous reactor was operated cyclically to a central pH of 5.5 from a number of precedent pHs, from 4.5 to 7.5. At each pH, stable chemical production was reached after 2 retention times and was held for least 2 further retention times prior to the next change. Bacterial groups were identified by phylogenetic analysis of 16S rRNA gene clones. Bacterial community dynamics were monitored by terminal-restriction fragment length polymorphism. More ethanol was produced at high pH, and more butyrate at lower pH. At pH 5.5, the product spectrum was not measurably influenced by precedent pH but showed seemingly random changes. The impact of precedent pH on community structure was more systematic, with clear indications that when the pH was returned to 5.5, the bacterial group that was dominant at the precedent pH remained at high abundance. This result is important, since it indicates a decoupling between microbial function (as indicated by product spectrum), and community structure. More work is needed to determine the longevity of this hysteresis effect. There was evidence that groups retained their ability to re-emerge even after times of low abundance.

  4. On-line monitoring of important organoleptic methyl-branched aldehydes during batch fermentation of starter culture Staphylococcus xylosus reveal new insight into their production in a model fermentation

    DEFF Research Database (Denmark)

    de Vos Petersen, Christian; Beck, Hans Christian; Lauritsen, Frants R

    2004-01-01

    A small fermentor (55 mL) was directly interfaced to a membrane inlet mass spectrometer for continuous on-line monitoring of oxygen and volatile metabolites during batch fermentations of the starter culture Staphylococcus xylosus. Using this technique, we were able to correlate production...

  5. Continuous determination of volatile products in anaerobic fermenters by on-line capillary gas chromatography.

    Science.gov (United States)

    Diamantis, V; Melidis, P; Aivasidis, A

    2006-07-28

    Bio-ethanol and biogas produced during the anaerobic conversion of organic compounds has been a subject of great interest since the oil crisis of the 1970s. In ethanol fermentation and anaerobic treatment of wastewaters, end-product (ethanol) and intermediate-products (short-chain fatty acids, SCFA) cause inhibition that results in reduced process efficiency. Control of these constituents is of utmost importance for bioreactor optimization and process stability. Ethanol and SCFA can be detected with precision by capillary gas chromatography usually conducted in off-line measurements. In this work, an on-line monitoring and controlling system was developed and connected to the fermenter via an auto-sampling equipment, which could perform the feeding, filtration and dilution of the sample and final injection into the gas chromatograph through an automation-based programmed procedure. The sample was continuously pumped from the recycle stream of the bioreactor and treated using a microfiltration unit. The concentrate was returned to the reactor while the permeate was quantitatively mixed with an internal standard solution. The system comprised of a gas chromatograph with the flow cell and one-shot sampler and a PC with the appropriate software. The on-line measurement of ethanol and SCFA, directly from the liquid phase of an ethanol fermenter and a high-rate continuous mode anaerobic digester, was accomplished by gas chromatography. Also, this monitoring and controlling system was proved to be effective in the continuous fermentation of alcohol-free beer.

  6. Methane production from Parthenium hysterophorus L. , a terrestrial weed, in semi-continuous fermenters

    Energy Technology Data Exchange (ETDEWEB)

    Gunaseelan, V.N. (PSG Coll. of Arts and Science, Coimbatore (India). Dept. of Zoology)

    1994-01-01

    Anaerobic fermentation of untreated and NaOH-treated Parthenium for CH[sub 4] production was investigated in 31 semi-continuous fermenters. The experiments included investigation of the effect of retention time, loading rate, feeding frequency and temperature on the steady-state methane production. Results showed volumetric methane productivity of 456 ml CH[sub 4]1[sup -1]day[sup -1] for untreated Parthenium at 10 day retention time and 30[sup o]C. Alkali treatment with NaOH significantly enhanced the methane production and cellulose reduction. The results of this study are projected to the family-size Deenbandhu biogas fermenter which has become popular recently in India and the energy production is estimated. The methane yield for Parthenium is compared with the reported yields of methane for weeds. (Author)

  7. Improvement on the productivity of continuous tequila fermentation by Saccharomyces cerevisiae of Agave tequilana juice with supplementation of yeast extract and aeration.

    Science.gov (United States)

    Hernández-Cortés, Guillermo; Valle-Rodríguez, Juan Octavio; Herrera-López, Enrique J; Díaz-Montaño, Dulce María; González-García, Yolanda; Escalona-Buendía, Héctor B; Córdova, Jesús

    2016-12-01

    Agave (Agave tequilana Weber var. azul) fermentations are traditionally carried out employing batch systems in the process of tequila manufacturing; nevertheless, continuous cultures could be an attractive technological alternative to increase productivity and efficiency of sugar to ethanol conversion. However, agave juice (used as a culture medium) has nutritional deficiencies that limit the implementation of yeast continuous fermentations, resulting in high residual sugars and low fermentative rates. In this work, fermentations of agave juice using Saccharomyces cerevisiae were put into operation to prove the necessity of supplementing yeast extract, in order to alleviate nutritional deficiencies of agave juice. Furthermore, continuous fermentations were performed at two different aeration flow rates, and feeding sterilized and non-sterilized media. The obtained fermented musts were subsequently distilled to obtain tequila and the preference level was compared against two commercial tequilas, according to a sensorial analysis. The supplementation of agave juice with air and yeast extract augmented the fermentative capacity of S. cerevisiae S1 and the ethanol productivities, compared to those continuous fermentations non supplemented. In fact, aeration improved ethanol production from 37 to 40 g L(-1), reducing sugars consumption from 73 to 88 g L(-1) and ethanol productivity from 3.0 to 3.2 g (Lh)(-1), for non-aerated and aerated (at 0.02 vvm) cultures, respectively. Supplementation of yeast extract allowed an increase in specific growth rate and dilution rates (0.12 h(-1), compared to 0.08 h(-1) of non-supplemented cultures), ethanol production (47 g L(-1)), reducing sugars consumption (93 g L(-1)) and ethanol productivity [5.6 g (Lh)(-1)] were reached. Additionally, the effect of feeding sterilized or non-sterilized medium to the continuous cultures was compared, finding no significant differences between both types of cultures. The overall effect

  8. Genomic expression program of Saccharomyces cerevisiae along a mixed-culture wine fermentation with Hanseniaspora guilliermondii.

    Science.gov (United States)

    Barbosa, Catarina; Mendes-Faia, Arlete; Lage, Patrícia; Mira, Nuno P; Mendes-Ferreira, Ana

    2015-08-28

    The introduction of yeast starter cultures consisting in a blend of Saccharomyces cerevisiae and non-Saccharomyces yeast strains is emerging for production of wines with improved complexity of flavor. The rational use of this approach is, however, dependent on knowing the impact that co-inoculation has in the physiology of S. cerevisiae. In this work the transcriptome of S. cerevisiae was monitored throughout a wine fermentation, carried out in single culture or in a consortium with Hanseniaspora guilliermondii, this being the first time that this relevant yeast-yeast interaction is examined at a genomic scale. Co-inoculation with H. guilliermondii reduced the overall genome-wide transcriptional response of S. cerevisiae throughout the fermentation, which was attributable to a lower fermentative activity of S. cerevisiae while in the mixed-fermentation. Approximately 350 genes S. cerevisiae genes were found to be differently expressed (FDR fermentation medium. Genes involved in biosynthesis of vitamins were enriched among those up-regulated in the mixed-culture fermentation, while genes related with the uptake and biosynthesis of amino acids were enriched among those more expressed in the single-culture. The differences in the aromatic profiles of wines obtained in the single and in the mixed-fermentations correlated with the differential expression of S. cerevisiae genes encoding enzymes required for formation of aroma compounds. By integrating results obtained in the transcriptomic analysis performed with physiological data our study provided, for the first time, an integrated view into the adaptive responses of S. cerevisiae to the challenging environment of mixed culture fermentation. The availability of nutrients, in particular, of nitrogen and vitamins, stands out as a factor that may determine population dynamics, fermentative activity and by-product formation.

  9. Continuous two stage acetone-butanol-ethanol fermentation with integrated solvent removal using Clostridium acetobutylicum B 5313.

    Science.gov (United States)

    Bankar, Sandip B; Survase, Shrikant A; Singhal, Rekha S; Granström, Tom

    2012-02-01

    The objective of this study was to optimize continuous acetone-butanol-ethanol (ABE) fermentation using a two stage chemostat system integrated with liquid-liquid extraction of solvents produced in the first stage. This minimized end product inhibition by butanol and subsequently enhanced glucose utilization and solvent production in continuous cultures of Clostridium acetobutylicum B 5313. During continuous two-stage ABE fermentation, sugarcane bagasse was used as the cell holding material for the both stages and liquid-liquid extraction was performed using an oleyl alcohol and decanol mixture. An overall solvent production of 25.32g/L (acetone 5.93g/L, butanol 16.90g/L and ethanol 2.48g/L) was observed as compared to 15.98g/L in the single stage chemostat with highest solvent productivity and solvent yield of 2.5g/Lh and of 0.35g/g, respectively. Maximum glucose utilization (83.21%) at a dilution rate of 0.051/h was observed as compared to 54.38% in the single stage chemostat. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Effect of temperature on continuous dry fermentation of swine manure.

    Science.gov (United States)

    Deng, Liangwei; Chen, Chuang; Zheng, Dan; Yang, Hongnan; Liu, Yi; Chen, Ziai

    2016-07-15

    Laboratory-scale experiments were performed on the dry digestion of solid swine manure in a semi-continuous mode using 4.5 L down plug-flow anaerobic reactors with an organic loading rate of 3.46 kg volatile solids (VS) m(-3) d(-1) to evaluate the effects of temperature (15, 25 and 35 °C). At 15 °C, biogas production was the poorest due to organic overload and acidification, with a methane yield of 0.036 L CH4 g(-1) VS added and a volumetric methane production rate of 0.125 L CH4 L(-1) d(-1). The methane yield and volumetric methane production rate at 25 °C (0.226 L CH4 g(-1) VS added and 0.783 L CH4 L(-1) d(-1), respectively) were 6.24 times higher than those at 15 °C. However, the methane yield (0.237 L CH4 g(-1) VS added) and the volumetric methane production rate (0.821 L CH4 L(-1) d(-1)) at 35 °C were only 4.86% higher than those at 25 °C, which indicated similar results were obtained at 25 °C and 35 °C. The lower biogas production at 35 °C in dry digestion compared with that in wet digestion could be attributed to ammonia inhibition. For a single pig farm, digestion of solid manure is accomplished in small-scale domestic or small-farm bioreactors, for which operating temperatures of 35 °C are sometimes difficult to achieve. Considering biogas production, ammonia inhibition and net energy recovery, an optimum temperature for dry digestion of solid swine manure is 25 °C. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Effects of sequential mixed cultures of Wickerhamomyces anomalus and Saccharomyces cerevisiae on apple cider fermentation.

    Science.gov (United States)

    Ye, Mengqi; Yue, Tianli; Yuan, Yahong

    2014-09-01

    The fermentation of cider by mixed cultures of Wickerhamomyces anomalus and Saccharomyces cerevisiae was carried out to study their effect on the cider quality. The results showed that growth of W. anomalus and S. cerevisiae was affected by each other during co-fermentation process. All the mixed cultures produced statistically the same level of ethanol as S. cerevisiae monoculture. The mixed fermentation could produce more variety and higher amounts of acetate esters, ethyl esters, higher alcohols, aldehydes, and ketones. Sensory evaluation demonstrated that ciders obtained from co-fermentation with W. anomalus gained higher scores than ciders fermented by pure S. cerevisiae, especially the co-fermentation cultures WS3, WS4, WS6, and WS8. Only 3 days of fermentation with W. anomalus in sequential mixtures were enough to improve the quality of cider. Wickerhamomyces anomalus could be used in association with S. cerevisiae to improve the quality of cider. The modulation of inoculation time may provide an effective means of manipulating cider aroma for different characteristics. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  12. Halobacterium sp. SP1(1) as a starter culture for accelerating fish sauce fermentation.

    Science.gov (United States)

    Akolkar, A V; Durai, D; Desai, A J

    2010-07-01

    Application of Halobacterium sp. SP1(1) for the acceleration of fish sauce fermentation. Traditional fish sauce fermentation was mimicked using Halobacterium sp. SP1(1) as starter culture. Protease activity, peptide release and α-amino content (parameters used to monitor the progress of the fermentation) were high at day 10 in tests and day 20 in un-inoculated controls. The total protein and nitrogen contents were also high in tests compared with controls. The amino acid profile observed at the end of fermentation in experimental samples, when compared with the commercial sauce preparation, was found to be better with respect to flavour and aroma contributing amino acids as well as essential amino acid lysine. Microflora analysis of the final fish sauce revealed the absence of any nonhalophilic or halotolerant micro-organisms. The protease-producing halophilic isolates obtained from the fish sauce of eviscerated and uneviscerated controls were identified as Halobacterium sp. F1 and F2, respectively, by 16S rDNA sequence analysis. Exogenous augmentation of Halobacterium sp. SP1(1) accelerated the fish sauce fermentation process with an additive effect on the existing natural microflora present in the fish during fermentation. Halobacterium sp SP1(1), therefore, can be used as an important starter culture for accelerating the fish fermentation process, which is attributed to its extracellular protease. The present study is the first report on use of Halobacterium species as a starter culture for accelerating fish sauce fermentation. Use of halobacterial starter cultures may revolutionize the process in fish sauce industries by reducing the fermentation time and making the process more economical with improved nutritive value of product. Journal compilation © 2009 The Society for Applied Microbiology. No claim to Indian Government works.

  13. Continuous xylose fermentation by Candida shehatae in a two-stage reactor

    Science.gov (United States)

    M. A. Alexander; T. W. Chapman; T. W. Jeffries

    1988-01-01

    Recent work has identified ethanol toxicity as a major factor preventing continuous production of ethanol at the concentrations obtainable in batch culture. In this paper we investigate the use of a continuous two-stage bioreactor design to circumvent toxic effects of ethanol. Biomass is produced via continuous culture in the first stage reactor in which ethanol...

  14. Optimization of fermentation parameters to study the behavior of selected lactic cultures on soy solid state fermentation.

    Science.gov (United States)

    Rodríguez de Olmos, A; Bru, E; Garro, M S

    2015-03-02

    The use of solid fermentation substrate (SSF) has been appreciated by the demand for natural and healthy products. Lactic acid bacteria and bifidobacteria play a leading role in the production of novel functional foods and their behavior is practically unknown in these systems. Soy is an excellent substrate for the production of functional foods for their low cost and nutritional value. The aim of this work was to optimize different parameters involved in solid state fermentation (SSF) using selected lactic cultures to improve soybean substrate as a possible strategy for the elaboration of new soy food with enhanced functional and nutritional properties. Soy flour and selected lactic cultures were used under different conditions to optimize the soy SSF. The measured responses were bacterial growth, free amino acids and β-glucosidase activity, which were analyzed by applying response surface methodology. Based on the proposed statistical model, different fermentation conditions were raised by varying the moisture content (50-80%) of the soy substrate and temperature of incubation (31-43°C). The effect of inoculum amount was also investigated. These studies demonstrated the ability of selected strains (Lactobacillus paracasei subsp. paracasei and Bifidobacterium longum) to grow with strain-dependent behavior on the SSF system. β-Glucosidase activity was evident in both strains and L. paracasei subsp. paracasei was able to increase the free amino acids at the end of fermentation under assayed conditions. The used statistical model has allowed the optimization of fermentation parameters on soy SSF by selected lactic strains. Besides, the possibility to work with lower initial bacterial amounts to obtain results with significant technological impact was demonstrated. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Model predictive control algorithms and their application to a continuous fermenter

    Directory of Open Access Journals (Sweden)

    R. G. SILVA

    1999-06-01

    Full Text Available In many continuous fermentation processes, the control objective is to maximize productivity per unit time. The optimum operational point in the steady state can be obtained by maximizing the productivity rate using feed substrate concentration as the independent variable with the equations of the static model as constraints. In the present study, three model-based control schemes have been developed and implemented for a continuous fermenter. The first method modifies the well-known dynamic matrix control (DMC algorithm by making it adaptive. The other two use nonlinear model predictive control algorithms (NMPC, nonlinear model predictive control for calculation of control actions. The NMPC1 algorithm, which uses orthogonal collocation in finite elements, acted similar to NMPC2, which uses equidistant collocation. These algorithms are compared with DMC. The results obtained show the good performance of nonlinear algorithms.

  16. Glucoamylases production of Aspergillus niger in solid state fermentation using a continuous counter-current reactor

    OpenAIRE

    Varzakas, T. H.; Roussos, Sevastianos; Arvanitoyannis, I. S.

    2008-01-01

    This work presents the continuous production of fungal biomass and glucoamylase by solid state fermentation (SSF) in a counter-current reactor adapted for this purpose. Pre-germinated conidia of Aspergillus niger were used as an inoculum, and sugarcane bagasse, embedded with a nutritive solution, was the solid support. The solids residence time distribution (RTD) was carried out by feeding one impule of blue-coloured humidified bagasse and its RTD was fixed at 20 h. This study demonstrated th...

  17. Effect of temperature and temperature shock on the stability of continuous cellulosic-hydrogen fermentation.

    Science.gov (United States)

    Gadow, Samir I; Jiang, Hongyu; Watanabe, Ryoya; Li, Yu-You

    2013-08-01

    Three continuous stirred tank reactors (CSTR) were operated under mesophilic (37 ± 1°C), thermophilic (55 ± 1°C) and hyper-thermophilic (80 ± 1°C) temperatures for 164 days to investigate the effect of temperature and temperature shock on the cellulosic-dark hydrogen fermentation by mixed microflora. During steady state condition, the sudden decreases in the fermentation temperature occurred twice in each condition for 24h. The results show that the 55 ± 1 and 80 ± 1°C presented stable hydrogen yields of 12.28 and 9.72 mmol/g cellulose, respectively. However, the 37 ± 1°C presented low hydrogen yield of 3.56 mmol/g cellulose and methane yield of 5.4 mmol/g cellulose. The reactor performance under 55 ± 1 or 80 ± 1°C appeared to be more resilient to the sudden decreases in the fermentation temperature than 37 ± 1°C. The experimental analysis results indicated that the changing in soluble by-products could explain the effect of temperature and temperature shock, and the thermophilic temperature is expected having a better economic performance for cellulosic-hydrogen fermentation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Process of preparing ethanol by continuous fermentation of polysaccharide-containing materials

    Energy Technology Data Exchange (ETDEWEB)

    Ehnstroem, L.K.J.

    1981-04-16

    The invention concerns a process of preparing ethanol by continuous fermentation of polysaccharide - containing raw materials. Fermentation, hereby, occurs in one or several fermentors while dividing one stream of the fermentation liquid into a yeast-concentrate stream and a yeast-free stream and, if neccessary, a sludge stream. The yeast-concentrate stream is re-fed into the fermentor and at least part of the yeast-free stream is directed into a simple evaporator corresponding to one or several distilling stages where it is separated partially in an ethanol-enriched initial vapour stream supplying a facility to produce the desired ethanol quality, and partially in a liquid initial bottom stream re-fed at least in part into the fermentor. The characteristic feature of this new process is that a raw-material stream is fed into a closed circuit containing the fermentor and the evaporator, and that, in the evaporator, the raw-material stream is hydrolysed to a fermentable state. This hydrolysis is carried out most favourably by enzymes - preferably a gluco-amylase - at a temperature ranging from 35/sup 0/C to 75/sup 0/C.

  19. A comparison of fermentation in the cyanobacterium Microcystis PCC7806 grown under a light/dark cycle and continuous light

    NARCIS (Netherlands)

    Moezelaar, R.; Stal, L.J.

    1997-01-01

    The cyanobacterium Microcystis PCC7806, grown under continuous light, fermented endogenously stored glycogen to equimolar amounts of acetate and ethanol when incubated anaerobically in the dark. In addition, H-2, CO2 and some L-lactate were produced. This fermentation pattern differed from that

  20. Valuable biochemical production in mixed culture fermentation: fundamentals and process coupling.

    Science.gov (United States)

    Dai, Kun; Wen, Jun-Li; Zhang, Fang; Zeng, Raymond J

    2017-08-02

    The mixed culture fermentation is an important environmental biotechnology that converts biodegradable organic wastes to valuable chemicals such as hydrogen, methane, acetate, ethanol, propionate, and so on. For the multistep process of hydrolysis, acidogenesis, acetogenesis/homoacetogensis, and methanogenesis, the typical metabolic reactions are firstly summarized. And then, since the final metabolites are always a mixture, the separation and purification processes are necessary to couple with anaerobic fermentation. Therefore, several typical coupling technologies including biogas upgrading, two-stage fermentation, gas stripping, membrane technology of pervaporation, membrane distillation, electrodialysis, bipolar membrane electrodialysis, and microbial fuel cells are summarized to separate the metabolites and recover energy. At last, the novel technologies such as the controlled metabolite production, medium chain carboxylic acid production, and high temperature ethanol recovery in thermophilic mixed culture fermentation are also reviewed. However, the novel concepts are still needed to meet the demands of better overall performances and lower total costs.

  1. Development of starter culture for improved processing of Lafun, an African fermented cassava food product

    DEFF Research Database (Denmark)

    Padonou, S.W.; Nielsen, Dennis Sandris; Akissoe, N.H.

    2010-01-01

    quality testing showed that Lafun obtained from S. cerevisiae-fermented cassava gave the most preferred stiff porridge. Saccharomyces cerevisiae 2Y48P22 showed pectinase production in a model system. CONCLUSIONS: The results suggest that S. cerevisiae 2Y48P22 is the most efficient organism for cassava...... softening during the fermentation. Therefore, it could be combined with LAB and used as starter for Lafun processing. SIGNIFICANCE AND IMPACT OF THE STUDY: Starter cultures are made available for controlled fermentation of Lafun....

  2. The changes in enzyme activities during citric acid fermentation by Aspergillus niger in solid culture.

    OpenAIRE

    桐村, 光太郎; 熊谷, 和夫; 森貞, 信也; "河邊, 誠一郎"; 宇佐美, 昭次; KOTARO, KIRIMURA; Kazuo, KUMAGAI; SHINYA, MORISADA; Seiichiro", "Kawabe; Shoji, Usami; 住友化学工業株式会社; 岡山理科大学基礎理学科; 早稲田大学理工学部応用化学科; Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University

    1984-01-01

    The changes of enzyme activities during citric acid fermentation in solid culture were studied with a high citric acidproducing strain, Aspergillus niger Yang no. 2,cultivated in synthetic medium containing 2 g/l of gelatin and glass wool as carrier.With fermentation time, the specific activity ratio of fructose-bisphosphate aldolase to glucose-6-phosphate dehydrogenase increased. Of the TCA cycle enzmes, the specific activities of citrate synthetase and aconitate hydratase remained almost co...

  3. Impact of carrier material on fermentative activity of encapsulated yoghurt culture in whey based substrate

    Directory of Open Access Journals (Sweden)

    Krunić Tanja Ž.

    2017-01-01

    Full Text Available The main objectives of this paper were to study the influence of the carrier material used for encapsulation and of bead size to fermentative activity and viability of the dairy starter culture ‘Lactoferm ABY 6’. Encapsulation of yoghurt culture in beads with diameter of 1mm provides better results than encapsulation in beads with larger diameter. Alginate beads and chitosan coated beads have proved to be a strong barrier for nutrients from substrate, so samples with those beads have lower viable cell count, lower titratable acidity and higher pH value after 5h of fermentation at 42°C, than samples with WPC-alginate beads. Also those beads have significantly (P < 0.05 lower cell leaking, than WPC-alginate beads and lower antioxidant capacity. Encapsulation of yoghurt culture in WPC-alginate carrier with diameter of approximately 1mm provided the best characteristics for fermented product. Samples with these beads have significantly (P < 0.05 higher increase of viable cell number after fermentation, despite of major cell leaking (19.7 %. Moreover, sample with these beads have the highest titratable acidity, the lowest pH value after fermentation (the best fermentative activity and the best antioxidant characteristics. [Projekat Ministarstva nauke Republike Srbije, br. TR 31017 i br. III 46010

  4. Application of starter cultures to table olive fermentation: an overview on the experimental studies.

    Science.gov (United States)

    Corsetti, Aldo; Perpetuini, Giorgia; Schirone, Maria; Tofalo, Rosanna; Suzzi, Giovanna

    2012-01-01

    Table olives are one of the oldest fermented foods and are considered as an important component of the Mediterranean diet, since their richness in monounsaturated fats (primarily oleic acid) and phenolic compounds may function as antioxidants in the human body; in the Western world they represent one of the most popular fermented vegetables but, despite its economic significance, table olive fermentation is still craft-based and empirical. In particular, such a type of fermentation results from the competitive activities among indigenous, contaminating microorganisms, the microbial balance depending on several intrinsic (pH, water activity, diffusion of nutrients from the drupe, and level of anti-microbial compounds) and extrinsic (temperature, oxygen availability, and salt concentration) factors. At present, to reduce the risk of spoilage and to achieve a more predictable process there is an increasing interest in developing starter cultures for table olives fermentation. Anyway, the application of starter cultures in the field of table olives is quite far from reaching the diffusion as it has in other sectors of food industry (e.g., dairy products and alcoholic beverages). This review focuses on experimental researches devoted to studying starter cultures for possible application to table olive fermentation both at artisan and industrial level.

  5. Application of starter cultures to table olive fermentation: an overview on the experimental studies

    Directory of Open Access Journals (Sweden)

    Aldo eCorsetti

    2012-07-01

    Full Text Available Table olives are one of the oldest fermented foods and they are considered an important component of the Mediterranean diet, since their richness in monounsaturated fats (primarily oleic acid and phenolic compounds that may function as antioxidants in the human body; in the Western world they represent one of the most popular fermented vegetables but, despite its economic significance, table olive fermentation is still craft-based and empirical. In particular, such a type of fermentation results from the competitive activities among indigenous, contaminating microorganisms, the microbial balance depending on several intrinsic (pH, water activity, diffusion of nutrients from the drupe and level of anti-microbial compounds and extrinsic (temperature, oxygen availability and salt concentration factors. At present, to reduce the risk of spoilage and to achieve a more predictable process there is an increasing interest in developing starter cultures for table olives fermentation. Anyway, the application of starter cultures in the field of table olives is quite far from reaching the diffusion it has in other sectors of food industry (e.g., dairy products and alcoholic beverages. This review focuses on experimental researches devoted to studying starter cultures for possible application to table olive fermentation both at artisan and industrial level.

  6. Application of starter cultures to table olive fermentation: an overview on the experimental studies

    Science.gov (United States)

    Corsetti, Aldo; Perpetuini, Giorgia; Schirone, Maria; Tofalo, Rosanna; Suzzi, Giovanna

    2012-01-01

    Table olives are one of the oldest fermented foods and are considered as an important component of the Mediterranean diet, since their richness in monounsaturated fats (primarily oleic acid) and phenolic compounds may function as antioxidants in the human body; in the Western world they represent one of the most popular fermented vegetables but, despite its economic significance, table olive fermentation is still craft-based and empirical. In particular, such a type of fermentation results from the competitive activities among indigenous, contaminating microorganisms, the microbial balance depending on several intrinsic (pH, water activity, diffusion of nutrients from the drupe, and level of anti-microbial compounds) and extrinsic (temperature, oxygen availability, and salt concentration) factors. At present, to reduce the risk of spoilage and to achieve a more predictable process there is an increasing interest in developing starter cultures for table olives fermentation. Anyway, the application of starter cultures in the field of table olives is quite far from reaching the diffusion as it has in other sectors of food industry (e.g., dairy products and alcoholic beverages). This review focuses on experimental researches devoted to studying starter cultures for possible application to table olive fermentation both at artisan and industrial level. PMID:22833739

  7. Protein improvement in Gari by the use of pure cultures of microorganisms involved in the natural fermentation process.

    Science.gov (United States)

    Ahaotu, I; Ogueke, C C; Owuamanam, C I; Ahaotu, N N; Nwosu, J N

    2011-10-15

    The ability of microorganisms involved in cassava mash fermentation to produce and improve protein value by these microorganisms during fermentation was studied. Standard microbiological procedures were used to isolate, identify and determine the numbers of the organisms. Alcaligenes faecalis, Lactobacillus plantarum, Bacillus subtilis, Leuconostoc cremoris, Aspergillus niger, A. tamari, Geotrichum candidum and Penicillium expansum were isolated and identified from cassava waste water while standard analytical methods were used to determine the ability of the isolates to produce linamarase and the proximate composition, pH and titrable acidity of the fermenting mash. The linamarase activity of the isolates ranged from 0.0416 to 0.2618 micromol mL(-1) nmol(-1). Bacillus subtilis, A. niger, A. tamari and P. expansum did not express any activity for the enzyme. Protein content of mash fermented with mixed fungal culture had the highest protein value (15.4 mg/g/dry matter) while the raw cassava had the least value (2.37 mg/g/dry matter). The naturally fermented sample had the least value for the fermented samples (3.2 mg/g/dry matter). Carbohydrate and fat contents of naturally fermented sample were higher than values obtained from the other fermented samples. Microbial numbers of the sample fermented with mixed bacterial culture was highest and got to their peak at 48 h (57 x 10(8) cfu g(-1)). pH decreased with increase in fermentation time with the mash fermented by the mixed culture of fungi having the lowest pH of 4.05 at the end of fermentation. Titrable acidity increased with increase in fermentation time with the highest value of 1.32% at 96 h of fermentation produced by the mixed culture of fungi. Thus fermentation with the pure cultures significantly increased the protein content of mash.

  8. Microbiological study of lactic acid fermentation of Caper berries by molecular and culture-dependent methods.

    Science.gov (United States)

    Pérez Pulido, Rubén; Ben Omar, Nabil; Abriouel, Hikmate; Lucas López, Rosario; Martínez Cañamero, Magdalena; Gálvez, Antonio

    2005-12-01

    Fermentation of capers (the fruits of Capparis sp.) was studied by molecular and culture-independent methods. A lactic acid fermentation occurred following immersion of caper berries in water, resulting in fast acidification and development of the organoleptic properties typical of this fermented food. A collection of 133 isolates obtained at different times of fermentation was reduced to 75 after randomly amplified polymorphic DNA (RAPD)-PCR analysis. Isolates were identified by PCR or 16S rRNA gene sequencing as Lactobacillus plantarum (37 isolates), Lactobacillus paraplantarum (1 isolate), Lactobacillus pentosus (5 isolates), Lactobacillus brevis (9 isolates), Lactobacillus fermentum (6 isolates), Pediococcus pentosaceus (14 isolates), Pediococcus acidilactici (1 isolate), and Enterococcus faecium (2 isolates). Cluster analysis of RAPD-PCR patterns revealed a high degree of diversity among lactobacilli (with four major groups and five subgroups), while pediococci clustered in two closely related groups. A culture-independent analysis of fermentation samples by temporal temperature gradient electrophoresis (TTGE) also indicated that L. plantarum is the predominant species in this fermentation, in agreement with culture-dependent results. The distribution of L. brevis and L. fermentum in samples was also determined by TTGE, but identification of Pediococcus at the species level was not possible. TTGE also allowed a more precise estimation of the distribution of E. faecium, and the detection of Enterococcus casseliflavus (which was not revealed by the culture-dependent analysis). Results from this study indicate that complementary data from molecular and culture-dependent analysis provide a more accurate determination of the microbial community dynamics during caper fermentation.

  9. Effect of lactic acid bacteria starter culture fermentation of cassava ...

    African Journals Online (AJOL)

    The values of the sugar, starch and amylose contents show similar trends. The sugar contents ranges between 5.21 ± 0.04 to 4.41 ± 0.0%, with the unfermented sample having the highest value. When subjected to sensory evaluation, the traditional and starterculture fermented cassava fufu flour were not significantly ...

  10. EFFECT OF FERMENTATION BY MIXED CULTURES OF LACTIC

    African Journals Online (AJOL)

    Unfermented tef atmir as a weaning food may not be necessarily beneficial for iron and zinc bio-availability. ... Fermentation is known to reduce phytic acid content of several plant foods including rice, corn, millet, ..... and may further lead to a better mineral status of the vegetarian population where animal products are not.

  11. Continuous immobilized yeast reactor system for complete beer fermentation using spent grains and corncobs as carrier materials.

    Science.gov (United States)

    Brányik, Tomás; Silva, Daniel P; Vicente, António A; Lehnert, Radek; e Silva, João B Almeida; Dostálek, Pavel; Teixeira, José A

    2006-12-01

    Despite extensive research carried out in the last few decades, continuous beer fermentation has not yet managed to outperform the traditional batch technology. An industrial breakthrough in favour of continuous brewing using immobilized yeast could be expected only on achievement of the following process characteristics: simple design, low investment costs, flexible operation, effective process control and good product quality. The application of cheap carrier materials of by-product origin could significantly lower the investment costs of continuous fermentation systems. This work deals with a complete continuous beer fermentation system consisting of a main fermentation reactor (gas-lift) and a maturation reactor (packed-bed) containing yeast immobilized on spent grains and corncobs, respectively. The suitability of cheap carrier materials for long-term continuous brewing was proved. It was found that by fine tuning of process parameters (residence time, aeration) it was possible to adjust the flavour profile of the final product. Consumers considered the continuously fermented beer to be of a regular quality. Analytical and sensorial profiles of both continuously and batch fermented beers were compared.

  12. Identification of predominant yeasts associated with artisan Mexican cocoa fermentations using culture-dependent and culture-independent approaches.

    Science.gov (United States)

    Arana-Sánchez, A; Segura-García, L E; Kirchmayr, M; Orozco-Ávila, I; Lugo-Cervantes, E; Gschaedler-Mathis, A

    2015-02-01

    The process of cocoa fermentation is a very important step for the generation or aromatic compounds, which are attributable to the metabolism of the microorganisms involved. There are some reports about this process and the identification of microorganisms; however, there are no reports identifying the yeasts involved in a Mexican cocoa fermentation process using molecular biology techniques, including restricted fragment length polymorphism (RFLP) and denaturing gradient gel electrophoresis (DGGE). The aim of this study was to identify the main yeast species associated with Mexican cocoa fermentations employing culture-dependent and -independent techniques achieving two samplings with a 1 year time difference at the same site. Isolation of the microorganisms was performed in situ. Molecular identification of yeast isolates was achieved by RFLP analysis and rDNA sequencing. Total DNA from the microorganisms on the cocoa beans was utilized for the DGGE analysis. Bands from the DGGE gels were excised and sequenced. Nineteen isolated yeasts were identified (al specie level), three of which had never before been associated with cocoa fermentations worldwide. The detected predominant yeast varied from one technique to another. Hanseniaspora sp. resulted dominant in DGGE however Saccharomyces cerevisiae was the principal isolated species. In conclusion, the culture-dependent and -independent techniques complement each other showing differences in the main yeasts involved in spontaneous cocoa fermentation, probably due to the physiological states of the viable but non culturable yeasts. Furthermore important differences between the species detected in the two samplings were detected.

  13. Characteristic of fermented spinach (Amaranthus spp.) polyphenol by kombucha culture for antioxidant compound

    Science.gov (United States)

    Aspiyanto, Susilowati, Agustine; Iskandar, Jeti M.; Melanie, Hakiki; Maryati, Yati; Lotulung, Puspa D.

    2017-01-01

    Fermentation on spinach (Amaranthus sp.) vegetable by kombucha culture as an effort to get poliphenol as antioxidant compound had been done. Purification of fermented spinach extract suspension was carried out through microfiltration (MF) membrane (pore size 0.15 µm) fitted in dead-end Stirred Ultrafiltration Cell (SUFC) mode at fixed condition (stirrer rotation 400 rpm, room temperature, pressure 40 psia). Result of the experimental activity showed that long fermentation time increased total acids, total polyphenol and Total Plate Count (TPC), and decreased total solids and reducing sugar in biomass. The optimal fermentation time was reached for 2 weeks with total polyphenol recovery increasing of 92.76 % from before and after fermentation. On this optimal fermentation time, biomass had identified galic acid with relative intensity of 8 %, while as polyphenol monomer was resulted 5 kinds of polyphenol compounds with total intensity 27.97 % and molecular weight (MW) 191.1736, 193.1871 and 194.2170 at T2.5, T2.86 and T3.86. Long fermentation time increased functional properties of polyphenol as antioxidant.

  14. Regulation of alcoholic fermentation in batch and chemostat cultures of Kluyveromyces lactis CBS 2359.

    Science.gov (United States)

    Kiers, J; Zeeman, A M; Luttik, M; Thiele, C; Castrillo, J I; Steensma, H Y; van Dijken, J P; Pronk, J T

    1998-03-30

    Kluyveromyces lactis is an important industrial yeast, as well as a popular laboratory model. There is currently no consensus in the literature on the physiology of this yeast, in particular with respect to aerobic alcoholic fermentation ('Crabtree effect'). This study deals with regulation of alcoholic fermentation in K. lactis CBS 2359, a proposed reference strain for molecular studies. In aerobic, glucose-limited chemostate cultures (D = 0.05-0.40 h-1) growth was entirely respiratory, without significant accumulation of ethanol or other metabolities. Alcoholic fermentation occurred in glucose-grown shake-flask cultures, but was absent during batch cultivation on glucose in fermenters under strictly aerobic conditions. This indicated that ethanol formation in the shake-flask cultures resulted from oxygen limitation. Indeed, when the oxygen feed to steady-state chemostat cultures (D = 0.10 h-1) was lowered, a mixed respirofermentative metabolism only occurred at very low dissolved oxygen concentrations (less than 1% of air saturation). The onset of respirofermentative metabolism as a result of oxygen limitation was accompanied by an increase of the levels of pyruvate decarboxylase and alcohol dehydrogenase. When aerobic, glucose-limited chemostat cultures (D = 0.10 h-1) were pulsed with excess glucose, ethanol production did not occur during the first 40 min after the pulse. However, a slow aerobic ethanol formation was invariably observed after this period. Since alcoholic fermentation did not occur in aerobic batch cultures this is probably a transient response, caused by an imbalanced adjustment of enzyme levels during the transition from steady-state growth at mu = 0.10 h to growth at mu max. It is concluded that in K. lactis, as in other Crabtree-negative yeasts, the primary environmental trigger for occurrence of alcoholic fermentation is oxygen limitation.

  15. Fermentation of model hemicelluloses by Prevotella strains and Butyrivibrio fibrisolvens in pure culture and in ruminal enrichment cultures.

    Science.gov (United States)

    Emerson, Elianna L; Weimer, Paul J

    2017-05-01

    Hemicelluloses are major components of plant biomass, but their fermentation in the rumens of cattle and other ruminants is poorly understood. We compared four species of the ruminally dominant genus Prevotella and the well-known hemicellulose utilizer, Butyrivibrio fibrisolvens, with respect to degradation of several isolated hemicelluloses (xylans, glucomannan, and xyloglucan). We also performed Illumina sequencing of the V3/V4 region of 16S rRNA genes to determine the relative proportions of Prevotella and Butyrivibrio in hemicellulose-fed enrichment cultures inoculated from ruminal contents of dairy cattle fed a total mixed ration (TMR) rich in hemicelluloses. Results confirmed the xylan fermentation and butyrate production abilities of B. fibrisolvens. Despite their reputation as generalist fermenters, the Prevotella strains poorly fermented these hemicelluloses but exhibited dramatic differences in fermentation end products. Prevotella was much less abundant in mixed bacterial enrichment cultures fed the same TMR than in the ruminal inoculum, yet Prevotella was again the most abundant genus in enrichment cultures fed xylans. By contrast, glucomannan fermentations were dominated by Streptococcus sp. Genera known for hemicellulose degradation (Butyrivibrio, Ruminococcus, and Fibrobacter) were not significantly enriched on these hemicelluloses. Substantial differences in fermentation end product distribution from the different hemicelluloses were observed, which would likely affect nutrient partitioning in the host animal. Differences in community composition between in vitro hemicellulose enrichments and inoculum samples emerged at every phylogenetic level, suggesting that in vitro conditions provide unique selective pressures on the bacterial community and also that ruminal bacteria exhibit specialization with respect to hemicellulose utilization.

  16. Impact of a Microbial Cocktail Used as a Starter Culture on Cocoa Fermentation and Chocolate Flavor

    Directory of Open Access Journals (Sweden)

    Igor Magalhães da Veiga Moreira

    2017-05-01

    Full Text Available Chocolate production suffered a vast impact with the emergence of the “witches’ broom” disease in cocoa plants. To recover cocoa production, many disease-resistant hybrid plants have been developed. However, some different cocoa hybrids produce cocoa beans that generate chocolate with variable quality. Fermentation of cocoa beans is a microbiological process that can be applied for the production of chocolate flavor precursors, leading to overcoming the problem of variable chocolate quality. The aim of this work was to use a cocktail of microorganisms as a starter culture on the fermentation of the ripe cocoa pods from PH15 cocoa hybrid, and evaluate its influence on the microbial communities present on the fermentative process on the compounds involved during the fermentation, and to perform the chocolate sensorial characterization. According to the results obtained, different volatile compounds were identified in fermented beans and in the chocolate produced. Bitterness was the dominant taste found in non-inoculated chocolate, while chocolate made with inoculated beans showed bitter, sweet, and cocoa tastes. 2,3-Butanediol and 2,3-dimethylpyrazine were considered as volatile compounds making the difference on the flavor of both chocolates. Saccharomyces cerevisiae UFLA CCMA 0200, Lactobacillus plantarum CCMA 0238, and Acetobacter pasteurianus CCMA 0241 are proposed as starter cultures for cocoa fermentation.

  17. Impact of a Microbial Cocktail Used as a Starter Culture on Cocoa Fermentation and Chocolate Flavor.

    Science.gov (United States)

    Magalhães da Veiga Moreira, Igor; de Figueiredo Vilela, Leonardo; da Cruz Pedroso Miguel, Maria Gabriela; Santos, Cledir; Lima, Nelson; Freitas Schwan, Rosane

    2017-05-09

    Chocolate production suffered a vast impact with the emergence of the "witches' broom" disease in cocoa plants. To recover cocoa production, many disease-resistant hybrid plants have been developed. However, some different cocoa hybrids produce cocoa beans that generate chocolate with variable quality. Fermentation of cocoa beans is a microbiological process that can be applied for the production of chocolate flavor precursors, leading to overcoming the problem of variable chocolate quality. The aim of this work was to use a cocktail of microorganisms as a starter culture on the fermentation of the ripe cocoa pods from PH15 cocoa hybrid, and evaluate its influence on the microbial communities present on the fermentative process on the compounds involved during the fermentation, and to perform the chocolate sensorial characterization. According to the results obtained, different volatile compounds were identified in fermented beans and in the chocolate produced. Bitterness was the dominant taste found in non-inoculated chocolate, while chocolate made with inoculated beans showed bitter, sweet, and cocoa tastes. 2,3-Butanediol and 2,3-dimethylpyrazine were considered as volatile compounds making the difference on the flavor of both chocolates. Saccharomyces cerevisiae UFLA CCMA 0200, Lactobacillus plantarum CCMA 0238, and Acetobacter pasteurianus CCMA 0241 are proposed as starter cultures for cocoa fermentation.

  18. Identification of Dekkera bruxellensis as a major contaminant yeast in continuous fuel ethanol fermentation.

    Science.gov (United States)

    de Souza Liberal, A T; Basílio, A C M; do Monte Resende, A; Brasileiro, B T V; da Silva-Filho, E A; de Morais, J O F; Simões, D A; de Morais, M A

    2007-02-01

    To identify and characterize the main contaminant yeast species detected in fuel-ethanol production plants in Northeast region of Brazil by using molecular methods. Total DNA from yeast colonies isolated from the fermentation must of industrial alcohol plants was submitted to PCR fingerprinting, D1/D2 28S rDNA sequencing and species-specific PCR analysis. The most frequent non-Saccharomyces cerevisiae isolates were identified as belonging to the species Dekkera bruxellensis, and several genetic strains could be discriminated among the isolates. The yeast population dynamics was followed on a daily basis during a whole crop harvesting period in a particular industry, showing the potential of D. bruxellensis to grow faster than S. cerevisiae in industrial conditions, causing recurrent and severe contamination episodes. The results showed that D. bruxellensis is one of the most important contaminant yeasts in distilleries producing fuel-ethanol from crude sugar cane juice, specially in continuous fermentation systems. Severe contamination of the industrial fermentation process by Dekkera yeasts has a negative impact on ethanol yield and productivity. Therefore, early detection of D. bruxellensis in industrial musts may avoid operational problems in alcohol-producing plants.

  19. Enhanced Aspergillus ficuum phytase production in fed-batch and continuous fermentations in the presence of talcum microparticles.

    Science.gov (United States)

    Coban, Hasan B; Demirci, Ali; Turhan, Irfan

    2015-08-01

    This study aimed to enhance Aspergillus ficuum phytase production in fed-batch and continuous fermentations with addition of talcum microparticles. Phytase activity almost doubled in fed-batch and continuous fermentations by addition of 15 g/l of talcum compared to the control. Effect of talcum on fungal morphology was also shown that addition of talcum provided smaller fungal pellets and more homogenized fermentation broth compared to the control. Average fungal pellet radius decreased from 500 to 100 µm by addition of 15 g/l of talcum in the bioreactors. Also, 15 g/l talcum addition increased phytase productivity and optimum dilution rate in the continuous fermentations from 0.293 to 0.621 U/ml/h and from 0.09 to 0.1/h, respectively, compared to control.

  20. Enhanced hydrogen and 1,3-propanediol production from glycerol by fermentation using mixed cultures

    KAUST Repository

    Selembo, Priscilla A.

    2009-12-15

    The conversion of glycerol into high value products, such as hydrogen gas and 1,3-propanediol (PD), was examined using anaerobic fermentation with heat-treated mixed cultures. Glycerol fermentation produced 0.28 mol-H 2/mol-glycerol (72 mL-H2/g-COD) and 0.69 mol-PD/mol-glycerol. Glucose fermentation using the same mixed cultures produced more hydrogen gas (1.06 mol-H2/mol-glucose) but no PD. Changing the source of inoculum affected gas production likely due to prior acclimation of bacteria to this type of substrate. Fermentation of the glycerol produced from biodiesel fuel production (70% glycerol content) produced 0.31 mol-H 2/mol-glycerol (43 mL H2/g-COD) and 0.59 mol-PD/mol-glycerol. These are the highest yields yet reported for both hydrogen and 1,3-propanediol production from pure glycerol and the glycerol byproduct from biodiesel fuel production by fermentation using mixed cultures. These results demonstrate that production of biodiesel can be combined with production of hydrogen and 1,3-propanediol for maximum utilization of resources and minimization of waste. © 2009 Wiley Periodicals, Inc.

  1. Preparation of a Lactobacillus plantarum starter culture for cucumber fermentations that can meet kosher guidelines.

    Science.gov (United States)

    Pérez-Díaz, I M; McFeeters, R F

    2011-03-01

    A method is described for growth of a Lactobacillus plantarum starter culture in jars of commercially available pasteurized fresh-pack kosher dill cucumbers so that jars can be used to inoculate commercial scale cucumber fermentation tanks. A procedure is also described to transfer lactic acid bacteria from frozen storage in MRS broth into cucumber juice and commercial jars of kosher dill cucumbers so that a selected strain of lactic acid bacteria can be kosher certified for commercial fermentations in processing plants that operate under kosher certification. The strain of L. plantarum used in these experiments grew to maximum cell numbers in 4 d at 20 to 25 °C and then maintained viable cell numbers for 2 wk at >10(8) CFU/mL so the culture was suitable for inoculation of fermentation tanks. Refrigeration of jars of culture after they grow to maximum numbers minimizes die-off of cells sufficiently so that a pure culture can be maintained by aseptically transferring brine containing viable bacteria to a new pH-adjusted jar only once every 4 mo. This report describes a method to prepare a lactic acid bacteria starter culture suitable for kosher vegetable fermentations.

  2. Continuous acetone-ethanol-butanol fermentation by immobilized cells of Clostridium acetobutylicum

    Energy Technology Data Exchange (ETDEWEB)

    Badr, H.R.; Toledo, R.; Hamdy, M.K. [University of Georgia, Athens (Greece). Food Science and Technology Dept.

    2001-07-01

    Eight Clostridium acetobutylicum strains were examined for {alpha}-amylase and strains B-591, B-594 and P-262 had the highest activities. Defibered-sweet-potato-slurry (DSPS), containing 39.7 g starch l{sup -1}, supplemented with potassium phosphate (1.0 g l{sup -1}), cysteine-HCl (5.0 g l{sup -1}), the antifoam (polypropylene glycol, 0.1 mg ml{sup -1}), was used a continuous feedstock (FS) to a multistage bioreactor system for acetone-ethanol-butanol (AEB) fermentation. The system consisted on four columns (three vertical and one near horizontal) packed with beads containing immobilized cells of C. acetobutylicum P-262. When DSPS was pumped into the bioreactor system, at a flow rate of 2.36 ml min{sup -1}, the effluent has 7.73 g solvents l{sup -1} (1.56, acetone; 0.65, ethanol; 5.52 g, butanol) and no starch. Productivity of total solvents synthesized during continuous operation were 1.0 g 1{sup -1}h{sup -1} and 19.5 % yield compared to 0.12 g l{sup -1}h{sup -1} with 29% yield using the batch system. We proposed using DSPS for AEB fermentation in a continuous mode with immobilized P-262 cells that are active amylase producers which will lead to cost reduction compared to the batch system. (Author)

  3. Starter Culture Selection for Making Chinese Sesame-Flavored Liquor Based on Microbial Metabolic Activity in Mixed-Culture Fermentation

    Science.gov (United States)

    Wu, Qun; Ling, Jie

    2014-01-01

    Selection of a starter culture with excellent viability and metabolic activity is important for inoculated fermentation of traditional food. To obtain a suitable starter culture for making Chinese sesame-flavored liquor, the yeast and bacterium community structures were investigated during spontaneous and solid-state fermentations of this type of liquor. Five dominant species in spontaneous fermentation were identified: Saccharomyces cerevisiae, Pichia membranaefaciens, Issatchenkia orientalis, Bacillus licheniformis, and Bacillus amyloliquefaciens. The metabolic activity of each species in mixed and inoculated fermentations of liquor was investigated in 14 different cocultures that used different combinations of these species. The relationships between the microbial species and volatile metabolites were analyzed by partial least-squares (PLS) regression analysis. We found that S. cerevisiae was positively correlated to nonanal, and B. licheniformis was positively associated with 2,3-butanediol, isobutyric acid, guaiacol, and 4-vinyl guaiacol, while I. orientalis was positively correlated to butyric acid, isovaleric acid, hexanoic acid, and 2,3-butanediol. These three species are excellent flavor producers for Chinese liquor. Although P. membranaefaciens and B. amyloliquefaciens were not efficient flavor producers, the addition of them alleviated competition among the other three species and altered their growth rates and flavor production. As a result, the coculture of all five dominant species produced the largest amount of flavor compounds. The result indicates that flavor producers and microbial interaction regulators are important for inoculated fermentation of Chinese sesame-flavored liquor. PMID:24814798

  4. Biohydrogen production from wheat straw hydrolysate by dark fermentation using extreme thermophilic mixed culture.

    Science.gov (United States)

    Kongjan, Prawit; O-Thong, Sompong; Kotay, Meher; Min, Booki; Angelidaki, Irini

    2010-04-01

    Hydrolysate was tested as substrate for hydrogen production by extreme thermophilic mixed culture (70 degrees C) in both batch and continuously fed reactors. Hydrogen was produced at hydrolysate concentrations up to 25% (v/v), while no hydrogen was produced at hydrolysate concentration of 30% (v/v), indicating that hydrolysate at high concentrations was inhibiting the hydrogen fermentation process. In addition, the lag phase for hydrogen production was strongly influenced by the hydrolysate concentration, and was prolonged from approximately 11 h at the hydrolysate concentrations below 20% (v/v) to 38 h at the hydrolysate concentration of 25% (v/v). The maximum hydrogen yield as determined in batch assays was 318.4 +/- 5.2 mL-H(2)/g-sugars (14.2 +/- 0.2 mmol-H(2)/g-sugars) at the hydrolysate concentration of 5% (v/v). Continuously fed, and the continuously stirred tank reactor (CSTR), operating at 3 day hydraulic retention time (HRT) and fed with 20% (v/v) hydrolysate could successfully produce hydrogen. The hydrogen yield and production rate were 178.0 +/- 10.1 mL-H(2)/g-sugars (7.9 +/- 0.4 mmol H(2)/g-sugars) and 184.0 +/- 10.7 mL-H(2)/day L(reactor) (8.2 +/- 0.5 mmol-H(2)/day L(reactor)), respectively, corresponding to 12% of the chemical oxygen demand (COD) from sugars. Additionally, it was found that toxic compounds, furfural and hydroxymethylfurfural (HMF), contained in the hydrolysate were effectively degraded in the CSTR, and their concentrations were reduced from 50 and 28 mg/L, respectively, to undetectable concentrations in the effluent. Phylogenetic analysis of the mixed culture revealed that members involved hydrogen producers in both batch and CSTR reactors were phylogenetically related to the Caldanaerobacter subteraneus, Thermoanaerobacter subteraneus, and Thermoanaerobacterium thermosaccharolyticum. (c) 2009 Wiley Periodicals, Inc.

  5. Culture independent methods to assess the diversity and dynamics of microbiota during food fermentation.

    Science.gov (United States)

    Cocolin, Luca; Alessandria, Valentina; Dolci, Paola; Gorra, Roberta; Rantsiou, Kalliopi

    2013-10-01

    Culture independent methods first appeared in the food microbiology field at the end of the 90s and since then they have been applied extensively. These methods do not rely on cultivation and target nucleic acids (DNA and RNA) to identify and follow the changes that occur in the main populations present in a specific ecosystem. The method that has most often been used as a culture independent method in food microbiology is denaturing gradient gel electrophoresis (DGGE). The number of papers dealing with DGGE grew exponentially in the late nineties and, by analysing the studies available in the literature, it is possible to describe a trend in the subjects that have been investigated. DGGE was first used as a tool to monitor the ecology of fermented food, such as fermented sausage, cheese and sourdough, and later it also showed its potential in microbial spoilage process. In the last few years, the main application of DGGE has been to study fermented food from Asia, Africa and South America. The information collected using DGGE has made it possible to confirm the existing knowledge on food fermentation and spoilage. However, in some cases, new evidence that helps scientists to fully comprehend a specific microbial ecosystem has emerged. In this review, the roadmap of culture independent methods in food microbiology will be summarized, focusing on the DGGE technique. Examples of how this approach is useful to obtain a better understanding of microbial diversity are reported for several kinds of fermented food, such as fermented sausage, cheese and wine. The future of culture independent methods in food microbiology, with the increasing availability of next generation sequencing techniques, is also discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Production of Solvent (acetone-butanol-ethanol in Continuous Fermentation by Clostridium saccharobutylicum DSM 13864 Using Gelatinised Sago Starch as a Carbon Source

    Directory of Open Access Journals (Sweden)

    Liew, S. T.

    2006-01-01

    Full Text Available Solvent production by Clostridium saccharobutylicum DSM 13864 was carried out in a single stage continuous culture using 2 L stirred tank fermenter with gelatinised sago starch as a carbon source. From the study it was found that the condition could be adjusted to suit for acids production (high dilution rate and high pH or solvent production (low dilution rate and low pH by manipulating the dilution rate and culture pH of single stage continuous fermentation. The highest solvent concentration in outflow (9.10 g/L was obtained at pH 4.5 and dilution rate of 0.05 h^1, which corresponds to overall productivity of 0.46 g/L.h. However, the highest total solvent productivity (0.85 g/L.h was obtained at dilution rate of 0.11 h-1 and pH 4.5, which gave a total solvent yield of 0.29 g solvent/g sago starch. Although the total solvent productivity was greatly increased in continuous culture, the final solvent concentration attained in outflow was decreased by about 53% as compared to batch culture.

  7. Culture-dependent and -independent methods to investigate the microbial ecology of Italian fermented sausages.

    Science.gov (United States)

    Rantsiou, Kalliopi; Urso, Rosalinda; Iacumin, Lucilla; Cantoni, Carlo; Cattaneo, Patrizia; Comi, Giuseppe; Cocolin, Luca

    2005-04-01

    In this study, the microbial ecology of three naturally fermented sausages produced in northeast Italy was studied by culture-dependent and -independent methods. By plating analysis, the predominance of lactic acid bacteria populations was pointed out, as well as the importance of coagulase-negative cocci. Also in the case of one fermentation, the fecal enterocci reached significant counts, highlighting their contribution to the particular transformation process. Yeast counts were higher than the detection limit (> 100 CFU/g) in only one fermented sausage. Analysis of the denaturing gradient gel electrophoresis (DGGE) patterns and sequencing of the bands allowed profiling of the microbial populations present in the sausages during fermentation. The bacterial ecology was mainly characterized by the stable presence of Lactobacillus curvatus and Lactobacillus sakei, but Lactobacillus paracasei was also repeatedly detected. An important piece of evidence was the presence of Lactococcus garvieae, which clearly contributed in two fermentations. Several species of Staphylococcus were also detected. Regarding other bacterial groups, Bacillus sp., Ruminococcus sp., and Macrococcus caseolyticus were also identified at the beginning of the transformations. In addition, yeast species belonging to Debaryomyces hansenii, several Candida species, and Willopsis saturnus were observed in the DGGE gels. Finally, cluster analysis of the bacterial and yeast DGGE profiles highlighted the uniqueness of the fermentation processes studied.

  8. Unraveling microbial ecology of industrial-scale Kombucha fermentations by metabarcoding and culture-based methods.

    Science.gov (United States)

    Coton, Monika; Pawtowski, Audrey; Taminiau, Bernard; Burgaud, Gaëtan; Deniel, Franck; Coulloumme-Labarthe, Laurent; Fall, Abdoulaye; Daube, Georges; Coton, Emmanuel

    2017-05-01

    Kombucha, historically an Asian tea-based fermented drink, has recently become trendy in Western countries. Producers claim it bears health-enhancing properties that may come from the tea or metabolites produced by its microbiome. Despite its long history of production, microbial richness and dynamics have not been fully unraveled, especially at an industrial scale. Moreover, the impact of tea type (green or black) on microbial ecology was not studied. Here, we compared microbial communities from industrial-scale black and green tea fermentations, still traditionally carried out by a microbial biofilm, using culture-dependent and metabarcoding approaches. Dominant bacterial species belonged to Acetobacteraceae and to a lesser extent Lactobacteriaceae, while the main identified yeasts corresponded to Dekkera, Hanseniaspora and Zygosaccharomyces during all fermentations. Species richness decreased over the 8-day fermentation. Among acetic acid bacteria, Gluconacetobacter europaeus, Gluconobacter oxydans, G. saccharivorans and Acetobacter peroxydans emerged as dominant species. The main lactic acid bacteria, Oenococcus oeni, was strongly associated with green tea fermentations. Tea type did not influence yeast community, with Dekkera bruxellensis, D. anomala, Zygosaccharomyces bailii and Hanseniaspora valbyensis as most dominant. This study unraveled a distinctive core microbial community which is essential for fermentation control and could lead to Kombucha quality standardization. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. [Continuous dry fermentation of pig manure using up plug-flow type anaerobic reactor].

    Science.gov (United States)

    Chen, Chuang; Deng, Liang-Wei; Xin, Xin; Zheng, Dan; Liu, Yi; Kong, Chui-Xue

    2012-03-01

    To solve the problems of ammonia inhibition and discharging difficulty in continuous dry fermentation of pig manure, under the experimental conditions of temperature of (25 +/- 2) degrees C and organic loading rate (TS) of 4.44 g x (L x d) (-1), a lab-scale up plug-flow type anaerobic reactor (UPAR) was setup to investigate biogas production, ammonia inhibition, effluent liquidity, and the feasibility of continuous dry fermentation of pig manure using up plug-flow type anaerobic reactor. The experiment was operated for 160 days using the pig manure with four different TS mass fractions (20%, 25%, 30%, 35%) as feeding. Results showed that the feeding TS mass fraction exerted a significant influence on the dry fermentation of pig manure; the stable volumetric biogas production rates of four different feeding TS mass fractions were 2.40, 1.73, 0.89, and 0.62 L x (L x d)(-1), respectively; the biogas producing efficiencies of the reactors with feeding TS mass fractions of 20%, 25% and 30% were obviously superior to that with feeding TS of 35%. With feeding TS mass fraction increased from 20% to 35%, obvious inhibition to biogas producing occurred when concentration of ammonia nitrogen reached more than 2 300 mg x L(-1). When the feeding TS mass fraction was 35%, the concentration of ammonia nitrogen could accumulate to 3 800 mg x L(-1) but biogas production rate decreased 74.1% of that with feeding TS of 20%. Additionally, while the feeding TS mass fraction was 35%, the effluent TS mass fraction achieved 17.1%, and the velocity of effluent was less than 0.002 m x s(-1) the effluent of UPAR could not be smoothly discharged.

  10. Impact of sequential co-culture fermentations on flavour characters of Solaris wines

    DEFF Research Database (Denmark)

    Liu, Jing; Arneborg, Nils; Toldam-Andersen, Torben Bo

    2017-01-01

    -phenylethyl acetate. This co-culture fermentation also produced higher amounts of ethyl acetate and acetic acid, reducing the possibility of its use in winemaking. Three Metschnikowia strains, a M. chrysoperlae strain and two M. fructicola strains, gave a comparable production of volatile compounds...

  11. Selective carboxylate production by controlling hydrogen, carbon dioxide and substrate concentrations in mixed culture fermentation

    NARCIS (Netherlands)

    Arslan, D.; Steinbusch, K.J.J.; Diels, L.; Wever, de H.; Hamelers, H.V.M.; Buisman, C.J.N.

    2013-01-01

    This research demonstrated the selective production of n-butyrate from mixed culture by applying 2 bar carbon dioxide into the headspace of batch fermenters or by increasing the initial substrate concentration. The effect of increasing initial substrate concentration was investigated at 8, 13.5 and

  12. Mixed culture syngas fermentation and conversion of carboxylic acids into alcohols.

    Science.gov (United States)

    Liu, Kan; Atiyeh, Hasan K; Stevenson, Bradley S; Tanner, Ralph S; Wilkins, Mark R; Huhnke, Raymond L

    2014-01-01

    Higher alcohols such as n-butanol and n-hexanol have higher energy density than ethanol, are more compatible with current fuel infrastructure, and can be upgraded to jet and diesel fuels. Several organisms are known to convert syngas to ethanol, but very few can produce higher alcohols alone. As a potential solution, mixed culture fermentation between the syngas fermenting Alkalibaculum bacchi strain CP15 and propionic acid producer Clostridium propionicum was studied. The monoculture of CP15 produced only ethanol from syngas without initial addition of organic acids to the fermentation medium. However, the mixed culture produced ethanol, n-propanol and n-butanol from syngas. The addition of propionic acid, butyric acid and hexanoic acid to the mixed culture resulted in a 50% higher conversion efficiency of these acids to their respective alcohols compared to CP15 monoculture. These findings illustrate the great potential of mixed culture syngas fermentation in production of higher alcohols. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Effect of hydrogen and carbon dioxide on carboxylic acids patterns in mixed culture fermentation

    NARCIS (Netherlands)

    Arslan, D.; Steinbusch, K.J.J.; Diels, L.; Wever, De H.; Buisman, C.J.N.; Hamelers, H.V.M.

    2012-01-01

    This study investigated the carboxylate spectrum from mixed culture fermentation of three organic waste streams after supplying 2 bar hydrogen and carbon dioxide or a mixture of these two gases to the headspace. Under any modified headspace, propionate production was ceased and butyrate, caproate

  14. Dichloromethane Fermentation by a Dehalobacter sp. in an Enrichment Culture Derived from Pristine River Sediment

    Science.gov (United States)

    Justicia-Leon, Shandra D.; Ritalahti, Kirsti M.; Mack, E. Erin

    2012-01-01

    Dichloromethane (DCM) as the sole substrate supported growth of a Dehalobacter sp. in an enrichment culture derived from noncontaminated river sediment. DCM was not reductively dechlorinated, and acetate was produced, indicating DCM fermentation and further suggesting Dehalobacter growth is not limited to organohalide respiration. PMID:22179245

  15. Exploring the selective lactic acid production from food waste in uncontrolled pH mixed culture fermentations using different reactor configurations.

    Science.gov (United States)

    Bonk, Fabian; Bastidas-Oyanedel, Juan-Rodrigo; Yousef, Ahmed F; Schmidt, Jens Ejbye

    2017-08-01

    Carboxylic acid production from food waste by mixed culture fermentation is an important future waste management option. Obstacles for its implementation are the need of pH control, and a broad fermentation product spectrum leading to increased product separation costs. To overcome these obstacles, the selective production of lactic acid (LA) from model food waste by uncontrolled pH fermentation was tested using different reactor configurations. Batch experiments, semi-continuously fed reactors and a percolation system reached LA concentrations of 32, 16 and 15gCODLA/L, respectively, with selectivities of 93%, 84% and 75% on COD base, respectively. The semi-continuous reactor was dominated by Lactobacillales. Our techno-economic analysis suggests that LA production from food waste can be economically feasible, with LA recovery and low yields remaining as major obstacles. To solve both problems, we successfully applied in-situ product extraction using activated carbon. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Effect of starter cultures combinations on lipolytic activity and ripening of dry fermented sausages

    Directory of Open Access Journals (Sweden)

    Enver Baris Bingol

    2014-11-01

    Full Text Available The effect of starter culture combinations on the quality of Turkish type dry fermented sausage (sucuk were evaluated during ripening and storage periods. Sucuk formulations were produced without (control and with three different starter culture combinations; i Staphylococcus carnosus+Pediococcus pentosaceus, ii Staphylococcus carnosus+ Lactobacillus sakei, and iii Staphylococcus carnosus+Pediococcus pentosaceus+Lactobacillus sakei. Analysis of microbiological, physico-chemical and lipase enzyme levels of samples were conducted until the 60th day. Interactions among the presence of lipolytic starter cultures, lipase enzyme levels and thiobarbituric acid reactive substances were also evaluated both in ripening and drying periods. There were apparent differences on microbiological and chemical properties between samples prepared with starters and control. It has been concluded that the use of lipolytic starter cultures in suitable combination would have positive effect on the acceleration of ripening and improvement of the quality of dry fermented sausages.

  17. Density of bacteria in Limnodrilus sp. culture fertilized by fermented chicken manure

    Directory of Open Access Journals (Sweden)

    Y. Hadiroseyani

    2007-01-01

    Full Text Available Culture of Limnodrilus sp. is now developed to control continuously supply.  Culture medium of Limnodrilus sp. consists of mud and organic waste.  Routinely fertilization is needed to keep enough nutrition.  One of organic fertilizer used in Limnodrilus sp. culture is chicken manure.  This fertilizer contains high levels of N, low-priced and easy to obtain.  This study was conducted to determine Limnodrilus sp. density in the substrate fertilizer by fermented chicken manure and Limnodrilus sp. growth. Mud and chicken manure in ratio of 1:1 was applied to container of 100×20×15 cm3.  Fertilization was carried out 2 times daily at the dose of chicken manure 130, 160 and 190 g/container.  The result of study showed that density of bacteria tends to decrease during experiment.  Highest density (11,948 individuals/m2 and biomass (14.65 g/ m2 of bacteria was obtained by 190 g of chicken manure fertilization. Keywords: blood worm, Limnodrilus sp., bacteria, chicken manure, fermentation   ABSTRAK Budidaya cacing Limnodrilus sp., kini sedang dikembangkan untuk menyediakan cacing secara terkontrol dan kontinyu. Media hidup cacing terdiri dari lumpur dan limbah organik. Untuk menjaga persediaan makanan dalam media pemeliharaan, dilakukan pemupukan secara berkala. Salah satu pupuk organik yang digunakan dalam budidaya cacing adalah kotoran ayam karena mengandung unsur N yang lebih tinggi, mudah didapat dan murah. Tujuan penelitian ini adalah untuk mengetahui kelimpahan bakteri pada substrat media budidaya cacing yang dipupuk dengan kotoran ayam hasil fermentasi serta pengaruhnya terhadap pertumbuhan cacing. Substrat yang digunakan berupa lumpur dan kotoran ayam dengan perbandingan 1:1 dan ditempatkan dalam wadah berukuran dimensi 100×20×15 cm3. Pemupukan setiap dua hari menggunakan kotoran ayam hasil fermentasi dengan dosis 130, 160 dan 190 g/wadah menghasilkan perkembangan kelimpahan bakteri yang cenderung menurun selama masa pemeliharaan

  18. Lignocellulose fermentation and residual solids characterization for senescent switchgrass fermentation by Clostridium thermocellum in the presence and absence of continuous in situ ball-milling

    Energy Technology Data Exchange (ETDEWEB)

    Balch, Michael L.; Holwerda, Evert K.; Davis, Mark F.; Sykes, Robert W.; Happs, Renee M.; Kumar, Rajeev; Wyman, Charles E.; Lynd, Lee R.

    2017-04-12

    Milling during lignocellulosic fermentation, henceforth referred to as cotreatment, is investigated as an alternative to thermochemical pretreatment as a means of enhancing biological solubilization of lignocellulose. We investigate the impact of milling on soluble substrate fermentation by Clostridium thermocellum with comparison to yeast, document solubilization for fermentation of senescent switchgrass with and without ball milling, and characterize residual solids. Soluble substrate fermentation by C. thermocellum proceeded readily in the presence of continuous ball milling but was completely arrested for yeast. Total fractional carbohydrate solubilization achieved after fermentation of senescent switchgrass by C. thermocellum for 5 days was 0.45 without cotreatment or pretreatment, 0.81 with hydrothermal pretreatment (200 degrees C, 15 minutes, severity 4.2), and 0.88 with cotreatment. Acetate and ethanol were the main fermentation products, and were produced at similar ratios with and without cotreatment. Analysis of solid residues was undertaken using molecular beam mass spectrometry (PyMBMS) and solid-state nuclear magnetic resonance spectroscopy (NMR) in order to provide insight into changes in plant cell walls during processing via various modes. The structure of lignin present in residual solids remaining after fermentation with cotreatment appeared to change little, with substantially greater changes observed for hydrothermal pretreatment - particularly with respect to formation of C-C bonds. The observation of high solubilization with little apparent modification of the residue is consistent with cotreatment enhancing solubilization primarily by increasing the access of saccharolytic enzymes to the feedstock, and C. thermocellum being able to attack all the major linkages in cellulosic biomass provided that these linkages are accessible.

  19. Change in enzyme production by gradually drying culture substrate during solid-state fermentation.

    Science.gov (United States)

    Ito, Kazunari; Gomi, Katsuya; Kariyama, Masahiro; Miyake, Tsuyoshi

    2015-06-01

    The influence of drying the culture substrate during solid-state fermentation on enzyme production was investigated using a non-airflow box. The drying caused a significant increase in enzyme production, while the mycelium content decreased slightly. This suggests that changes in the water content in the substrate during culture affect enzyme production in fungi. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  20. Boosting dark fermentation with co-cultures of extreme thermophiles for biohythane production from garden waste.

    Science.gov (United States)

    Abreu, Angela A; Tavares, Fábio; Alves, Maria Madalena; Pereira, Maria Alcina

    2016-11-01

    Proof of principle of biohythane and potential energy production from garden waste (GW) is demonstrated in this study in a two-step process coupling dark fermentation and anaerobic digestion. The synergistic effect of using co-cultures of extreme thermophiles to intensify biohydrogen dark fermentation is demonstrated using xylose, cellobiose and GW. Co-culture of Caldicellulosiruptor saccharolyticus and Thermotoga maritima showed higher hydrogen production yields from xylose (2.7±0.1molmol(-1) total sugar) and cellobiose (4.8±0.3molmol(-1) total sugar) compared to individual cultures. Co-culture of extreme thermophiles C. saccharolyticus and Caldicellulosiruptor bescii increased synergistically the hydrogen production yield from GW (98.3±6.9Lkg(-1) (VS)) compared to individual cultures and co-culture of T. maritima and C. saccharolyticus. The biochemical methane potential of the fermentation end-products was 322±10Lkg(-1) (CODt). Biohythane, a biogas enriched with 15% hydrogen could be obtained from GW, yielding a potential energy generation of 22.2MJkg(-1) (VS). Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Lactic acid production from submerged fermentation of broken rice using undefined mixed culture.

    Science.gov (United States)

    Nunes, Luiza Varela; de Barros Correa, Fabiane Fernanda; de Oliva Neto, Pedro; Mayer, Cassia Roberta Malacrida; Escaramboni, Bruna; Campioni, Tania Sila; de Barros, Natan Roberto; Herculano, Rondinelli Donizetti; Fernández Núñez, Eutimio Gustavo

    2017-04-01

    The present work aimed to characterize and optimize the submerged fermentation of broken rice for lactic acid (LA) production using undefined mixed culture from dewatered activated sludge. A microorganism with amylolytic activity, which also produces LA, Lactobacillus amylovorus, was used as a control to assess the extent of mixed culture on LA yield. Three level full factorial designs were performed to optimize and define the influence of fermentation temperature (20-50 °C), gelatinization time (30-60 min) and broken rice concentration in culture medium (40-80 g L-1) on LA production in pure and undefined mixed culture. LA production in mixed culture (9.76 g L-1) increased in sixfold respect to pure culture in optimal assessed experimental conditions. The optimal conditions for maximizing LA yield in mixed culture bioprocess were 31 °C temperature, 45 min gelatinization time and 79 g L-1 broken rice concentration in culture medium. This study demonstrated the positive effect of undefined mixed culture from dewatered activated sludge to produce LA from culture medium formulated with broken rice. In addition, this work establishes the basis for an efficient and low-cost bioprocess to manufacture LA from this booming agro-industrial by-product.

  2. Continuous liquid fermentation of pretreated waste activated sludge for high rate volatile fatty acids production and online nutrients recovery.

    Science.gov (United States)

    Zhang, Lihui; Liu, He; Zheng, Zhiyong; Ma, Huijun; Yang, Meng; Liu, Hongbo

    2017-11-04

    Raw sludge was pretreated, and the separated sludge liquid was used as substrate in a continuous operated up-flow anaerobic sludge blanket reactor to produce volatile fatty acids (VFAs). The highest VFA productivity of continuous fermentation with sludge liquid at an organic loading rate (OLR) of 10.0 kg COD/m3/d was about 5.0-fold and 4.0-fold higher than batch and semi-continuous fermentation with pretreated sludge slurry, respectively. Moreover, the liquid fermentation with an OLR of 10.0 kg COD/m3/d consumed the least energy, which was about 10.57% and 12.12% of batch and semi-continuous sludge fermentation, respectively. When combined with online nitrogen and phosphorus recovery, VFA production further increased by 20.67% and struvite recovery efficiency reached 1.98  ±  0.28 g/g PO43-. The process showed high VFA production, low energy consumption and good nutrients recovery by continuous liquid anaerobic fermentation, significantly increasing the economic potential of VFA production from waste activated sludge. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Comparison of different mixed cultures for bio-hydrogen production from ground wheat starch by combined dark and light fermentation.

    Science.gov (United States)

    Ozmihci, Serpil; Kargi, Fikret

    2010-04-01

    Composition of the mixed culture was varied in combined dark-light fermentation of wheat powder starch in order to improve hydrogen gas formation rate and yield. Heat-treated anaerobic sludge and pure culture of Clostridium beijerinckii (DSMZ 791T) were combined with two different light fermentation bacteria of Rhodobacter sphaeroides (RS-NRRL and RS-RV) in order to select a more suitable mixture resulting in high hydrogen yield and formation rate. A combination of the anaerobic sludge and RS-NRRL yielded the highest cumulative hydrogen (CHF = 140 ml), the highest yield (0.36 mol H2 mol(-1) glucose) and specific hydrogen formation rate (2.5 ml H2 g(-1) biomass h(-1)). During dark fermentation (70 h) hydrogen was produced simultaneously by the dark and light fermentation bacteria using glucose from hydrolyzed starch. However, only light fermentation bacteria produced hydrogen from VFA's derived from dark fermentation after a long adaptation period.

  4. Restorative culture in school. Continuation of discussion

    Directory of Open Access Journals (Sweden)

    A.A. Pentin

    2014-08-01

    Full Text Available The article deals with the lack of effective ways of building relationships, parenting responsibility and conflict solving in the school community. It is addressed to the whole school community – to the administration, psychologists and social workers, to the faculty, parents and students. We discuss the key concepts and principles of “restorative culture” and the reasons for its introduction in educational institutions. The restorative culture refers to activities on formation and spread of interpersonal relations value in the aspect of its understanding, trust, acceptance of active responsibility, separation of problems and subjects, and focus on the successful experience. We briefly discuss the theory of restorative justice and narrative practice. Particular attention is paid to the typical methods of school response to conflicts, and to zero-tolerance policy. We propose that the school community needs a number of specific technologies that would optimally suit for different types of situations and would constitute a part of the system

  5. Selection of functional lactic acid bacteria as starter cultures for the fermentation of Korean leek (Allium tuberosum Rottler ex Sprengel.).

    Science.gov (United States)

    Yang, Jaesik; Ji, Yosep; Park, Hyunjoon; Lee, Jieun; Park, Soyoung; Yeo, Soyoung; Shin, Hyunkil; Holzapfel, Wilhelm H

    2014-11-17

    The purpose of this research was to find safe and suitable starter cultures for the fermentation of Korean leek (Allium tuberosum Rottler), also known as garlic chives or Oriental garlic. This traditional herb has several functional properties and a strong flavour; its leaves are used as food material. Eighteen strains of lactic acid bacteria (LAB) were isolated from well-fermented leek kimchi. Controlled fermentation of the leek leaves was conducted with 2 strains (Weissella confusa LK4 and Lactobacillus plantarum LK8), selected as potential starter cultures on the basis of their safety properties, and on the pH, total titratable acidity (TTA), and viable cell numbers [colony forming units (CFUml(-1))] achieved during the fermentation. Microbial dynamics was also followed during fermentation by using PCR-DGGE (Denaturing Gradient Gel Electrophoresis) on DNA level. To analyse bioactive compounds such as thiols and allicin (diallyl thiosulfinates), the total flavonoid and polyphenolic contents were determined by colorimetric methods. Functional properties were assessed on the basis of anti-oxidative capacities by determining the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging effect, and ferric reducing antioxidant power (FRAP). W. confusa LK4 rapidly increased during the first stage of leek fermentation, and was mainly responsible for accelerated fermentation during the early period in contrast to L. plantarum LK8, a stronger acid producer during the later stages of fermentation. After 48 h fermentation, leeks fermented with W. confusa LK4 showed the highest radical scavenging effects and reducing ability. The detectable amount of allicin of fermented leeks decreased relative to the change in pH, whereas the concentration of thiols significantly increased. Total flavonoid and poly-phenolic contents changed during fermentation and showed correlation with anti-oxidant effects. We therefore suggest the suitability of W. confusa LK4 as a potential starter

  6. Effect of Single Bacterial Starter Culture on Odour Reduction During Controlled Fermentation of Cassava Tubers for Foofoo Production

    OpenAIRE

    Henshaw, E. E.; Ikpoh, I. S

    2010-01-01

    Effects of single bacterial starter culture on odour reduction during controlled fermentation of cassava tubers for foofoo production were investigated. Pure cultures were used to ferment cassava tubers in water for 96 h. The cultures used include Bacillus subtilis, Klebsiela sp., Lactobacillus plantarum and Leuconostoc mesenteroides. L. plantarum exhibited the highest acid producing ability, decreasing the pH of the Cassava tubers from 6.2 to 3.68 with a corresponding increase in total titra...

  7. Cellulosic ethanol fermentation using Saccharomyces cerevisiae seeds cultured by pretreated corn stover material.

    Science.gov (United States)

    Qureshi, Abdul Sattar; Zhang, Jian; Bao, Jie

    2015-03-01

    Utilization of lignocellulose materials to replace the pure glucose for preparation of the fermenting yeast seeds could reduce the cost of ethanol fermentation, because a large quantity of glucose is saved in the large-scale seed fermentor series. In this study, Saccharomyces cerevisiae DQ1 was cultured using the freshly pretreated corn stover material as the carbon source, and then the culture broth was used as the inoculation seeds after a series of seed transfer and inoculated into the ethanol production fermentor. The results show that the yeast cell growth and ethanol fermentation performance have essentially no difference when the yeast seeds were cultured by glucose, the corn stover hydrolysate liquid, and the pretreated corn stover solids as carbon sources, respectively. Approximately 22% of the yeast cell culture cost was saved, and the process flow sheet in industrial scale plants was simplified by using the pretreated corn stover for seed culture. The results provided a practical method for materials and operational cost reduction for cellulosic ethanol production.

  8. Parameter oscillation attenuation and mechanism exploration for continuous VHG ethanol fermentation.

    Science.gov (United States)

    Bai, F W; Ge, X M; Anderson, W A; Moo-Young, M

    2009-01-01

    A bioreactor system composed of a stirred tank and three tubular bioreactors in series was established, and continuous ethanol fermentation was carried out using a general Saccharomyces cerevisiae strain and a very high gravity medium containing 280 g L(-1) glucose, supplemented with 5 g L(-1) yeast extract and 3 g L(-1) peptone. Sustainable oscillations of glucose, ethanol, and biomass were observed when the tank was operated at the dilution rate of 0.027 h(-1), which significantly affected ethanol fermentation performance of the system. After the tubular bioreactors were packed with 1/2'' Intalox ceramic saddles, the oscillations were attenuated and quasi-steady states were achieved. Residence time distributions were studied for the packed bioreactors by the step input response technique using xylose as a tracer, which was added into the medium at a concentration of 20 g L(-1), indicating that the backmixing alleviation assumed for the packed tubular bioreactors could not be established, and its contribution to the oscillation attenuation could not be verified. Furthermore, the role of the packing's yeast cell immobilization in the oscillation attenuation was investigated by packing the tubular bioreactors with packings with significant difference in yeast cell immobilization effects, and the experimental results revealed that only the Intalox ceramic saddles and wood chips with moderate yeast cell immobilization effects could attenuate the oscillations, and correspondingly, improved the ethanol fermentation performance of the system, while the porous polyurethane particles with good yeast cell immobilization effect could not. And the viability analysis for the immobilized yeast cells illustrated that the extremely lower yeast cell viability within the tubular bioreactors packed with the porous polyurethane particles could be the reason for their inefficiency, while the yeast cells loosely immobilized onto the surfaces of the Intalox ceramic saddles and wood

  9. Fermentation profile of Saccharomyces cerevisiae and Candida tropicalis as starter cultures on barley malt medium.

    Science.gov (United States)

    Alloue-Boraud, Wazé Aimée Mireille; N'Guessan, Kouadio Florent; Djeni, N'Dédé Théodore; Hiligsmann, Serge; Djè, Koffi Marcellin; Delvigne, Franck

    2015-08-01

    Saccharomyces cerevisiae C8-5 and Candida tropicalis F0-5 isolated from traditional sorghum beer were tested for kinetic parameters on barley malt extract, YPD (863 medium) and for alcohol production. The results showed that C. tropicalis has the highest maximum growth rate and the lowest doubling time. Values were 0.22 and 0.32 h(-1) for maximum growth rate, 3 h 09 min and 2 h 09 min for doubling time respectively on barley malt extract and YPD. On contrary, glucose consumption was the fastest with S. cerevisiae (-0.36 and -0.722 g/l/h respectively on barley malt extract and YPD). When these two yeasts were used as starters in pure culture and co-culture at proportion of 1:1 and 2:1 (cell/cell) for barley malt extract fermentation, we noticed that maltose content increased first from 12.12 g/l to 13.62-16.46 g/l and then decreased. The highest increase was obtained with starter C. tropicalis + S. cerevisiae 2:1. On contrary, glucose content decreased throughout all the fermentation process. For all the starters used, the major part of the ethanol was produced at 16 h of fermentation. Values obtained in the final beers were 11.4, 11.6, 10.4 and 10.9 g/l for fermentation conducted with S. cerevisiae, C. tropicalis, C. tropicalis + S. cerevisiae 1:1 and C. tropicalis + S. cerevisiae 2:1. Cell viability measurement during the fermentation by using flow cytometry revealed that the lowest mean channel fluorescence for FL3 (yeast rate of death) was obtained with C. tropicalis + S. cerevisiae 2:1 after 48 h of fermentation.

  10. Feeding Aspergillus oryzae Fermentation Culture (AOFC to Growing Sheep: 1. The Effect of AOFC on Rumen Fermentation

    Directory of Open Access Journals (Sweden)

    Darwinsyah Lubis

    2002-10-01

    Full Text Available Cultures of fungi, especially Aspergillus oryzae, have been of interest to animal nutritionists to increase feed efficiency. Many experiments have been done and showed positive results on rumen fermentation and productivity of ruminants. This paper reports the results of an in vivo study on feeding Aspergillus oryzae, fermentation culture (AOFC to growing sheep. ‘Onggok’ (tapioca processing waste was used as media for AO cultivation after being enriched with a mineral mixture. Commercial concentrate (GT-03 was fed to 15 growing sheep supplemented with 0% (C0, 5% (C1, and 10% (C2 AOFC (w/w. Chopped fresh King grass was used as a basal diet. The 3 treatments were randomly allotted to the sheep according to randomized block design with 5 replications. The study was carried out for 14 weeks. Digestion trial was conducted in the last 10 days of experiment. All feed and fecal samples were analyzed for nutrients. Rumen fluid was sampled at the mid experimental period. Analyses were done on rumen pH, ammonia content, (VFA volatile fatly acids concentration, and also total digestive tract digestibility of dry and organic matter, crude protein, and total fiber (NDF. Differences in treatment means were analyzed by Duncan’s MRT. Feeding AOFC resulted in increased (P<0.05 digestibility of crude protein from 59.6% in control sheep to 65.5% in sheep fed concentrate with 10% AOFC supplementation. The same pattern also occurred for NDF, but no effect was found on dry and organic matter. Higher fiber digestibility with AOFC supplementation was in line with an increase (P<0.05 in cellulolytic bacteria population in the rumen. VFA produced also increased (P<0.05, as well as individual acids content, primarily acetate and propionate. No differences (P<0.05 were detected in rumen pH and ammonia content. It appears that AOFC is more suitable for the purpose of meat production.

  11. Comparison of fermentation profiles between lupine and soybean by Aspergillus oryzae and Aspergillus sojae in solid-state culture systems

    NARCIS (Netherlands)

    Sardjono; Zhu, Y.; Knol, W.

    1998-01-01

    To explore the possibilities of using lupine as a soybean replacement in fermented foods, fermentation profiles of lupine and soybean by Aspergillus oryzae and A. sojae, respectively, in a solid-state culture were compared. Biomass, spore concentration, oxygen consumption rate, carbon dioxide

  12. Performance of continuous stirred tank reactor (CSTR) on fermentative biohydrogen production from melon waste

    Science.gov (United States)

    Cahyari, K.; Sarto; Syamsiah, S.; Prasetya, A.

    2016-11-01

    This research was meant to investigate performance of continuous stirred tank reactor (CSTR) as bioreactor for producing biohydrogen from melon waste through dark fermentation method. Melon waste are commonly generated from agricultural processing stages i.e. cultivation, post-harvesting, industrial processing, and transportation. It accounted for more than 50% of total harvested fruit. Feedstock of melon waste was fed regularly to CSTR according to organic loading rate at value 1.2 - 3.6 g VS/ (l.d). Optimum condition was achieved at OLR 2.4 g VS/ (l.d) with the highest total gas volume 196 ml STP. Implication of higher OLR value is reduction of total gas volume due to accumulation of acids (pH 4.0), and lower substrate volatile solid removal. In summary, application of this method might valorize melon waste and generates renewable energy sources.

  13. Global behavior analysis for stochastic system of 1,3-PD continuous fermentation

    Science.gov (United States)

    Zhu, Xi; Kliemann, Wolfgang; Li, Chunfa; Feng, Enmin; Xiu, Zhilong

    2017-12-01

    Global behavior for stochastic system of continuous fermentation in glycerol bio-dissimilation to 1,3-propanediol by Klebsiella pneumoniae is analyzed in this paper. This bioprocess cannot avoid the stochastic perturbation caused by internal and external disturbance which reflect on the growth rate. These negative factors can limit and degrade the achievable performance of controlled systems. Based on multiplicity phenomena, the equilibriums and bifurcations of the deterministic system are analyzed. Then, a stochastic model is presented by a bounded Markov diffusion process. In order to analyze the global behavior, we compute the control sets for the associated control system. The probability distributions of relative supports are also computed. The simulation results indicate that how the disturbed biosystem tend to stationary behavior globally.

  14. Lactic acid bacteria as protective cultures in fermented pork meat to prevent Clostridium spp. growth.

    Science.gov (United States)

    Di Gioia, Diana; Mazzola, Giuseppe; Nikodinoska, Ivana; Aloisio, Irene; Langerholc, Tomaz; Rossi, Maddalena; Raimondi, Stefano; Melero, Beatriz; Rovira, Jordi

    2016-10-17

    In meat fermented foods, Clostridium spp. growth is kept under control by the addition of nitrite. The growing request of consumers for safer products has led to consider alternative bio-based approaches, the use of protective cultures being one of them. This work is aimed at checking the possibility of using two Lactobacillus spp. strains as protective cultures against Clostridium spp. in pork ground meat for fermented salami preparation. Both Lactobacillus strains displayed anti-clostridia activity in vitro using the spot agar test and after co-culturing them in liquid medium with each Clostridium strain. Only one of them, however, namely L. plantarum PCS20, was capable of effectively surviving in ground meat and of performing anti-microbial activity in carnis in a challenge test where meat was inoculated with the Clostridium strain. Therefore, this work pointed out that protective cultures can be a feasible approach for nitrite reduction in fermented meat products. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Effects of Leuconostoc mesenteroides starter cultures on microbial communities and metabolites during kimchi fermentation.

    Science.gov (United States)

    Jung, Ji Young; Lee, Se Hee; Lee, Hyo Jung; Seo, Hye-Young; Park, Wan-Soo; Jeon, Che Ok

    2012-02-15

    Kimchi fermentation usually relies upon the growth of naturally-occurring various heterofermentative lactic acid bacteria (LAB). This sometimes makes it difficult to produce kimchi with uniform quality. The use of Leuconostoc mesenteroides as a starter has been considered to produce commercial fermented kimchi with uniform and good quality in Korea. In this study, a combination of a barcoded pyrosequencing strategy and a (1)H NMR technique was used to investigate the effects of Leu. mesenteroides strain B1 as a starter culture for kimchi fermentation. Baechu (Chinese cabbage) and Chonggak (radish) kimchi with and without Leu. mesenteroides inoculation were prepared, respectively and their characteristics that included pH, cell number, bacterial community, and metabolites were monitored periodically for 40 days. Barcoded pyrosequencing analysis showed that the numbers of bacterial operational taxonomic units (OTU) in starter kimchi decreased more quickly than that in non-starter kimchi. Members of the genera Leuconostoc, Lactobacillus, and Weissella were dominant LAB regardless of the kimchi type or starter inoculation. Among the three genera, Leuconostoc was the most abundant, followed by Lactobacillus and Weissella. The use of Leu. mesenteroides as a starter increased the Leuconostoc proportions and decreased the Lactobacillus proportions in both type of kimchi during kimchi fermentation. However, interestingly, the use of the kimchi starter more highly maintained the Weissella proportions of starter kimchi compared to that in the non-starter kimchi until fermentation was complete. Metabolite analysis using the (1)H NMR technique showed that both Baechu and Chonggak kimchi with the starter culture began to consume free sugars earlier and produced a little greater amounts of lactic and acetic acids and mannitol. Metabolite analysis demonstrated that kimchi fermentation using Leu. mesenteroides as a starter was completed earlier with more production of kimchi

  16. Culture-independent study of the diversity of microbial populations in brines during fermentation of naturally-fermented Aloreña green table olives.

    Science.gov (United States)

    Abriouel, Hikmate; Benomar, Nabil; Lucas, Rosario; Gálvez, Antonio

    2011-01-05

    Aloreña table olives are naturally fermented traditional green olives with a denomination of protection (DOP). The present study focused on Aloreña table olives manufactured by small and medium enterprises (SMEs) from Valle del Guadalhorce (Southern Spain) under three different conditions (cold storage, and ambient temperature fermentations in small vats and in large fermentation tanks). The microbial load of brines during fermentation was studied by plate counting, and the microbial diversity was determined by a culture-independent approach based on PCR-DGGE analysis. The viable microbial populations (total mesophilic counts, yeasts and molds, and lactic acid bacteria - LAB) changed in cell numbers during the course of fermentation. Great differences were also observed between cold, vat and tank fermentations and also from one SME to another. Yeasts seemed to be the predominant populations in cold-fermented olives, while LAB counts increased towards the end of vat and tank fermentations at ambient temperature. According to PCR-DGGE analysis, microbial populations in cold-fermented olives were composed mostly by Gordonia sp./Pseudomonas sp. and Sphingomonas sp./Sphingobium sp./Sphingopyxis sp. together with halophilic archaea (mainly by haloarchaeon/Halosarcina pallida and uncultured archaeon/uncultured haloarchaeon/Halorubrum orientalis) and yeasts (Saccharomyces cerevisiae and Candida cf. apicola). Vat-fermented olives stored at ambient temperature included a more diverse bacterial population: Gordonia sp./Pseudomonas sp., Sphingomonas sp./Sphingobium sp./Sphingopyxis sp. and Thalassomonas agarivorans together with halophilic archaea and yeasts (mainly S. cerevisiae and C. cf. apicola, but also Pichia sp., and Pichia manshurica/Pichia galeiformis). Some LAB were detected towards the end of vat fermentations, including Lactobacillus pentosus/Lactobacillus plantarum and Lactobacillus vaccinostercus/Lactobacillus suebicus. Only the tank fermentation showed a clear

  17. Dark fermentative hydrogen production by defined mixed microbial cultures immobilized on ligno-cellulosic waste materials

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Sanjay K.S. [Microbial Biotechnology and Genomics, Institute of Genomics and Integrative Biology (IGIB), CSIR, Delhi University Campus, Mall Road, Delhi 110007 (India); Department of Biotechnology, University of Pune, Pune 411007 (India); Purohit, Hemant J. [Environmental Genomics Unit, National Environmental Engineering Research Institute (NEERI), CSIR, Nehru Marg, Nagpur 440020 (India); Kalia, Vipin C. [Microbial Biotechnology and Genomics, Institute of Genomics and Integrative Biology (IGIB), CSIR, Delhi University Campus, Mall Road, Delhi 110007 (India)

    2010-10-15

    Mixed microbial cultures (MMCs) based on 11 isolates belonging to Bacillus spp. (Firmicutes), Bordetella avium, Enterobacter aerogenes and Proteus mirabilis (Proteobacteria) were employed to produce hydrogen (H{sub 2}) under dark fermentative conditions. Under daily fed culture conditions (hydraulic retention time of 2 days), MMC6 and MMC4, immobilized on ligno-cellulosic wastes - banana leaves and coconut coir evolved 300-330 mL H{sub 2}/day. Here, H{sub 2} constituted 58-62% of the total biogas evolved. It amounted to a H{sub 2} yield of 1.54-1.65 mol/mol glucose utilized over a period of 60 days of fermentation. The involvement of various Bacillus spp. -Bacillus sp., Bacillus cereus, Bacillus megaterium, Bacillus pumilus and Bacillus thuringiensis as components of the defined MMCs for H{sub 2} production has been reported here for the first time. (author)

  18. A Two-Stage Continuous Fermentation System for Conversion of Syngas into Ethanol

    Directory of Open Access Journals (Sweden)

    Hanno Richter

    2013-08-01

    Full Text Available We have established a two-stage continuous fermentation process for production of ethanol from synthesis gas (syngas with Clostridium ljungdahlii. The system consists of a 1-L continuously stirred tank reactor as a growth stage and a 4-L bubble column equipped with a cell recycle module as an ethanol production stage. Operating conditions in both stages were optimized for the respective purpose (growth in stage one and alcohol formation in stage two. The system was fed with an artificial syngas mixture, mimicking the composition of syngas derived from lignocellulosic biomass (60% CO, 35% H2, and 5% CO2. Gas recycling was used to increase the contact area and retention time of gas in the liquid phase, improving mass transfer and metabolic rates. In stage two, the biocatalyst was maintained at high cell densities of up to 10 g DW/L. Ethanol was continuously produced at concentrations of up to 450 mM (2.1% and ethanol production rates of up to 0.37 g/(L·h. Foam control was essential to maintain reactor stability. A stoichiometric evaluation of the optimized process revealed that the recovery of carbon and hydrogen from the provided carbon monoxide and hydrogen in the produced ethanol was 28% and 74%, respectively.

  19. Profile of volatile compounds during papaya juice fermentation by a mixed culture of Saccharomyces cerevisiae and Williopsis saturnus.

    Science.gov (United States)

    Lee, P-R; Ong, Y-L; Yu, B; Curran, P; Liu, S-Q

    2010-10-01

    This study investigated the formation and utilization of volatile compounds during papaya juice fermentation by a mixed culture of Saccharomyces cerevisiae and Williopsis saturnus. Time-course papaya juice fermentations were carried out using pure cultures of S. cerevisiae var. bayanus R2 and W. saturnus var. mrakii NCYC2251 and a mixed culture of the two yeasts at a ratio of 1:1000 (R2:NCYC2251). Changes in S. cerevisiae cell population, Brix, sugar consumption and pH were similar in the mixed culture and in the S. cerevisiae monoculture. There was an early growth arrest of W. saturnus in the mixed culture fermentation. A range of volatile compounds were produced during fermentation including fatty acids, alcohols, aldehydes and esters and some volatile compounds including those initially present in the juice were utilized. The mixed culture fermentation of S. cerevisiae and W. saturnus benefited from the presence of both yeasts, with more esters being produced than the S. cerevisiae monoculture and more alcohols being formed than the W. saturnus monoculture. The study suggests that papaya juice fermentation with a mixed culture of S. cerevisiae and W. saturnus may be able to result in the formation of more complex aroma compounds and higher ethanol level than those using single yeasts. 2010 Elsevier Ltd. All rights reserved.

  20. A modified indirect mathematical model for evaluation of ethanol production efficiency in industrial-scale continuous fermentation processes.

    Science.gov (United States)

    Canseco Grellet, M A; Castagnaro, A; Dantur, K I; De Boeck, G; Ahmed, P M; Cárdenas, G J; Welin, B; Ruiz, R M

    2016-10-01

    To calculate fermentation efficiency in a continuous ethanol production process, we aimed to develop a robust mathematical method based on the analysis of metabolic by-product formation. This method is in contrast to the traditional way of calculating ethanol fermentation efficiency, where the ratio between the ethanol produced and the sugar consumed is expressed as a percentage of the theoretical conversion yield. Comparison between the two methods, at industrial scale and in sensitivity studies, showed that the indirect method was more robust and gave slightly higher fermentation efficiency values, although fermentation efficiency of the industrial process was found to be low (~75%). The traditional calculation method is simpler than the indirect method as it only requires a few chemical determinations in samples collected. However, a minor error in any measured parameter will have an important impact on the calculated efficiency. In contrast, the indirect method of calculation requires a greater number of determinations but is much more robust since an error in any parameter will only have a minor effect on the fermentation efficiency value. The application of the indirect calculation methodology in order to evaluate the real situation of the process and to reach an optimum fermentation yield for an industrial-scale ethanol production is recommended. Once a high fermentation yield has been reached the traditional method should be used to maintain the control of the process. Upon detection of lower yields in an optimized process the indirect method should be employed as it permits a more accurate diagnosis of causes of yield losses in order to correct the problem rapidly. The low fermentation efficiency obtained in this study shows an urgent need for industrial process optimization where the indirect calculation methodology will be an important tool to determine process losses. © 2016 The Society for Applied Microbiology.

  1. Stable acetate production in extreme-thermophilic (70ºC) mixed culture fermentation by selective enrichment of hydrogenotrophic methanogens

    NARCIS (Netherlands)

    Zhang, F.; Zhang, Y.; Ding, J.; Dai, K.; Van Loosdrecht, M.C.M.; Zeng, R.J.

    2014-01-01

    The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to hydrogen inhibition. In this work, hydrogenotrophic methanogens were selectively enriched to reduce the hydrogen partial pressure and to realize efficient acetate production in

  2. Use of chemostat cultures mimicking different phases of wine fermentations as a tool for quantitative physiological analysis

    National Research Council Canada - National Science Library

    Vázquez-Lima, Felícitas; Silva, Paulina; Barreiro, Antonio; Martínez-Moreno, Rubén; Morales, Pilar; Quirós, Manuel; González, Ramón; Albiol, Joan; Ferrer, Pau

    2014-01-01

    .... In this study, we implemented and validated the use of chemostat cultures as a tool to simulate different stages of a standard wine fermentation, thereby allowing to implement metabolic flux analyses...

  3. Fermentative capabilities and volatile compounds produced by Kloeckera/Hanseniaspora and Saccharomyces yeast strains in pure and mixed cultures during Agave tequilana juice fermentation.

    Science.gov (United States)

    González-Robles, Ivonne Wendolyne; Estarrón-Espinosa, Mirna; Díaz-Montaño, Dulce María

    2015-09-01

    The fermentative and aromatic capabilities of Kloeckera africana/Hanseniaspora vineae K1, K. apiculata/H. uvarum K2, and Saccharomyces cerevisiae S1 and S2 were studied in pure and mixed culture fermentations using Agave tequila juice as the culture medium. In pure and mixed cultures, Kloeckera/Hanseniaspora strains showed limited growth and sugar consumption, as well as low ethanol yield and productivity, compared to S. cerevisiae, which yielded more biomass, ethanol and viable cell concentrations. In pure and mixed cultures, S. cerevisiae presented a similar behaviour reaching high biomass production, completely consuming the sugar, leading to high ethanol production. Furthermore, the presence of S. cerevisiae strains in the mixed cultures promoted the production of higher alcohols, acetaldehyde and ethyl esters, whereas Kloeckera/Hanseniaspora strains stimulated the production of ethyl acetate and 2-phenyl ethyl acetate compounds.

  4. In vitro fermentation studies for selection and evaluation of Bacillus strains as starter cultures for the production of okpehe, a traditional African fermented condiment.

    Science.gov (United States)

    Oguntoyinbo, Folarin A; Sanni, Abiodun I; Franz, Charles M A P; Holzapfel, Wilhelm H

    2007-01-25

    Selected Bacillus and Enterococcus strains, isolated from traditional okpehe fermentations, were studied for their suitability as starter cultures in laboratory-scale fermentations of Prosopis africana seeds for the production of okpehe, a traditional fermented vegetable product of Nigeria. The strains were selected on the basis of highest proteolytic activity, as determined with the APIZYM (BioMerieux) test. The choice of starter strains was narrowed to Bacillus subtilis strains BFE 5301 and BFE 5372. These were determined as the best starter combination because of rapid growth, high amylolytic and proteolytic activities, high levels of polyglutamic acid production by strain BFE 5372, as well as bacteriocin production by strain BFE 5301. Other mixed culture fermentations did not yield sensorically acceptable products. Although a monoculture fermentation, using only B. subtilis strain BFE 5372, produced okpehe with very good sensory characteristics, the growth of B. cereus could be detected after 48 h fermentation, indicating that this starter did not sufficiently contribute to product safety. Mixed culture fermentation with the combination of bacteriocin-producing starter B. subtilis BFE 5301 and the non-bacteriocin-producing B. subtilis BFE 5372, produced a product with good sensory characteristics, in which growth of B. cereus was delayed. The bacteriocin produced by B. subtilis strain BFE 5301 was identified as subtilisin, using subtilisin-specific primers and PCR amplification of the subtilisin gene. The bacteriocin was heat-stable at 100 degrees C for 10 min and exhibited highest activity at pH values lower or equal to pH 6.0. The bacteriocin was sensitive to the proteolytic enzymes trypsin and alpha-chymotrypsin at concentrations of 10 mg/ml.

  5. Reduction of histamine and biogenic amines during salted fish fermentation by Bacillus polymyxa as a starter culture

    Directory of Open Access Journals (Sweden)

    Yi-Chen Lee

    2016-01-01

    Full Text Available Bacillus polymyxa D05-1, isolated from salted fish product and possessing amine degrading activity, was used as a starter culture in salted fish fermentation in this study. Fermentation was held at 35°C for 120 days. The water activity in control samples (without starter culture and inoculated samples (inoculated with B. polymyxa D05-1 remained constant throughout fermentation, whereas the pH value rose slightly during fermentation. Salt contents in both samples were constant in the range of 17.5–17.8% during the first 60 days of fermentation and thereafter increased slowly. The inoculated samples had considerably lower levels of total volatile basic nitrogen (p < 0.05 than control samples at each sampling time during 120 days of fermentation. Aerobic bacterial counts in inoculated samples were retarded during the first 60 days of fermentation and thereafter increased slowly, whereas those of control samples increased rapidly with increased fermentation time. However, the aerobic bacterial counts of control samples were significantly higher (p < 0.05 than those of inoculated samples after 40 days of fermentation. In general, overall biogenic amine contents (including histamine, putrescine, cadaverine, and tyramine in the control samples were markedly higher (p < 0.05 than those of the inoculated samples throughout fermentation. After 120 days of fermentation, the histamine and overall biogenic amine contents in the inoculated samples were reduced by 34.0% and 30.0%, respectively, compared to control samples. These results emphasize that the application of starter culture with amines degrading activity in salted fish products was effective in reducing biogenic amine accumulation.

  6. Direct Succinic Acid Production from Minimally Pretreated Biomass Using Sequential Solid-State and Slurry Fermentation with Mixed Fungal Cultures

    Directory of Open Access Journals (Sweden)

    Jerico Alcantara

    2017-06-01

    Full Text Available Conventional bio-based succinic acid production involves anaerobic bacterial fermentation of pure sugars. This study explored a new route for directly producing succinic acid from minimally-pretreated lignocellulosic biomass via a consolidated bioprocessing technology employing a mixed lignocellulolytic and acidogenic fungal co-culture. The process involved a solid-state pre-fermentation stage followed by a two-phase slurry fermentation stage. During the solid-state pre-fermentation stage, Aspergillus niger and Trichoderma reesei were co-cultured in a nitrogen-rich substrate (e.g., soybean hull to induce cellulolytic enzyme activity. The ligninolytic fungus Phanerochaete chrysosporium was grown separately on carbon-rich birch wood chips to induce ligninolytic enzymes, rendering the biomass more susceptible to cellulase attack. The solid-state pre-cultures were then combined in a slurry fermentation culture to achieve simultaneous enzymatic cellulolysis and succinic acid production. This approach generated succinic acid at maximum titers of 32.43 g/L after 72 h of batch slurry fermentation (~10 g/L production, and 61.12 g/L after 36 h of addition of fresh birch wood chips at the onset of the slurry fermentation stage (~26 g/L production. Based on this result, this approach is a promising alternative to current bacterial succinic acid production due to its minimal substrate pretreatment requirements, which could reduce production costs.

  7. Evaluation of Mixed Probiotic Starter Cultures Isolated from Kimchi on Physicochemical and Functional Properties, and Volatile Compounds of Fermented Hams.

    Science.gov (United States)

    Kim, Young Joo; Park, Sung Yong; Lee, Hong Chul; Yoo, Seung Seok; Oh, Sejong; Kim, Kwang Hyun; Chin, Koo Bok

    2016-01-01

    The objective of this study was to investigate the effects of mixed starter cultures isolated from kimchi on physicochemical properties, functionality and flavors of fermented ham. Physicochemical properties, microbial counts, shear force, cholesterol contents and volatile compounds of fermented ham were investigated during processing (curing and ripening time). Curing process for 7 d increased saltiness, however, decreased hunter color values (L, a, and b values). Ripening process for 21 d increased most parameters, such as saltiness, color values, weight loss, shear force and cholesterol content due to the drying process. The mixed starter culture had higher lactic acid bacteria than the commercial one. While eight volatile compounds were identified from fermented hams during curing process, total fiftyeight volatile compounds were identified from fermented hams during ripening process. The main volatile compounds were alcohols, esters and furans. However, no differences in volatile compounds were observed between two batches. Fermented hams (batch B) manufactured with probiotic starter culture (LPP) had higher sensory score in texture, color and overall acceptability than counterparts (batch A), while the opposite trend was observed in flavor. Therefore, mixed probiotic starter culture isolated from kimchi might be used as a starter culture to be able to replace with commercial starter culture (LK-30 plus) for the manufacture of fermented ham.

  8. Evolutionary Engineering in Chemostat Cultures for Improved Maltotriose Fermentation Kinetics in Saccharomyces pastorianus Lager Brewing Yeast.

    Science.gov (United States)

    Brickwedde, Anja; van den Broek, Marcel; Geertman, Jan-Maarten A; Magalhães, Frederico; Kuijpers, Niels G A; Gibson, Brian; Pronk, Jack T; Daran, Jean-Marc G

    2017-01-01

    The lager brewing yeast Saccharomyces pastorianus, an interspecies hybrid of S. eubayanus and S. cerevisiae, ferments maltotriose, maltose, sucrose, glucose and fructose in wort to ethanol and carbon dioxide. Complete and timely conversion ("attenuation") of maltotriose by industrial S. pastorianus strains is a key requirement for process intensification. This study explores a new evolutionary engineering strategy for improving maltotriose fermentation kinetics. Prolonged carbon-limited, anaerobic chemostat cultivation of the reference strain S. pastorianus CBS1483 on a maltotriose-enriched sugar mixture was used to select for spontaneous mutants with improved affinity for maltotriose. Evolved populations exhibited an up to 5-fold lower residual maltotriose concentration and a higher ethanol concentration than the parental strain. Uptake studies with 14C-labeled sugars revealed an up to 4.75-fold higher transport capacity for maltotriose in evolved strains. In laboratory batch cultures on wort, evolved strains showed improved attenuation and higher ethanol concentrations. These improvements were also observed in pilot fermentations at 1,000-L scale with high-gravity wort. Although the evolved strain exhibited multiple chromosomal copy number changes, analysis of beer made from pilot fermentations showed no negative effects on flavor compound profiles. These results demonstrate the potential of evolutionary engineering for strain improvement of hybrid, alloploid brewing strains.

  9. GROWTH CAPACITY OF BACILLUS POTENTIAL STARTER STRAINS ISOLATED FROM COCOA BEANS FERMENTATION UNDER CULTURE STRESS CONDITIONS

    Directory of Open Access Journals (Sweden)

    WILFRIED YAO

    2017-06-01

    Full Text Available The study investigates the growth capacity of Bacillus with pectinolytic activity, acidifying and citrate metabolism capacities under culture stress conditions. Spontaneous heaps fermentation was conducted from cocoa of six producing regions of Côte d’Ivoire. Bacillus isolated using plate agar on nutrient medium were analyzed for pectinolytic enzymes production, citric acid breakdown, acidification and growth capacity under different stress conditions. A total of 970 Bacillus strains were isolated and 44.53 % of them produced pectinolytic activity. Among pectinolytic strains, 163 (37.73 % exhibited acidifying and citrate metabolism capacity. Five (5 of these strains exhibited a strong thermotolerance at 50 ºC with the optimal growth at 35 ºC and a good capacity to grow at pH 4 to pH 8. Moreover, sugar concentrations ranged 5 to 25 % showed low effect on all tested strains growth with a maximum growth at 5 % fructose and sucrose concentration and at 15% glucose concentration. However, ethanol stress conditions (up to 8 % repress strongly growth capacity of the strains analyzed. This study indicates that Bacillus strains involved in Ivorian cocoa fermentation possess some properties essential for a well-fermented cocoa. Therefore, these results show that Bacillus studied should be potential candidate as starter for cocoa beans fermentation control.

  10. Evolutionary Engineering in Chemostat Cultures for Improved Maltotriose Fermentation Kinetics in Saccharomyces pastorianus Lager Brewing Yeast

    Directory of Open Access Journals (Sweden)

    Anja Brickwedde

    2017-09-01

    Full Text Available The lager brewing yeast Saccharomyces pastorianus, an interspecies hybrid of S. eubayanus and S. cerevisiae, ferments maltotriose, maltose, sucrose, glucose and fructose in wort to ethanol and carbon dioxide. Complete and timely conversion (“attenuation” of maltotriose by industrial S. pastorianus strains is a key requirement for process intensification. This study explores a new evolutionary engineering strategy for improving maltotriose fermentation kinetics. Prolonged carbon-limited, anaerobic chemostat cultivation of the reference strain S. pastorianus CBS1483 on a maltotriose-enriched sugar mixture was used to select for spontaneous mutants with improved affinity for maltotriose. Evolved populations exhibited an up to 5-fold lower residual maltotriose concentration and a higher ethanol concentration than the parental strain. Uptake studies with 14C-labeled sugars revealed an up to 4.75-fold higher transport capacity for maltotriose in evolved strains. In laboratory batch cultures on wort, evolved strains showed improved attenuation and higher ethanol concentrations. These improvements were also observed in pilot fermentations at 1,000-L scale with high-gravity wort. Although the evolved strain exhibited multiple chromosomal copy number changes, analysis of beer made from pilot fermentations showed no negative effects on flavor compound profiles. These results demonstrate the potential of evolutionary engineering for strain improvement of hybrid, alloploid brewing strains.

  11. Effects of cultured wild-ginseng root and xylitol on fermentation of kimchi.

    Science.gov (United States)

    Lee, Kun-Jong; Sung, Jung-Min; Kwon, Yong-Suk; Chung, Heajung

    2014-01-01

    This study evaluates the effects of cultured wild ginseng root (0.05%, 0.1% v/w) and xylitol in kimchi. The fermented characteristics of kimchi were investigated during 28 days of fermentation at 4°C. The pH value in the sample with the cultured wild ginseng root was higher than that of control group. The total acidity in the sugar groups (SG groups) was higher than that of xylitol groups (XG groups). Comparing total bacterial count, XG groups were lower than SG groups, regardless of the additional ratio of the cultured wild ginseng root. Reducing sugar of XG groups decreased more slowly than SG groups for seven days; glucose and fructose of XG groups were lower than the control group. DPPH radical scavenging activity was higher in groups with cultured wild ginseng root than in control. In the result of sensory evaluation, XG groups were more preferred than other groups. In conclusion, our results indicate that cultured wild-ginseng root and xylitol have a positive effect on the quality of kimchi, such as antimicrobial and antioxidant functions.

  12. Development of an alternative culture medium for the selective enumeration of Lactobacillus casei in fermented milk.

    Science.gov (United States)

    Colombo, Monique; de Oliveira, Aline Evelyn Zimmermann; de Carvalho, Antonio Fernandes; Nero, Luís Augusto

    2014-05-01

    Monitoring the populations of probiotic strains of the species Lactobacillus casei in food is required by food industries in order to assure that a minimum concentration of these organisms will be ingested by consumers. In this context, Petrifilm™ AC plates can be used along with selective culture media to allow the enumeration of specific groups of lactic acid bacteria. The present study aimed to assess chemical substances as selective agents for Lb. casei in order to propose a selective culture medium to be used with Petrifilm™ AC plates as an alternative protocol for the enumeration of probiotic strains of this species in fermented milk. Twenty-six probiotic and starter cultures (including six strains of Lb. casei) were plated on de Man Rogosa and Sharpe (MRS) agar with distinct concentrations of nalidixic acid, bile, lithium chloride, metronidazole, sodium propionate, and vancomycin. Vancomycin at 10 mg/L demonstrated selective activity for Lb. casei. In addition, 2,3,5-triphenyltetrazolium chlorine was identified as a compound that did not inhibit Lb. casei, and Petrifilm™ AC plates used with MRS and vancomycin at 10 mg/L (MRS-V) demonstrated more colonies of this organism when incubated under anaerobic conditions than aerobic conditions. Acidophilus milk and yoghurt were prepared, added to Lb. casei strains, and stored at 4 °C. Lb. casei populations were monitored using MRS-V and MRTLV by conventional plating and associated with Petrifilm™ AC plates. All correlation indices between counts obtained by conventional plating and Petrifilm™ AC were significant (p casei strains in fermented milk. However, the selective potential of this culture medium must be evaluated considering the specific strains of Lb. casei and the starter cultures inoculated in the fermented milk that requires monitoring. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Metabolic energy-based modelling explains product yielding in anaerobic mixed culture fermentations.

    Directory of Open Access Journals (Sweden)

    Rebeca González-Cabaleiro

    Full Text Available The fermentation of glucose using microbial mixed cultures is of great interest given its potential to convert wastes into valuable products at low cost, however, the difficulties associated with the control of the process still pose important challenges for its industrial implementation. A deeper understanding of the fermentation process involving metabolic and biochemical principles is very necessary to overcome these difficulties. In this work a novel metabolic energy based model is presented that accurately predicts for the first time the experimentally observed changes in product spectrum with pH. The model predicts the observed shift towards formate production at high pH, accompanied with ethanol and acetate production. Acetate (accompanied with a more reduced product and butyrate are predicted main products at low pH. The production of propionate between pH 6 and 8 is also predicted. These results are mechanistically explained for the first time considering the impact that variable proton motive potential and active transport energy costs have in terms of energy harvest over different products yielding. The model results, in line with numerous reported experiments, validate the mechanistic and bioenergetics hypotheses that fermentative mixed cultures products yielding appears to be controlled by the principle of maximum energy harvest and the necessity of balancing the redox equivalents in absence of external electron acceptors.

  14. Metabolic energy-based modelling explains product yielding in anaerobic mixed culture fermentations.

    Science.gov (United States)

    González-Cabaleiro, Rebeca; Lema, Juan M; Rodríguez, Jorge

    2015-01-01

    The fermentation of glucose using microbial mixed cultures is of great interest given its potential to convert wastes into valuable products at low cost, however, the difficulties associated with the control of the process still pose important challenges for its industrial implementation. A deeper understanding of the fermentation process involving metabolic and biochemical principles is very necessary to overcome these difficulties. In this work a novel metabolic energy based model is presented that accurately predicts for the first time the experimentally observed changes in product spectrum with pH. The model predicts the observed shift towards formate production at high pH, accompanied with ethanol and acetate production. Acetate (accompanied with a more reduced product) and butyrate are predicted main products at low pH. The production of propionate between pH 6 and 8 is also predicted. These results are mechanistically explained for the first time considering the impact that variable proton motive potential and active transport energy costs have in terms of energy harvest over different products yielding. The model results, in line with numerous reported experiments, validate the mechanistic and bioenergetics hypotheses that fermentative mixed cultures products yielding appears to be controlled by the principle of maximum energy harvest and the necessity of balancing the redox equivalents in absence of external electron acceptors.

  15. Application of near-infrared spectroscopy for monitoring and control of cell culture and fermentation.

    Science.gov (United States)

    Cervera, Albert E; Petersen, Nanna; Lantz, Anna Eliasson; Larsen, Anders; Gernaey, Krist V

    2009-01-01

    Near-infrared (NIR) spectroscopy can potentially provide on-line information on substrate, biomass, product, and metabolite concentrations in fermentation processes, which could be useful for improved monitoring or control. However, several factors can negatively influence the quality of chemometric models built for interpretation of the spectra, thus impairing the analyte concentration predictions. The aim of this review was to provide an overview of necessary conditions and challenges that one has to face when developing a NIR application for monitoring of cell culture or fermentation processes. Important practical aspects are introduced, such as sampling, modeling of biomass concentration, influence of microorganism morphology on the spectra, effects of the hydrodynamic conditions in the fermenter, temperature influence, instrument settings, and signal optimization. Several examples from the literature are provided, which will hopefully guide the reader interested in the topic. Furthermore, the general procedure used for the development of calibration models is presented, and the influence of microorganism metabolism-potential source of correlation between analytes-is commented. Other important issues such as wavelength selection and evaluation of robustness are shortly introduced. Finally, some examples of potential applications of NIR monitoring are provided, including the implementation of control strategies, the combination with other monitoring tools (the so-called sensor fusion), and the description of process trajectories. On the basis of the review, we conclude that acceptance of NIR spectroscopy as a standard monitoring tool by the fermentation industry will necessitate considerably more on-line studies using industrially relevant-and highly challenging-fermentation conditions (high aeration intensity, high biomass concentration and viscosity, and filamentous production strain). (c) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009.

  16. Effect of time of cutting and maceration on forage composition, nutrient flow, microbial protein synthesis, and digestibility in dual-flow continuous culture

    Science.gov (United States)

    Maceration and evening-cutting are two forage management techniques that have improved forage quality and nutrient utilization in ruminants independently, but have not been evaluated in combination. Using a dual-flow continuous culture fermenter system, this study evaluated the individual and combin...

  17. CO₂ from alcoholic fermentation for continuous cultivation of Arthrospira (Spirulina) platensis in tubular photobioreactor using urea as nitrogen source.

    Science.gov (United States)

    Matsudo, Marcelo C; Bezerra, Raquel P; Converti, Attilio; Sato, Sunao; Carvalho, João Carlos M

    2011-01-01

    Carbon dioxide released from alcoholic fermentation accounts for 33% of the whole CO(2) involved in the use of ethanol as fuel derived from glucose. As Arthrospira platensis can uptake this greenhouse gas, this study evaluates the use of the CO(2) released from alcoholic fermentation for the production of Arthrospira platensis. For this purpose, this cyanobacterium was cultivated in continuous process using urea as nitrogen source, either using CO(2) from alcoholic fermentation, without any treatment, or using pure CO(2) from cylinder. The experiments were carried out at 120 μmol photons m(-2) s(-1) in tubular photobioreactor at different dilution rates (0.2 ≤ D ≤ 0.8 d(-1) ). Using CO(2) from alcoholic fermentation, maximum steady-state cell concentration (2661 ± 71 mg L(-1) ) was achieved at D = 0.2 d(-1) , whereas higher dilution rate (0.6 d(-1) ) was needed to maximize cell productivity (839 mg L(-1) d(-1) ). This value was 10% lower than the one obtained with pure CO(2) , and there was no significant difference in the biomass protein content. With D = 0.8 d(-1) , it was possible to obtain 56% ± 1.5% and 50% ± 1.2% of protein in the dry biomass, using pure CO(2) and CO(2) from alcoholic fermentation, respectively. These results demonstrate that the use of such cost free CO(2) from alcoholic fermentation as carbon source, associated with low cost nitrogen source, may be a promising way to reduce costs of continuous cultivation of photosynthetic microorganisms, contributing at the same time to mitigate the greenhouse effect. Copyright © 2011 American Institute of Chemical Engineers (AIChE).

  18. Competitiveness and antibacterial potential of bacteriocin-producing starter cultures in different types of fermented sausages.

    Science.gov (United States)

    Ravyts, Frédéric; Barbuti, Silvana; Frustoli, Maria Angela; Parolari, Giovanni; Saccani, Giovanna; De Vuyst, Luc; Leroy, Frédéric

    2008-09-01

    Application of bacteriocin-producing starter cultures of lactic acid bacteria in fermented sausage production contributes to food safety. This is sometimes hampered by limited efficacy in situ and by uncertainty about strain dependency and universal applicability for different sausage types. In the present study, a promising antilisterial-bacteriocin producer, Lactobacillus sakei CTC 494, was applied as a coculture in addition to commercial fermentative starters in different types of dry-fermented sausages. The strain was successful in both Belgian-type sausage and Italian salami that were artificially contaminated with about 3.5 log CFU g(-1) of Listeria monocytogenes. After completion of the production process, this led to listerial reductions of up to 1.4 and 0.6 log CFU g(-1), respectively. In a control sausage, containing only the commercial fermentative starter, the reduction was limited to 0.8 log CFU g(-1) for the Belgian-type recipe, where pH decreased from 5.9 to 4.9, whereas an increase of 0.2 log CFU g(-1) was observed for Italian salami, in which the pH rose from 5.7 to 5.9 after an initial decrease to pH 5.3. In a Cacciatore recipe inoculated with 5.5 log CFU g(-1) of L. monocytogenes and in the presence of L. sakei CTC 494, there was a listerial reduction of 1.8 log CFU g(-1) at the end of the production process. This was superior to the effect obtained with the control sausage (0.8 log CFU g(-1)). Two commercial antilisterial cultures yielded reductions of 1.2 and 1.5 log CFU g(-1). Moreover, repetitive DNA sequence-based PCR fingerprinting demonstrated the competitive superiority of L. sakei CTC 494.

  19. Biodegradation of Palm Kernel Cake by Cellulolytic and Hemicellulolytic Bacterial Cultures through Solid State Fermentation

    Directory of Open Access Journals (Sweden)

    Mohamed Idris Alshelmani

    2014-01-01

    Full Text Available Four cellulolytic and hemicellulolytic bacterial cultures were purchased from the Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Culture (DSMZ and the American Type Culture Collection (ATCC. Two experiments were conducted; the objective of the first experiment was to determine the optimum time period required for solid state fermentation (SSF of palm kernel cake (PKC, whereas the objective of the second experiment was to investigate the effect of combinations of these cellulolytic and hemicellulolytic bacteria on the nutritive quality of the PKC. In the first experiment, the SSF was lasted for 12 days with inoculum size of 10% (v/w on different PKC to moisture ratios. In the second experiment, fifteen combinations were created among the four microbes with one untreated PKC as a control. The SSF lasted for 9 days, and the samples were autoclaved, dried, and analyzed for proximate analysis. Results showed that bacterial cultures produced high enzymes activities at the 4th day of SSF, whereas their abilities to produce enzymes tended to be decreased to reach zero at the 8th day of SSF. Findings in the second experiment showed that hemicellulose and cellulose was significantly P<0.05 decreased, whereas the amount of reducing sugars were significantly P<0.05 increased in the fermented PKC (FPKC compared with untreated PKC.

  20. Inoculation of starter cultures in a semi-dry coffee (Coffea arabica) fermentation process.

    Science.gov (United States)

    Evangelista, Suzana Reis; Miguel, Maria Gabriela da Cruz Pedrozo; Cordeiro, Cecília de Souza; Silva, Cristina Ferreira; Pinheiro, Ana Carla Marques; Schwan, Rosane Freitas

    2014-12-01

    The aim of this study was to evaluate the use of yeasts as starter cultures in coffee semi-dry processing. Arabica coffee was inoculated with one of the following starter cultures: Saccharomyces cerevisiae UFLA YCN727, S. cerevisiae UFLA YCN724, Candida parapsilosis UFLA YCN448 and Pichia guilliermondii UFLA YCN731. The control was not inoculated with a starter culture. Denaturing gradient gel electrophoresis (DGGE) was used to assess the microbial population, and organic acids and volatile compounds were quantified by HPLC and HS-SPME/GC, respectively. Sensory analyses were evaluated using the Temporal Dominance of Sensations (TDS). DGGE analysis showed that the inoculated yeasts were present throughout the fermentation. Other yeast species were also detected, including Debaryomyces hansenii, Cystofilobasidium ferigula and Trichosporon cavernicola. The bacterial population was diverse and was composed of the following genera: Weissella, Leuconostoc, Gluconobacter, Pseudomonas, Pantoea, Erwinia and Klebsiella. Butyric and propionic acids, were not detected in any treatment A total of 47 different volatiles compounds have been identified. The coffee inoculated with yeast had a caramel flavor that was not detected in the control, as assessed by TDS. The use of starter cultures during coffee fermentation is an interesting alternative for obtaining a beverage quality with distinctive flavor. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Examination of protein degradation in continuous flow, microbial electrolysis cells treating fermentation wastewater.

    Science.gov (United States)

    Nam, Joo-Youn; Yates, Matthew D; Zaybak, Zehra; Logan, Bruce E

    2014-11-01

    Cellulose fermentation wastewaters (FWWs) contain short chain volatile fatty acids and alcohols, but they also have high concentrations of proteins. Hydrogen gas production from FWW was examined using continuous flow microbial electrolysis cells (MECs), with a focus on fate of the protein. H2 production rates were 0.49±0.05 m(3)/m(3)-d for the FWW, compared to 0.63±0.02 m(3)/m(3)-d using a synthetic wastewater containing only acetate (applied potential of 0.9 V). Total organic matter removal was 76±6% for the FWW, compared to 87±5% for acetate. The MEC effluent became relatively enriched in protein (69%) compared to that in the original FWW (19%). Protein was completely removed using higher applied voltages (1.0 or 1.2 V), but current generation was erratic due to more positive anode potentials (-113±38 mV, Eap=1.2V; -338±38 mV, 1.0 V; -0.426±4 mV, 0.9V). Bacteria on the anodes with FWW were primarily Deltaproteobacteria, while Archaea were predominantly Methanobacterium. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Examination of protein degradation in continuous flow, microbial electrolysis cells treating fermentation wastewater

    KAUST Repository

    Nam, Joo-Youn

    2014-11-01

    © 2014 Elsevier Ltd. Cellulose fermentation wastewaters (FWWs) contain short chain volatile fatty acids and alcohols, but they also have high concentrations of proteins. Hydrogen gas production from FWW was examined using continuous flow microbial electrolysis cells (MECs), with a focus on fate of the protein. H2 production rates were 0.49±0.05m3/m3-d for the FWW, compared to 0.63±0.02m3/m3-d using a synthetic wastewater containing only acetate (applied potential of 0.9V). Total organic matter removal was 76±6% for the FWW, compared to 87±5% for acetate. The MEC effluent became relatively enriched in protein (69%) compared to that in the original FWW (19%). Protein was completely removed using higher applied voltages (1.0 or 1.2V), but current generation was erratic due to more positive anode potentials (-113±38mV, Eap=1.2V; -338±38mV, 1.0V; -0.426±4mV, 0.9V). Bacteria on the anodes with FWW were primarily Deltaproteobacteria, while Archaea were predominantly Methanobacterium.

  3. Bioconversion of Waste Gases into Biofuel via Fermentation in a Continuous Stirred Tank Bioreactor

    Directory of Open Access Journals (Sweden)

    Najafpour, G.

    2005-01-01

    Full Text Available Biological hydrogen production was carried out in a continuous stirred tank bioreactor. A photosynthetic bacterium, Rhodospirillum rubrum, was used as biocatalyst to oxidize carbon monoxides in the waste gas generated from biomass in a gasification process. The fresh liquid media was supplied for microbial growth which contained sodium acetate as carbon source at initial concentration of 4 gL-1. The optimum media space velocity or the suitable ratio of liquid flow rate to the reactor volume (F/VL was 0.02 h-1. At the steady state condition, the concentration of acetate was independent of the dilution rate and it was approximately 1.5 gL-1. The average cell dry weight in the fermentation broth was at satisfactory concentration, approximately 3.4 gL-1 with dilution rate at 0.55 mL min-1. The maximum value of KLa and CO conversion were about 58 h-1 and 80%, respectively, with agitation speed at 500 rpm and gas flow rate at 14 mL min-1. At this condition, the maximum yield of hydrogen production was 0.82 mmol H2•mmol-1 CO.

  4. The Use of Lactic Acid Bacteria Starter Culture in the Production of Nunu, a Spontaneously Fermented Milk Product in Ghana

    Directory of Open Access Journals (Sweden)

    Fortune Akabanda

    2014-01-01

    Full Text Available Nunu, a spontaneously fermented yoghurt-like product, is produced and consumed in parts of West Africa. A total of 373 predominant lactic acid bacteria (LAB previously isolated and identified from Nunu product were assessed in vitro for their technological properties (acidification, exopolysaccharides production, lipolysis, proteolysis and antimicrobial activities. Following the determination of technological properties, Lactobacillus fermentum 22-16, Lactobacillus plantarum 8-2, Lactobacillus helveticus 22-7, and Leuconostoc mesenteroides 14-11 were used as single and combined starter cultures for Nunu fermentation. Starter culture fermented Nunu samples were assessed for amino acids profile and rate of acidification and were subsequently evaluated for consumer acceptability. For acidification properties, 82%, 59%, 34%, and 20% of strains belonging to Lactobacillus helveticus, L. plantarum, L. fermentum, and Leu. mesenteriodes, respectively, demonstrated fast acidification properties. High proteolytic activity (>100 to 150 μg/mL was observed for 50% Leu. mesenteroides, 40% L. fermentum, 41% L. helveticus, 27% L. plantarum, and 10% Ent. faecium species. In starter culture fermented Nunu samples, all amino acids determined were detected in Nunu fermented with single starters of L. plantarum and L. helveticus and combined starter of L. fermntum and L. helveticus. Consumer sensory analysis showed varying degrees of acceptability for Nunu fermented with the different starter cultures.

  5. Continuity and discontinuity in the Inuit culture of Greenland

    NARCIS (Netherlands)

    Kylstra, Hans P.

    1977-01-01

    In november 1976 the Arctic Centre of the University of Gronlngen organized its third symposium. The third symposium was a Dutch-Danish one on the Greenlandic Inuit: 'Continuity and Discontinuity In Greenlandic Arctic Culture'. As on the two previous occasions, an exhibition was organized.

  6. Impact of osmotic stress and ethanol inhibition in yeast cells on process oscillation associated with continuous very-high-gravity ethanol fermentation.

    Science.gov (United States)

    Wang, Liang; Zhao, Xin-Qing; Xue, Chuang; Bai, Feng-Wu

    2013-09-16

    VHG fermentation is a promising process engineering strategy aiming at improving ethanol titer, and thus saving energy consumption for ethanol distillation and distillage treatment. However, sustained process oscillation was observed during continuous VHG ethanol fermentation, which significantly affected ethanol fermentation performance of the system. Sustained process oscillation was investigated in continuous VHG ethanol fermentation, and stresses exerted on yeast cells by osmotic pressure from unfermented sugars and ethanol inhibition developed within the fermentation system were postulated to be major factors triggering this phenomenon. In this article, steady state was established for continuous ethanol fermentation with LG medium containing 120 g/L glucose, and then 160 g/L non-fermentable xylose was supplemented into the LG medium to simulate the osmotic stress on yeast cells under the VHG fermentation condition, but the fermentation process was still at steady state, indicating that the impact of osmotic stress on yeast cells was not the main reason for the process oscillation. However, when 30 g/L ethanol was supplemented into the LG medium to simulate the ethanol inhibition in yeast cells under the VHG fermentation condition, process oscillation was triggered, which was augmented with extended oscillation period and exaggerated oscillation amplitude as ethanol supplementation was increased to 50 g/L, but the process oscillation was gradually attenuated when the ethanol supplementations were stopped, and the steady state was restored. Furthermore, gas stripping was incorporated into the continuous VHG fermentation system to in situ remove ethanol produced by Saccharomyces cerevisiae, and the process oscillation was also attenuated, but restored after the gas stripping was interrupted. Experimental results indicated that ethanol inhibition rather than osmotic stress on yeast cells is one of the main factors triggering the process oscillation under the

  7. Biohydrogen production from xylose at extreme thermophilic temperatures (70 degrees C) by mixed culture fermentation.

    Science.gov (United States)

    Kongjan, Prawit; Min, Booki; Angelidaki, Irini

    2009-03-01

    Biohydrogen production from xylose at extreme thermophilic temperatures (70 degrees C) was investigated in batch and continuous-mode operation. Biohydrogen was successfully produced from xylose by repeated batch cultivations with mixed culture received from a biohydrogen reactor treating household solid wastes at 70 degrees C. The highest hydrogen yield of 1.62+/-0.02 mol-H2/mol-xylose(consumed) was obtained at initial xylose concentration of 0.5 g/L with synthetic medium amended with 1g/L of yeast extract. Lower hydrogen yield was achieved at initial xylose concentration higher than 2g/L. Addition of yeast extract in the cultivation medium resulted in significant improvement of hydrogen yield. The main metabolic products during xylose fermentation were acetate, ethanol, and lactate. The specific growth rates were able to fit the experimental points relatively well with Haldane equation assuming substrate inhibition, and the following kinetic parameters were obtained: the maximum specific growth rate (mu(max)) was 0.17 h(-1), the half-saturation constant (K(s)) was 0.75g/L, and inhibition constant (K(i)) was 3.72 g/L of xylose. Intermittent N2 sparging could enhance hydrogen production when high hydrogen partial pressure (> 0.14 atm) was present in the headspace of the batch reactors. Biohydrogen could be successfully produced in continuously stirred reactor (CSTR) operated at 72-h hydraulic retention time (HRT) with 1g/L of xylose as substrate at 70 degrees C. The hydrogen production yield achieved in the CSTR was 1.36+/-0.03 mol-H2/mol-xylose(sonsumed), and the production rate was 62+/-2 ml/d x L(reactor). The hydrogen content in the methane-free mixed gas was approximately 31+/-1%, and the rest was carbon dioxide. The main intermediate by-products from the effluent were acetate, formate, and ethanol at 4.25+/-0.10, 3.01+/-0.11, and 2.59+/-0.16 mM, respectively.

  8. Effects of culture conditions on spore types of Clonostachys rosea 67-1 in submerged fermentation.

    Science.gov (United States)

    Sun, M H; Chen, Y M; Liu, J F; Li, S D; Ma, G Z

    2014-04-01

    The promising biocontrol isolate Clonostachys rosea 67-1 was investigated to clarify the effects of culture conditions on chlamydospore production in submerged fermentation. Culture conditions significantly affected both performance and types of C. rosea sporulation. C. rosea 67-1 was hard to generate chlamydospores under conventional conditions. However, the proportion of resistant spores increased to 17·4 and 15·5% in PD and rice meal media, respectively, in 8 days. Chlamydospore productivity was boosted (>threefold) with the addition of 50-200 mg l(-1) CuSO4 . The pH of the medium played a vital role in 67-1 sporulation. The percentage of chlamydospores decreased rapidly with increased pH (88·1% at pH 3·0 to 1·0% at pH 6·5). The optimal pH for conidia production was 6·0-6·5, at which chlamydospore forming was strongly inhibited. Regulating pH during fermentation contributed to improving output and proportion of resistant spores. When 67-1 was inoculated into broth with an initial pH of 6·5, followed by adjustment to pH 3·5 after 48 h, the number of chlamydospores reached 1·1 × 10(8) ml(-1). The impact of temperature and rotational speed was also analysed; an ultimate capacity of chlamydospores was achieved at 30°C and the speed above 120 rev min(-1) (P culture conditions on performance and types of C. rosea sporulation and subsequently inadequate research on the techniques for chlamydospore production. In addressing these concerns, this study provides a unique insight into the manipulation of C. rosea sporulation and chlamydospore fermentation of the biocontrol fungus. © 2013 The Society for Applied Microbiology.

  9. Indigenous Starter Cultures to Improve Quality of Artisanal Dry Fermented Sausages from Chaco (Argentina

    Directory of Open Access Journals (Sweden)

    Noelia Z. Palavecino Prpich

    2015-01-01

    Full Text Available Lactic acid bacteria (LAB and coagulase negative cocci (CNC were isolated from artisanal dry sausages sampled from the northeastern region of Chaco, Argentina. In order to evaluate their performance in situ and considering technological features of the isolated strains, two mixed selected autochthonous starter cultures (SAS were designed: (i SAS-1 (Lactobacillus sakei 487 + Staphylococcus vitulinus C2 and (ii SAS-2 (L. sakei 442 + S. xylosus C8. Cultures were introduced into dry sausage manufacturing process at a local small-scale facility. Microbiological and physicochemical parameters were monitored throughout fermentation and ripening periods, while sensory attributes of the final products were evaluated by a trained panel. Lactic acid bacteria revealed their ability to colonize and adapt properly to the meat matrix, inhibiting the growth of spontaneous microflora and enhancing safety and hygienic profile of the products. Both SAS showed a beneficial effect on lipid oxidation and texture of the final products. Staphylococcus vitulinus C2, from SAS-1, promoted a better redness of the final product. Sensory profile revealed that SAS addition preserved typical sensory attributes. Introduction of these cultures could provide an additional tool to standardize manufacturing processes aiming to enhance safety and quality while keeping typical sensory attributes of regional dry fermented sausages.

  10. Indigenous Starter Cultures to Improve Quality of Artisanal Dry Fermented Sausages from Chaco (Argentina)

    Science.gov (United States)

    Palavecino Prpich, Noelia Z.; Castro, Marcela P.; Cayré, María E.; Garro, Oscar A.; Vignolo, Graciela M.

    2015-01-01

    Lactic acid bacteria (LAB) and coagulase negative cocci (CNC) were isolated from artisanal dry sausages sampled from the northeastern region of Chaco, Argentina. In order to evaluate their performance in situ and considering technological features of the isolated strains, two mixed selected autochthonous starter cultures (SAS) were designed: (i) SAS-1 (Lactobacillus sakei 487 + Staphylococcus vitulinus C2) and (ii) SAS-2 (L. sakei 442 + S. xylosus C8). Cultures were introduced into dry sausage manufacturing process at a local small-scale facility. Microbiological and physicochemical parameters were monitored throughout fermentation and ripening periods, while sensory attributes of the final products were evaluated by a trained panel. Lactic acid bacteria revealed their ability to colonize and adapt properly to the meat matrix, inhibiting the growth of spontaneous microflora and enhancing safety and hygienic profile of the products. Both SAS showed a beneficial effect on lipid oxidation and texture of the final products. Staphylococcus vitulinus C2, from SAS-1, promoted a better redness of the final product. Sensory profile revealed that SAS addition preserved typical sensory attributes. Introduction of these cultures could provide an additional tool to standardize manufacturing processes aiming to enhance safety and quality while keeping typical sensory attributes of regional dry fermented sausages. PMID:26955636

  11. Polyhydroxyalkanoates (PHAs) production from fermented cheese whey by using a mixed microbial culture.

    Science.gov (United States)

    Colombo, Bianca; Pepè Sciarria, Tommy; Reis, Maria; Scaglia, Barbara; Adani, Fabrizio

    2016-10-01

    Two fermented cheese wheys (FCW), FCW1 composed of lactic, acetic and butyric acids in the proportion of 58/16/26 (% CODOrganic Acid (OA)) and FCW2 composed of acetic, propionic, butyric, lactic and valeric acids in the proportion of 58/19/13/6/4 (% CODOA) were used to produce polyhydroxyalkanoates (PHAs) by using a pre-selected mixed microbial culture (MMC). PHA accumulation gave for fermented FCW1 a PHA yield (Ytot) of 0.24±0.02mgCODPHAmgCODSolubleSubstrate(SS)(-1) and a total PHA production, referred to the substrate used, of 60gPHAkgcheesewheyTotalSolids(TS)(-1). For fermented FCW2 results were: PHA yield (Ytot) of 0.42±0.03mgCODPHAmgCODSS(-1) and PHA from a substrate of 70gPHAkgcheesewheyTS(-1). Qualitatively, PHAs from FCW1 was made up exclusively of 3-hydroxybutyrate (HB), while those obtained from FCW2 were composed of 40% of 3-hydroxyvalerate (HV) and 60% of HB. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Change of lactose content after milk fermentation using various microbial cultures

    Directory of Open Access Journals (Sweden)

    Ivana Vinko

    2011-06-01

    Full Text Available The purpose of this study was to determine lactose and lactic acid content and acidity changes in typified milk prior to fermentation and in dairy products on 1st and 28th day of their storage at 8 °C in cold environment. In this study 5 different dairy products were observed: yogurt, extra lactose yogurt, bifido milk, sour cream and sour milk. The enzymatic method for determination of lactose has been used. The biggest change in lactose and lactic acid content, according to study results, has happened in the process of fermentation, as expected. About 16-20 % of lactose has been converted by mesophilus, while significantly bigger part (round 30 % of lactose to lactic acid has been converted by thermophilus. The smallest part of lactose conversion was performed by Bifidobacterium therapy culture (just 15 % after the first day and 19 % on 28th day of cold storage which is due to the greater adjustment period of Bifidobacterium in milk for lactose fermentation.

  13. Phenolic trend and hygienic quality of green table olives fermented with Lactobacillus plantarum starter culture.

    Science.gov (United States)

    Benincasa, Cinzia; Muccilli, Serena; Amenta, Margherita; Perri, Enzo; Romeo, Flora V

    2015-11-01

    In this paper, four different olive cultivars from Southern Italy, Carolea, Cassanese, Nocellara del Belice, Nocellara Messinese table olives, produced according to traditional fermentation processes, were evaluated with the aim of assessing the effect of selected starter cultures on growth of bacterial population and on olive phenols during fermentation. Only Cassanese and Nocellara del Belice inoculated samples reached a safe pH value under 4.6 after 90 days while maintaining it until the end of storage. The most representative phenols in brine samples analysed by HPLC-MS/MS were hydroxytyrosol and verbascoside. Among the analysed phenols, only hydroxytyrosol, caffeic acid and ferulic acid always increased during fermentation, while the others increased up to 90-120 days and then decreased. The Principal Component Analysis (PCA) performed on pH and phenol values highlighted three clusters of olive cultivars. Throughout the brining period, lactic acid bacteria were always present while staphylococci and coliform bacteria disappeared after 30 and 90 days, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Sequential culture with Torulaspora delbrueckii and Saccharomyces cerevisiae and management of fermentation temperature to improve cherry wine quality.

    Science.gov (United States)

    Sun, Shu Yang; Gong, Han Sheng; Zhao, Yu Ping; Liu, Wen Li; Jin, Cheng Wu

    2016-04-01

    There has been limited research on the use of non-Saccharomyces yeasts for the production of cherry wines. This work used an autochthonous Torulaspora delbrueckii strain 49 (TD49) in association with a commercial S. cerevisiae RC212 yeast, to investigate the effect of multi-starter culture (sequential inoculation and simultaneous inoculation) and fermentation temperature on the quality of cherry wines. Both TD49 and RC212 proliferated during alcoholic fermentation (AF) under sequential inoculation conditions, whereas in the case of simultaneous inoculation, TD49 increased slowly at first and then declined sharply near the fermentation end. The analytical profile showed that both mixed fermentations produced lower levels of volatile acidy and higher levels of aromatic compounds than those from RC212 mono-culture. During sensory analysis, wines from sequential fermentation obtained the highest score, mainly due to the higher intensity in 'fruity' and 'floral' characters. As for the influence of temperature, a low temperature (20 °C) enhanced TD49 persistence during AF, but the sensory quality decreased anyway; 30 °C resulted in decreases in most measured descriptors. Therefore, 25 °C was selected as the best culture temperature. TD49/RC212 sequential inoculation and fermentation at 25 °C significantly enhanced the cherry wine quality. © 2015 Society of Chemical Industry.

  15. Cosmeceutical potentials and bioactive compounds of rice bran fermented with single and mix culture of Aspergillus oryzae and Rhizopus oryzae

    Directory of Open Access Journals (Sweden)

    Dang Lelamurni Abd Razak

    2017-04-01

    Full Text Available In the present study, rice bran, one of the most abundant agricultural by-products in Malaysia, was fermented with single and mixed cultures of Aspergillus oryzae and Rhizopus oryzae. The fermented rice bran extracts were tested for their functional properties and compared to the non-fermented counterparts. Antioxidant activities as well as phenolics and organic acid contents were evaluated. Skincare-related functionalities were also tested by evaluating tyrosinase and elastase inhibition activities. Tyrosinase inhibition activity, measured to determine the anti-pigmentation effect of extracts, was found to be the highest in the extract of rice bran fermented with A. oryzae (56.18% compared to other extracts. In determining the anti-aging effect of fermented rice bran extracts, the same extract showed the highest elastase inhibition activity with a value of 60.52%. Antioxidant activities were found to be highest in the mix-cultured rice bran extract. The results of phenolic and organic acid content were varied; the major phenolic acid detected was ferulic acid with a value of 43.19 μg/ml in the mix-cultured rice bran extract. On the other hand, citric acid was the major organic acid detected, with the highest content found in the same extract (214.6 mg/g. The results of this study suggest that the fermented rice bran extracts may have the potential to be further exploited as ingredients in cosmetics as well as in antioxidant-rich products.

  16. Comparative technoeconomic analysis of a softwood ethanol process featuring posthydrolysis sugars concentration operations and continuous fermentation with cell recycle.

    Science.gov (United States)

    Schneiderman, Steven J; Gurram, Raghu N; Menkhaus, Todd J; Gilcrease, Patrick C

    2015-01-01

    Economical production of second generation ethanol from Ponderosa pine is of interest due to widespread mountain pine beetle infestation in the western United States and Canada. The conversion process is limited by low glucose and high inhibitor concentrations resulting from conventional low-solids dilute acid pretreatment and enzymatic hydrolysis. Inhibited fermentations require larger fermentors (due to reduced volumetric productivity) and low sugars lead to low ethanol titers, increasing distillation costs. In this work, multiple effect evaporation (MEE) and nanofiltration (NF) were evaluated to concentrate the hydrolysate from 30 g/l to 100, 150, or 200 g/l glucose. To ferment this high gravity, inhibitor containing stream, traditional batch fermentation was compared with continuous stirred tank fermentation (CSTF) and continuous fermentation with cell recycle (CSTF-CR). Equivalent annual operating cost (EAOC = amortized capital + yearly operating expenses) was used to compare these potential improvements for a local-scale 5 MGY ethanol production facility. Hydrolysate concentration via evaporation increased EAOC over the base process due to the capital and energy intensive nature of evaporating a very dilute sugar stream; however, concentration via NF decreased EAOC for several of the cases (by 2 to 15%). NF concentration to 100 g/l glucose with a CSTF-CR was the most economical option, reducing EAOC by $0.15 per gallon ethanol produced. Sensitivity analyses on NF options showed that EAOC improvement over the base case could still be realized for even higher solids removal requirements (up to two times higher centrifuge requirement for the best case) or decreased NF performance. © 2015 American Institute of Chemical Engineers.

  17. Continuous fermentative hydrogen production from cheese whey wastewater under thermophilic anaerobic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Azbar, Nuri; Cetinkaya Dokgoez, F. Tuba; Keskin, Tugba; Korkmaz, Kemal S.; Syed, Hamid M. [Bioengineering Department, Faculty of Engineering, Ege University, EBILTEM, Bornova, 35100 Izmir (Turkey)

    2009-09-15

    Hydrogen (H{sub 2}) production from cheese processing wastewater via dark anaerobic fermentation was conducted using mixed microbial communities under thermophilic conditions. The effects of varying hydraulic retention time (HRT: 1, 2 and 3.5 days) and especially high organic load rates (OLR: 21, 35 and 47 g chemical oxygen demand (COD)/l/day) on biohydrogen production in a continuous stirred tank reactor were investigated. The biogas contained 5-82% (45% on average) hydrogen and the hydrogen production rate ranged from 0.3 to 7.9 l H{sub 2}/l/day (2.5 l/l/day on average). H{sub 2} yields of 22, 15 and 5 mmol/g COD (at a constant influent COD of 40 g/l) were achieved at HRT values of 3.5, 2, and 1 days, respectively. On the other hand, H{sub 2} yields were monitored to be 3, 9 and 6 mmol/g COD, for OLR values of 47, 35 and 21 g COD/l/day, when HRT was kept constant at 1 day. The total measurable volatile fatty acid concentration in the effluent (as a function of influent COD) ranged between 118 and 27,012 mg/l, which was mainly composed of acetic acid, iso-butyric acid, butyric acid, propionic acid, formate and lactate. Ethanol and acetone production was also monitored from time to time. To characterize the microbial community in the bioreactor at different HRTs, DNA in mixed liquor samples was extracted immediately for PCR amplification of 16S RNA gene using eubacterial primers corresponding to 8F and 518R. The PCR product was cloned and subjected to DNA sequencing. The sequencing results were analyzed by using MegaBlast available on NCBI website which showed 99% identity to uncultured Thermoanaerobacteriaceae bacterium. (author)

  18. Effects of alimet on nutrient digestibility, bacterial protein synthesis, and ruminal disappearance during continuous culture.

    Science.gov (United States)

    Vázquez-Añón, M; Cassidy, T; McCullough, P; Varga, G A

    2001-01-01

    A dual effluent continuous culture system was used to investigate the effects of inclusion of Alimet (Novus International, Inc., St. Louis, MO) feed supplement [an 88% aqueous solution of dl, 2-hydroxy-4-(methylthio) butanoic acid (HMB)] in the diet on nutrient digestibility, bacterial protein synthesis and ruminal disappearance of HMB. Four fermenters were fed three times daily a basal diet that consisted of 50% grain mixture and 50% forage for 9 d. In experiment 1, four concentrations of HMB (0, 0.20, 0.77, and 1.43% DM basis) were added to the diet and fed to the fermenters twice daily. In experiment 2, two concentrations of dietary HMB (0 and 0.88% DM basis) were fed twice daily and evaluated with two solids retention times (16.7 vs. 25.0 h) and two liquid dilution rates (0.15 vs. 0.125 h(-1)). Increasing the amount of HMB in the diet did not affect nutrient digestibility, volatile fatty acid concentrations, or ruminal escape of HMB. Bacterial protein synthesis was improved with the addition of HMB during high and low retention times. The extent of HMB escaping ruminal degradation ranged from 21.6 to 43.2% and was highest at the lower retention time. It can be concluded that a fraction of HMB survives rumen microbial degradation and, therefore, provides a rumen-protected form of methionine at the same time that it improves bacterial protein synthesis.

  19. Cell-to-cell contact and antimicrobial peptides play a combined role in the death of Lachanchea thermotolerans during mixed-culture alcoholic fermentation with Saccharomyces cerevisiae.

    Science.gov (United States)

    Kemsawasd, Varongsiri; Branco, Patrícia; Almeida, Maria Gabriela; Caldeira, Jorge; Albergaria, Helena; Arneborg, Nils

    2015-07-01

    The roles of cell-to-cell contact and antimicrobial peptides in the early death of Lachanchea thermotolerans CBS2803 during anaerobic, mixed-culture fermentations with Saccharomyces cerevisiae S101 were investigated using a commercially available, double-compartment fermentation system separated by cellulose membranes with different pore sizes, i.e. 1000 kDa for mixed- and single-culture fermentations, and 1000 and 3.5-5 kDa for compartmentalized-culture fermentations. SDS-PAGE and gel filtration chromatography were used to determine an antimicrobial peptidic fraction in the fermentations. Our results showed comparable amounts of the antimicrobial peptidic fraction in the inner compartments of the mixed-culture and 1000 kDa compartmentalized-culture fermentations containing L. thermotolerans after 4 days of fermentation, but a lower death rate of L. thermotolerans in the 1000 kDa compartmentalized-culture fermentation than in the mixed-culture fermentation. Furthermore, L. thermotolerans died off even more slowly in the 3.5-5 kDa than in the 1000 kDa compartmentalized-culture fermentation, which coincided with the presence of less of the antimicrobial peptidic fraction in the inner compartment of that fermentation than of the 1000 kDa compartmentalized-culture fermentation. Taken together, these results indicate that the death of L. thermotolerans in mixed cultures with S. cerevisiae is caused by a combination of cell-to-cell contact and antimicrobial peptides. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Transcriptional profiling of Brazilian Saccharomyces cerevisiae strains selected for semi-continuous fermentation of sugarcane must.

    Science.gov (United States)

    Brown, Neil A; de Castro, Patrícia A; de Castro Pimentel Figueiredo, Bárbara; Savoldi, Marcela; Buckeridge, Marcos S; Lopes, Mário L; de Lima Paullilo, Silene C; Borges, Eduardo P; Amorim, Henrique V; Goldman, Maria H S; Bonatto, Diego; Malavazi, Iran; Goldman, Gustavo H

    2013-05-01

    Brazil played a pioneering role in the global establishment of the sugarcane bioethanol industry. The bioethanol fermentation process currently used in Brazil is unique due to the acid wash and recycling of yeast cells. Two, industrially adopted, wild yeast strains, CAT-1 and PE-2, have become the most widely used in Brazil. How these strains respond to the unique fermentation process is poorly understood. The improved performance of CAT-1 and PE-2 is hypothesised to be related to enhanced stress tolerance. This study presents a genome-wide analysis of the CAT-1 and PE-2 transcriptomes during a small-scale fermentation process that mimicked the industrial conditions. The common and unique transcriptional responses of the two strains to the Brazilian fermentation process were identified. Environmental stress response genes were up-regulated postfermenter feeding, demonstrating the impact of the prior acid wash and high glucose environment. Cell wall and oxidative stress tolerance were subsequently demonstrated to be enhanced for the industrial strains. Conversely, numerous genes involved in protein synthesis were down-regulated at the end of fermentation revealing the later impact of ethanol-induced stress. Subsequently, the industrial strains demonstrated a greater tolerance of ethanol and the disruption of endoplasmic reticulum homoeostasis. This increased ethanol tolerance was finally correlated with an increased unfolded protein response and increased HAC1 splicing. © 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  1. Effect of cultural conditions on antrodin C production by basidiomycete Antrodia camphorata in solid-state fermentation.

    Science.gov (United States)

    Xia, Yongjun; Wang, Yuanlong; Zhang, Bobo; Xu, Ganrong; Ai, Lianzhong

    2014-01-01

    Antrodia camphorata is a medicinal fungus and antrodin C is one of the main bioactive components of A. camphorata in the submerged fermentation (SmF). To optimize the culture conditions, the factors influencing the production of antrodin C by A. camphorata under solid-state fermentation (SSF) were investigated in this study. Different solid substrates and external nitrogen sources were tested for their efficiency in producing antrodin C. The response surface methodology was applied to evaluate the influence of several variables, namely, the concentrations of soybean meal, initial moisture content, and inoculum density on antrodin C production in solid-state fermentation. The experimental results show that the optimum fermentation medium for antrodin C production by A. camphorata was composed of 0.578 g soybean meal, 0.05 g Na2 HPO4 , 0.05 g MgSO4 for 100 g rice, with 51.83% initial moisture content, 22 day culture time, 28 °C culture temperature, and 35.54% inoculum density. At optimized conditions, 6,617.36 ± 92.71 mg kg(-1) yield of antrodin C was achieved. Solid-state fermentation is one good cultural method to improve the production of antrodin C by A. camphorata. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

  2. On-farm implementation of a starter culture for improved cocoa bean fermentation and its influence on the flavour of chocolates produced thereof.

    Science.gov (United States)

    Lefeber, Timothy; Papalexandratou, Zoi; Gobert, William; Camu, Nicholas; De Vuyst, Luc

    2012-06-01

    Cocoa bean fermentations controlled by means of starter cultures were introduced on several farms in two different cocoa-producing regions (West Africa and Southeast Asia). Two starter culture mixtures were tested, namely one composed of Saccharomyces cerevisiae H5S5K23, Lactobacillus fermentum 222, and Acetobacter pasteurianus 386B (three heaps and one box), and another composed of L. fermentum 222 and A. pasteurianus 386B (seven heaps and one box). In all starter culture-added cocoa bean fermentation processes, the inoculated starter culture species were able to outgrow the natural contamination of the cocoa pulp-bean mass and they prevailed during cocoa bean fermentation. The application of both added starter cultures resulted in fermented dry cocoa beans that gave concomitant milk and dark chocolates with a reliable flavour, independent of cocoa-producing region or fermentation method. The addition of the lactic acid bacterium (LAB)/acetic acid bacterium (AAB) starter culture to the fermenting cocoa pulp-bean mass accelerated the cocoa bean fermentation process regarding citric acid conversion and lactic acid production through carbohydrate fermentation. For the production of a standard bulk chocolate, the addition of a yeast/LAB/AAB starter culture was necessary. This enabled an enhanced and consistent ethanol production by yeasts for a successful starter culture-added cocoa bean fermentation process. This study showed possibilities for the use of starter cultures in cocoa bean fermentation processing to achieve a reliably improved fermentation of cocoa pulp-bean mass that can consistently produce high-quality fermented dry cocoa beans and flavourful chocolates produced thereof. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. A Study On Effect Of Added Neutralisers On Starter Culture Growth In Fermented Milks

    Directory of Open Access Journals (Sweden)

    Rajanna.M

    2017-06-01

    Full Text Available The Dairy starter culture is referred to carefully selection of desirable microorganisms. Those are intentionally added to milk during conversion into cheese dahi yoghurt and other fermented dairy products to bring about specific changes in the appearance body and texture flavor and desired organoleptic characteristics of the final product. The quality of milk itself has an important bearing on the growth of starter organisms. The mastitis milk has abnormal in composition and such milk with high salt concentration does not support the growth of starter culture that leads to production of poor quality of fermented dairy products with week body.. The presence of certain neutralizing substances performed in milk has found to interfere with growth of starters. There was a definite lag in the growth of the starter organisms as well as acid development when neutralizers were added to raw milk samples. This may be due to the bacteriostatic effect of added neutralizers. But discrepancy was seen to the greatest extent in the case of neutralized mastitis and highly advanced lactation milks and to a lesser degree on the early lactation milk obtained on the 4th and 5th days.

  4. Development of High-Productivity Continuous Ethanol Production using PVA-Immobilized Zymomonas mobilis in an Immobilized-Cells Fermenter

    Directory of Open Access Journals (Sweden)

    Nurhayati Nurhayati

    2015-07-01

    Full Text Available Ethanol as one of renewable energy was being considered an excellent alternative clean-burning fuel to replace gasoline. Continuous ethanol fermentation systems had offered important economic advantages compared to traditional systems. Fermentation rates were significantly improved, especially when continuous fermentation was integrated with cell immobilization techniques to enrich the cells concentration in fermentor. Growing cells of Zymomonas mobilis immobilized in polyvinyl alcohol (PVA gel beads were employed in an immobilized-cells fermentor for continuous ethanol fermentation from glucose. The glucose loading, dilution rate, and cells loading were varied in order to determine which best condition employed in obtaining both high ethanol production and low residual glucose with high dilution rate. In this study, 20 g/L, 100 g/L, 125 g/L and 150 g/L of glucose concentration and 20% (w/v, 40% (w/v and 50% (w/v of cells loading were employed with range of dilution rate at 0.25 to 1 h-1. The most stable production was obtained for 25 days by employing 100 g/L of glucose loading. Meanwhile, the results also exhibited that 125 g/L of glucose loading as well as 40% (w/v of cells loading yielded high ethanol concentration, high ethanol productivity, and acceptable residual glucose at 62.97 g/L, 15.74 g/L/h and 0.16 g/L, respectively. Furthermore, the dilution rate of 4 hour with 100 g/L and 40% (w/v of glucose and cells loading was considered as the optimum condition with ethanol production, ethanol productivity and residual glucose obtained were 49.89 g/L, 12.47 g/L/h, and 2.04 g/L, respectively. This recent study investigated ethanol inhibition as well. The present research had proved that high sugar concentration was successfully converted to ethanol. These achieved results were promising for further study.

  5. Impact of microbial cultures on proteolysis and release of bioactive peptides in fermented milk.

    Science.gov (United States)

    Chaves-López, Clemencia; Serio, Annalisa; Paparella, Antonello; Martuscelli, Maria; Corsetti, Aldo; Tofalo, Rosanna; Suzzi, Giovanna

    2014-09-01

    This study aimed at evaluating co-cultures of selected microorganisms for their proteolytic activity and capability to produce fermented milk enriched with ACE-inhibitory (ACEI) peptides. Selected yeasts (Torulaspora delbruekii KL66A, Galactomyces geotrichum KL20B, Pichia kudriavzevii KL84A and Kluyveromyces marxianus KL26A) and lactic acid bacteria strains (Lactobacillus plantarum LAT03, Lb. plantarum KLAT01 and the not virulent Enterococcus faecalis KE06) were screened as single cultures for their capacity of releasing ACEI peptides without producing bitter taste. Three strains cultures (yeast, Lb. plantarum and E. faecalis) were performed to evaluate the combined impact on microbial growth, lactic acid production, citric acid consumption, proteolysis, ACEI activity, and bitter taste after 36 h of fermentation at 28 °C. While G. geotrichum KL20B showed a strong stimulating effect on Lb. plantarum strains and the production of peptides with ACEI activity, the presence of T. delbruekii KL26A in the cultures was deleterious both to ACEI activity and product taste. The most effective combination was P. kudriavzevii KL84A, Lb. plantarum LAT3, E. faecalis KL06, which showed the highest ACEI activity (IC50 = 30.63 ± 1.11 μg ml(-1)) and gave no bitter taste for 7 days at 6 °C. Our results highlight the importance of choosing the strains combination carefully, to obtain a high yield of ACEI activity without bitter taste. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Effect of temperature on microbial composition of starter culture for Chinese light aroma style liquor fermentation.

    Science.gov (United States)

    Wang, H Y; Xu, Y

    2015-01-01

    Light aroma style liquor is one of the basic types of Chinese liquor and is produced with a special technique of using a combination of three types of Daqu as starter culture. The succession of incubation temperature, a main operating parameter, and microbial composition in Daqu were investigated during the manufacturing process. The most significant difference in temperature occurred during the middle stage at which the highest and the lowest temperatures were detected in Houhuo (HH) and Qingcha (QC), respectively. It was shown that for the counting data, the population of fungi was identical and that of bacteria was different between three types of Daqu. According to analysis results of microbial community structure using PCR-denaturing gradient gel electrophoresis (PCR-DGGE), lactic acid bacteria were one of the dominant bacterial groups in all of Daqu and fungal diversity in QC was higher than that in HH and Hongxin (HX). The difference in incubation temperature led to the accumulation of different heat-tolerant and heat-sensitive fungi in the completed Daqu. PCA of DGGE profiles revealed that microbial community structure was distinct between three types of Daqu. It was presumed that temperature might play a decisive role in the formation of micro-organism composition in starter cultures. The usage of a combination of three types of Daqu including Qingcha, Hongxin and Houhuo as starter culture is an important characteristic of production technology of Chinese light aroma style liquor. Micro-organisms from the environment naturally inoculated in Daqu are propagated to form the special microbial community under the control of several operating parameters, especially temperature, and finally play various roles in the fermentation process of liquor. An in-depth study of the relationship between incubation temperature and microbiota in Daqu during the manufacturing is fundamental to understand this complicated process and to prepare high-quality starter culture for

  7. Fermented sausage production using E. faecium as starter culture: Physicochemical and microbiological profile, sensorial acceptance and cellular viability

    Directory of Open Access Journals (Sweden)

    Catharina Calochi Pires de Carvalho

    2017-09-01

    Full Text Available Fermented sausages are defined as a mixture of lean meat and fat, curing salts, sucrose and spices, stuffed in a natural or artificial casing and submitted to fermentation and air-drying process. Starter culture and ripening process may affect the quality and acceptability of the final product. Current research evaluates the use of Enterococcus faecium as starter culture in fermented sausage production and its physicochemical and microbiological profile during maturation process, coupled to sausage sensory acceptance after ripening. Enterococcus faecium showed 10.9 log CFU g-1 and remained viable after the ripening period with 8.32 log CFU g-1. Fermented sausage was monitored during the ripening period by physicochemical (pH control, water activity and weight loss and microbiological (analysis of coagulase-positive Staphylococcus, coliforms and Salmonella spp. analyses. All tests complied with standards established by Brazilian legislation and did not interfere in final product quality. Results showed that E. faecium was resistant to curing salt and sodium chloride, maintaining its viability during ripening and conferring beneficial effects on fermented sausage technological characteristics. E. faecium also proved to be in vitro resistant to simulate passage through the human digestive tract. Fermented sausage containing E. faecium had better sensory acceptance than commercial sausage evaluated.

  8. Development of Fermented Mare’s Milk Using Mixed Probiotic Cultures

    Directory of Open Access Journals (Sweden)

    T. W. Murti

    2016-04-01

    Full Text Available Mare’s milk has good nutrient composition for human being in the form of natural milk or milk products. It can be used to replace cow’s milk, especially in the regions outside of Java Island which are rarely found dairy cow. This study had an objective to develop fermented mare’s milk by using mixed cultures of probiotic bacteria i.e. Lactobacillus acidophilus (A, Bifidobacterium longum (B, and Lactobacillus casei (C. The cultures of two probiotic bacteria AB and BC had been developed as well as three probiotic bacteria ABC culture. The mixed cultures (AB, BC and ABC were prepared in single culture then cultivated in mixed culture as total 10% v/v of mare’s milk used and was incubated at 39°C for 9 h. The pH, acidity and bacterial count, each of them was analyzed in every 3 h of incubation time, while the organic acid and sensory tests were conducted at the end of 9 h of incubation. The results showed that the growth of mixed probiotic bacteria culture BC and ABC had better pH value that was around 3 compared with AB around 4.5. This showed that the cooperation between bacteria was different in each different combinations. The number of bacteria also increased sharply between 3-6 h of incubation time and 6-9 incubation time (AB and BC along with the increased lactic acid, but the acetic acid decreased from 1750 mg/L to 1500 mg/L. The result of sensory test showed low acceptability of trained panelists. It is concluded that mixed cultures, using two or three probiotic bacteria (L. acidophilus, B. longum, and L. casei could grow in mare’s milk. The change of the biochemical patterns indicated a commensalism cooperation among bacteria used. It was therefore the fermented mare’s milk using these probiotic bacteria were not well accepted by entrained panelists.

  9. Optimization of a fermented soy product formulation with a kefir culture and fiber using a simplex-centroid mixture design.

    Science.gov (United States)

    Baú, Tahis Regina; Garcia, Sandra; Ida, Elza Iouko

    2013-12-01

    The objective of this work was to optimize a fermented soy product formulation with kefir and soy, oat and wheat fibers and to evaluate the fiber and product characteristics. A simplex-centroid mixture design was used for the optimization. Soymilk, soy, oat and wheat fiber mixtures, sucrose and anti-foaming agent were used for the formulation, followed by thermal treatment, cooling and the addition of flavoring. Fermentation was performed at 25 °C with a kefir culture until a pH of 4.5 was obtained. The products were cooled, homogenized and stored for analysis. From the mathematical models and variables response surface and desirability an optimal fermented product was formulated containing 3% (w/w) soy fiber. Compared with the other formulations, soy fermented product with 3% soy fiber had the best acidity, viscosity, syneresis, firmness and Lactococcus lactis count.

  10. Effective multiple stages continuous acetone-butanol-ethanol fermentation by immobilized bioreactors: Making full use of fresh corn stalk.

    Science.gov (United States)

    Chang, Zhen; Cai, Di; Wang, Yong; Chen, Changjing; Fu, Chaohui; Wang, Guoqing; Qin, Peiyong; Wang, Zheng; Tan, Tianwei

    2016-04-01

    In order to make full use of the fresh corn stalk, the sugar containing juice was used as the sole substrate for acetone-butanol-ethanol production without any nutrients supplement, and the bagasse after squeezing the juice was used as the immobilized carrier. A total 21.34g/L of ABE was produced in batch cells immobilization system with ABE yield of 0.35g/g. A continuous fermentation containing three stages with immobilized cells was conducted and the effect of dilution rate on fermentation was investigated. As a result, the productivity and ABE solvents concentration reached 0.80g/Lh and 19.93g/L, respectively, when the dilution rate in each stage was 0.12/h (corresponding to a dilution rate of 0.04/h in the whole system). And the long-term operation indicated the continuous multiple stages ABE fermentation process had good stability and showed the great potential in future industrial applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Effects of Plant Secondary Metabolites on Methane Production and Fermentation Parameters in In vitro Ruminal Cultures

    Directory of Open Access Journals (Sweden)

    Mihaela Giuburunca

    2014-10-01

    Full Text Available Enteric fermentation process is of concern worldwide for its contribution to global warming. It is known that ruminant animals, due to natural fermentation process contribute substantially to the increase in methane production. Methanogenesis process represents besides its contribution to greenhouse gases emissions an energy loss to the animal. To reduce ruminal methane productions in an ecologically and sustainable way, many attempts have been initiated, such as: uses of chemicals additives or ionophore antibiotics, defaunation process or immunization against ruminal methanogenesis. In the last years, a new strategy has been evaluated whether plant secondary metabolites can be used as natural additives to reduce ruminal methane emissions. The present study has been conducted to investigate the effects of trans-cinnamic, caffeic, p-coumaric acids and catechin hydrate, four plant secondary metabolites (PSMs on methane production and fermentation in in vitro ruminal cultures. The four PSMs were added anaerobically in a 6 mM concentration to 100 ml serum bottles containing 500 mg grass hay as a substrate, 10 ml rumen fluid collected from a fistulated sheep before morning feeding and 40 ml 141 DSM culture medium. The bottles were incubated at 39 ̊C. After 24 h, the following variables were measured: total gas volume, pH, methane and volatile fatty acids (VFAs production. The results showed that caffeic (p = 0.058 and p-coumaric (p = 0.052 acids tended to decrease methane production in comparison to control but the decrease was not statistic significantly at α= 0.05. The other two PSMs had no significant effect on methane production. Addition of PSMs did not affected the total gas volume, the pH and VFAs profile (P>0.05 in relation to the control (no PSM added. In conclusion, caffeic and p-coumaric acids in 6 mM concentration showed some promising effects for decreasing ruminal methane emissions without affecting ruminal fermentation parameters but

  12. Use of continuous lactose fermentation for ethanol production by Kluveromyces marxianus for verification and extension of a biochemically structured model

    DEFF Research Database (Denmark)

    Sansonetti, S.; Hobley, Timothy John; Curcio, S.

    2013-01-01

    production of ms = 0.6029 and me= 0.4218 (C-mol)*(C-mol*h)-1, respectively. True yield coefficients for biomass, ethanol and glycerol production were calculated to be Ytrue sx = 0.114, Ytrue ex = 0.192 and Ysg = 2.250 (C-mol)*(C-mol)-1, respectively. Model calculated maintenance and true yield coefficients......A biochemically structured model has been developed to describe the continuous fermentation of lactose to ethanol by Kluveromyces marxianus and allowed metabolic coefficients to be determined. Anaerobic lactose-limited chemostat fermentations at different dilution rates (0.02 – 0.35 h-1) were...... performed. Species specific rates of consumption/formation, as well as yield coefficients were determined. Ethanol yield (0.655 C-mol ethanol*C-mol lactose-1) was as high as 98 % of theoretical. The modeling procedure allowed calculation of maintenance coefficients for lactose consumption and ethanol...

  13. Fermentative hydrogen production from glucose and starch using pure strains and artificial co-cultures of Clostridium spp.

    Science.gov (United States)

    2012-01-01

    Background Pure bacterial strains give better yields when producing H2 than mixed, natural communities. However the main drawback with the pure cultures is the need to perform the fermentations under sterile conditions. Therefore, H2 production using artificial co-cultures, composed of well characterized strains, is one of the directions currently undertaken in the field of biohydrogen research. Results Four pure Clostridium cultures, including C. butyricum CWBI1009, C. pasteurianum DSM525, C. beijerinckii DSM1820 and C. felsineum DSM749, and three different co-cultures composed of (1) C. pasteurianum and C. felsineum, (2) C. butyricum and C. felsineum, (3) C. butyricum and C. pasteurianum, were grown in 20 L batch bioreactors. In the first part of the study a strategy composed of three-culture sequences was developed to determine the optimal pH for H2 production (sequence 1); and the H2-producing potential of each pure strain and co-culture, during glucose (sequence 2) and starch (sequence 3) fermentations at the optimal pH. The best H2 yields were obtained for starch fermentations, and the highest yield of 2.91 mol H2/ mol hexose was reported for C. butyricum. By contrast, the biogas production rates were higher for glucose fermentations and the highest value of 1.5 L biogas/ h was observed for the co-culture (1). In general co-cultures produced H2 at higher rates than the pure Clostridium cultures, without negatively affecting the H2 yields. Interestingly, all the Clostridium strains and co-cultures were shown to utilize lactate (present in a starch-containing medium), and C. beijerinckii was able to re-consume formate producing additional H2. In the second part of the study the co-culture (3) was used to produce H2 during 13 days of glucose fermentation in a sequencing batch reactor (SBR). In addition, the species dynamics, as monitored by qPCR (quantitative real-time PCR), showed a stable coexistence of C. pasteurianum and C. butyricum during this

  14. Fermentative hydrogen production from glucose and starch using pure strains and artificial co-cultures ofClostridium spp.

    Directory of Open Access Journals (Sweden)

    Masset Julien

    2012-05-01

    Full Text Available Abstract Background Pure bacterial strains give better yields when producing H2 than mixed, natural communities. However the main drawback with the pure cultures is the need to perform the fermentations under sterile conditions. Therefore, H2 production using artificial co-cultures, composed of well characterized strains, is one of the directions currently undertaken in the field of biohydrogen research. Results Four pure Clostridium cultures, including C. butyricum CWBI1009, C. pasteurianum DSM525, C. beijerinckii DSM1820 and C. felsineum DSM749, and three different co-cultures composed of (1 C. pasteurianum and C. felsineum, (2 C. butyricum and C. felsineum, (3 C. butyricum and C. pasteurianum, were grown in 20 L batch bioreactors. In the first part of the study a strategy composed of three-culture sequences was developed to determine the optimal pH for H2 production (sequence 1; and the H2-producing potential of each pure strain and co-culture, during glucose (sequence 2 and starch (sequence 3 fermentations at the optimal pH. The best H2 yields were obtained for starch fermentations, and the highest yield of 2.91 mol H2/ mol hexose was reported for C. butyricum. By contrast, the biogas production rates were higher for glucose fermentations and the highest value of 1.5 L biogas/ h was observed for the co-culture (1. In general co-cultures produced H2 at higher rates than the pure Clostridium cultures, without negatively affecting the H2 yields. Interestingly, all the Clostridium strains and co-cultures were shown to utilize lactate (present in a starch-containing medium, and C. beijerinckii was able to re-consume formate producing additional H2. In the second part of the study the co-culture (3 was used to produce H2 during 13 days of glucose fermentation in a sequencing batch reactor (SBR. In addition, the species dynamics, as monitored by qPCR (quantitative real-time PCR, showed a stable coexistence of C. pasteurianum and C

  15. Adaptation of continuous biogas reactors operating under wet fermentation conditions to dry conditions with corn stover as substrate.

    Science.gov (United States)

    Kakuk, Balázs; Kovács, Kornél L; Szuhaj, Márk; Rákhely, Gábor; Bagi, Zoltán

    2017-08-01

    Corn stover (CS) is the agricultural by-product of maize cultivation. Due to its high abundance and high energy content it is a promising substrate for the bioenergy sector. However, it is currently neglected in industrial scale biogas plants, because of its slow decomposition and hydrophobic character. To assess the maximum biomethane potential of CS, long-term batch fermentations were carried out with various substrate concentrations and particle sizes for 72 days. In separate experiments we adapted the biogas producing microbial community in wet fermentation arrangement first to the lignocellulosic substrate, in Continuous Stirred Tank Reactor (CSTR), then subsequently, by continuously elevating the feed-in concentration, to dry conditions in solid state fermenters (SS-AD). In the batch tests, the produce 90% of the total biomethane yield than the amount of substrate added to the fermentation lowered the specific methane yield. In the CSTR experiment, the daily substrate loading was gradually increased from 1 to 2 g vs /L/day until the system produced signs of overloading. Then the biomass was transferred to SS-AD reactors and the adaptation process was studied. Although the specific methane yields were lower in the SS-AD arrangement (177 mL CH 4 /g vs in CSTR vs. 105 mL in SS-AD), the benefits of process operational parameters, i.e. lower energy consumption, smaller reactor volume, digestate amount generated and simpler configuration, may compensate the somewhat lower yield. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Continuous fermentation and kinetic experiments for the conversion of crude glycerol derived from second-generation biodiesel into 1,3 propanediol and butyric acid

    DEFF Research Database (Denmark)

    Varrone, Cristiano; Floriotis, Georgis; Heggeset, Tonje M. B.

    2017-01-01

    This study investigated the performance of different mixed microbial cultures (MMC) able to ferment crude glycerol generated from animal fat-based biodiesel to produce 1,3 propanediol (1,3 PDO) and butyric acid, under non-sterile conditions. Eight different continuous flow stirred-tank reactors...... (CSTR) were set up with different inoculum types and growth media. The distribution of metabolic products under variable operating conditions was determined. All MMC were characterized from a kinetic point of view and overall stoichiometric reactions were constructed. Changes in the microbial...... communities were monitored by means of Next Generation Sequencing (NGS). Maximum substrate degradation rate reached approximately 110 g/L/d of glycerol (with a productivity of 38 g/L/d and 11 g/L/d for 1,3 PDO and butyric acid, respectively), obtained with an hydraulic retention time of 12 h and 60 g/L feed...

  17. Analysis of microbial community variation during the mixed culture fermentation of agricultural peel wastes to produce lactic acid.

    Science.gov (United States)

    Liang, Shaobo; Gliniewicz, Karol; Gerritsen, Alida T; McDonald, Armando G

    2016-05-01

    Mixed cultures fermentation can be used to convert organic wastes into various chemicals and fuels. This study examined the fermentation performance of four batch reactors fed with different agricultural (orange, banana, and potato (mechanical and steam)) peel wastes using mixed cultures, and monitored the interval variation of reactor microbial communities with 16S rRNA genes using Illumina sequencing. All four reactors produced similar chemical profile with lactic acid (LA) as dominant compound. Acetic acid and ethanol were also observed with small fractions. The Illumina sequencing results revealed the diversity of microbial community decreased during fermentation and a community of largely lactic acid producing bacteria dominated by species of Lactobacillus developed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Development of the Continued Improvement System for Nuclear Safety Culture

    Energy Technology Data Exchange (ETDEWEB)

    Park, H. C.; Park, H. G.; Park, Y. W.; Park, J. Y. [KAIST, Daejeon (Korea, Republic of)

    2016-05-15

    It has been found that almost 80 % of the incidents and accidents occurred recently, such as the Fukushima Daiichi disaster and Domestic SBO accident etc. were analyzed to be caused from human errors. (IAEA NES NG-G-2.1) Which strongly claims the importance of the safety culture system. Accordingly, it should be away from a cursory approach like one-off field survey or Snap shop which were being conducted at present for the continued improvement of safety culture. This study introduces an analytical methodology which approaches the generic form of the safety both consciously and unconsciously expressed with behavior, thoughts, and attitude etc. This study was implemented only for open materials such as Inspection report, incidents and accidents reports, QA documents because of the limitation in accessibility to data. More effective use with securing operational data will be possible in future.

  19. Impact of the co-culture of Saccharomyces cerevisiae–Oenococcus oenion malolactic fermentation and partial characterization of a yeast-derived inhibitory peptidic fraction

    OpenAIRE

    Nehme, Nancy; Mathieu, Florence; Taillandier, Patricia

    2010-01-01

    The present study was aimed to evaluate the impact of the co-culture on the output of malolactic fermentation and to further investigate the reasons of the antagonism exerted by yeasts towards bacteria during sequential cultures. The Saccharomyces cerevisiae D strain/Oenococcus oeni X strain combination was tested by applying both sequential culture and co-culture strategies. This pair was chosen amongst others because the malolactic fermentation was particularly difficult to realize during t...

  20. Use of Tetragenococcus halophilus as a starter culture for flavor improvement in fish sauce fermentation.

    Science.gov (United States)

    Udomsil, Natteewan; Rodtong, Sureelak; Choi, Yeung Joon; Hua, Yanglin; Yongsawatdigul, Jirawat

    2011-08-10

    The potential of Tetragenococcus halophilus as a starter culture for flavor improvement in fish sauce fermentation was elucidated. Four strains of T. halophilus isolated from fish sauce mashes were inoculated to anchovy mixed with 25% NaCl with an approximate cell count of 10(6) CFU/mL. The α-amino content of 6-month-old fish sauce samples inoculated with T. halophilus was 780-784 mM. The addition of T. halophilus MRC10-1-3 and T. halophilus MCD10-5-10 resulted in a reduction of histamine (P Fish sauce inoculated with T. halophilus showed high contents of total amino acids with predominantly high glutamic acid. Major volatile compounds in fish sauce were 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, and benzaldehyde. T. halophilus-inoculated fish sauce samples demonstrated the ability to reduce dimethyl disulfide, a compound contributing to a fecal note. The use of T. halophilus for fish sauce fermentation improves amino acid profiles and volatile compounds as well as reduces biogenic amine content of a fish sauce product.

  1. Effect of nutrient limitation and two-stage continuous fermentor design on productivities during "Clostridium ragsdalei" syngas fermentation.

    Science.gov (United States)

    Kundiyana, Dimple K; Huhnke, Raymond L; Wilkins, Mark R

    2011-05-01

    The effect of three limiting nutrients, calcium pantothenate, vitamin B(12) and cobalt chloride (CoCl(2)), on syngas fermentation using "Clostridium ragsdalei" was determined using serum bottle fermentation studies. Significant results from the bottle studies were translated into single- and two-stage continuous fermentor designs. Studies indicated that three-way interactions between the three limiting nutrients, and two-way interactions between vitamin B(12) and CoCl(2) had a significant positive effect on ethanol and acetic acid formation. In general, ethanol and acetic acid production ceased at the end of 9 days corresponding to the production of 2.01 and 1.95 gL(-1) for the above interactions. Reactor studies indicated the three-way nutrient limitation in two-stage fermentor showed improved acetic acid (17.51 gg(-1) cells) and ethanol (14.74 gg(-1) cells) yield compared to treatments in single-stage fermentors. These results further support the hypothesis that it is possible to modulate the product formation by limiting key nutrients during C. ragsdalei syngas fermentation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Effect of milk base and starter culture on acidification, texture, and probiotic cell counts in fermented milk processing.

    Science.gov (United States)

    Sodini, I; Lucas, A; Oliveira, M N; Remeuf, F; Corrieu, G

    2002-10-01

    In the present work, the compared effect of milk base and starter culture on acidification, texture, growth, and stability of probiotic bacteria in fermented milk processing, was studied. Two strains of probiotic bacteria were used, Lactobacillus acidophilus LA5 and L. rhamnosus LR35, with two starter cultures. One starter culture consisted only of Streptococcus thermophilus ST7 (single starter culture); the other was a yogurt mixed culture with S. thermophilus ST7 and L. bulgaricus LB12 (mixed starter culture). For the milk base preparation, four commercial dairy ingredients were tested (two milk protein concentrates and two casein hydrolysates). The resulting fermented milks were compared to those obtained with control milk (without enrichment) and milk added with skim milk powder. The performance of the two probiotic strains were opposite. L. acidophilus LA5 grew well on milk but showed a poor stability during storage. L. rhamnosus LR35 grew weakly on milk but was remarkably stable during storage. With the strains tested in this study, the use of the single starter culture and the addition of casein hydrolysate gave the best probiotic cell counts. The fermentation time was of about 11 h, and the probiotic level after five weeks of storage was greater than 106 cfu/ml for L. acidophilus LA5 and 10(7) cfu/ml for L. rhamnosus LR35. However, an optimization of the level of casein hydrolysate added to milk base has to be done, in order to improve texture and flavor when using this dairy ingredient.

  3. Production of potentially probiotic beverages using single and mixed cereal substrates fermented with lactic acid bacteria cultures.

    Science.gov (United States)

    Rathore, Sorbhi; Salmerón, Ivan; Pandiella, Severino S

    2012-05-01

    In the present work, single and mixed cereal substrates were fermented with lactic acid bacteria to study and compare the effect of the media formulation on fermentation parameters. Three cereal flours namely malt, barley and barley mixed with malt (barley-malt) were selected and fermented with two probiotic strains: Lactobacillus plantarum (NCIMB 8826) and Lactobacillus acidophilus (NCIMB 8821). The effect of the single and mixed cereal flour suspensions on the fermentation of these two strains of lactic acid bacteria (LAB) was studied at an incubation temperature of 30 °C for 28 h. It was found that the LAB growth was enhanced in media containing malt and significant amounts of lactic acid were produced (0.5-3.5 g/L). A cell concentration between 7.9 and 8.5 Log₁₀ CFU/mL and a pH below 4.0 was achieved within 6 h of fermentation. Though the cell populations in the mixed culture fermentations of mixed substrates were similar to the ones obtained with single cereal flours, significant differences in the production of lactic acid were observed. These results suggest that the functional and organoleptic properties of these cereal-based probiotic drinks could be considerably modified through changes in the substrate or inocula composition. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Effects of Bacillus subtilis natto and Different Components in Culture on Rumen Fermentation and Rumen Functional Bacteria In Vitro.

    Science.gov (United States)

    Sun, Peng; Li, Jinan; Bu, Dengpan; Nan, Xuemei; Du, Hong

    2016-05-01

    This study was to investigate the effects of live or autoclaved Bacillus subtilis natto, their fermented products and media on rumen fermentation and rumen functional bacteria in vitro. Rumen fluid from three multiparous lactating Holstein cows was combined and transferred into serum bottles after diluted. Fifteen serum bottles were divided into five treatments, which were designed as following: CTR (the fermentation of 0.5 g TMR and ruminal fluids from dairy cows), LBS (CTR plus a minimum of 10(11) cfu live Bacillus subtilis natto), ABS (CTR plus a minimum of 10(11) cfu autoclaved Bacillus subtilis natto), BSC (CTR plus 1 ml Bacillus subtilis natto fermentation products without bacteria), and BSM (CTR plus 1 ml liquid fermentation medium). When separated from the culture, live Bacillus subtilis natto individually increased the concentrations of ammonia-N (P Bacillus subtilis natto has the similar function with the live bacteria except for the ratio of acetate and propionate. Except B. fibrisolvens, live or autoclaved Bacillus subtilis natto did not influence or decreased the 16S rRNA gene quantification of the detected bacteria. BSC and BSM altered the relative expression of certain functional bacteria in the rumen. These results indicated that it was Bacillus subtilis natto thalli that played the important role in promoting rumen fermentation when applied as a probiotic in dairy ration.

  5. Neural-networks-based feedback linearization versus model predictive control of continuous alcoholic fermentation process

    Energy Technology Data Exchange (ETDEWEB)

    Mjalli, F.S.; Al-Asheh, S. [Chemical Engineering Department, Qatar University, Doha (Qatar)

    2005-10-01

    In this work advanced nonlinear neural networks based control system design algorithms are adopted to control a mechanistic model for an ethanol fermentation process. The process model equations for such systems are highly nonlinear. A neural network strategy has been implemented in this work for capturing the dynamics of the mechanistic model for the fermentation process. The neural network achieved has been validated against the mechanistic model. Two neural network based nonlinear control strategies have also been adopted using the model identified. The performance of the feedback linearization technique was compared to neural network model predictive control in terms of stability and set point tracking capabilities. Under servo conditions, the feedback linearization algorithm gave comparable tracking and stability. The feedback linearization controller achieved the control target faster than the model predictive one but with vigorous and sudden controller moves. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  6. Continuous butyric acid fermentation coupled with REED technology for enhanced productivity

    DEFF Research Database (Denmark)

    Baroi, George Nabin; Skiadas, Ioannis; Westermann, Peter

    , today’s organic residues and wastes may become tomorrow’s platform for a variety of products for industrial use. Butyric acid fermentation has long been discussed in the last decade due to the wide application of butyric acid in chemical, pharmaceutical and food industries. Compared to other microbial......A major step towards the development of a sustainable industrial society is a shift from petroleum-based resources to renewable resources. An ongoing effort is focused on developing bio-refineries as an alternative way of producing fuels and chemical building-blocks from renewable resources. Thus...... strains, C.tyrobutyricum seems the most promising for biological production of butyric acid as it is characterised by higher selectivity and higher tolerance to butyric acid. However, studies on fermentative butyric production from lignocellulosic biomasses are scarce in the international literature...

  7. Effect of Single Bacterial Starter Culture on Odour Reduction During Controlled Fermentation of Cassava Tubers for Foofoo Production

    Directory of Open Access Journals (Sweden)

    Henshaw, E. E.

    2010-01-01

    Full Text Available Effects of single bacterial starter culture on odour reduction during controlled fermentation of cassava tubers for foofoo production were investigated. Pure cultures were used to ferment cassava tubers in water for 96 h. The cultures used include Bacillus subtilis, Klebsiela sp., Lactobacillus plantarum and Leuconostoc mesenteroides. L. plantarum exhibited the highest acid producing ability, decreasing the pH of the Cassava tubers from 6.2 to 3.68 with a corresponding increase in total titratable acidity (TTA from 0.082% to 0.290% during the 96 h fermentation period. The effected changes in pH and TTA by other organisms ranged respectively from 4.88 and 0.135% for Klebsiella sp., 4.68 and 0.136% for L. mesenteroides to 4.90 and 0.139% for B. subtilis with in the period. All the cultures were found to contribute in varying degree to odour reduction in fermented cassava; B. subtilis effected the highest odour reduction followed by L. plantarum.

  8. Factors Affecting Volatile Phenol Production During Fermentations with Pure and Mixed Cultures of Dekkera bruxellensis and Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Janez Kosel

    2014-01-01

    Full Text Available The paper examines the impact of ethanol, and hidroxycinnamic and vinylphenol precursors on the production of volatile phenols in fermentations of mixed and pure cultures of yeasts Saccharomyces cerevisiae and Dekkera bruxellensis. Three different D. bruxellensis strains were examined and they all showed a unique volatile phenol production pattern in the fermentations of pure and mixed cultures. Generally, the results showed that in mixed culture fermentations less vinylphenols and more ethylphenols were produced in comparison with D. bruxellensis pure culture fermentations. Vinylphenol precursors significantly inhibited the growth of S. cerevisiae and the production of ethylphenols. Nevertheless, it was found that D. bruxellensis genes encoding for enzymes coumaric acid decarboxylase (CAD and vinylphenol reductase (VPR are more responsive to vinylphenol precursors in comparison with hidroxycinnamic acids. Consequently, higher concentrations of vinylphenols in the cell were found to be more cytotoxic than hidroxycinnamic acids. In general, low ethanol concentrations induced higher production of volatile phenols by S. cerevisiae and D. bruxellensis. This was confirmed with the expression pattern of gene encoding for CAD of D. bruxellensis.

  9. Method for sustaining microorganism culture in syngas fermentation process in decreased concentration or absence of various substrates

    Science.gov (United States)

    Adams, Stephen S.; Scott, Syrona; Ko, Ching-Whan

    2015-05-19

    The present invention relates to methods for sustaining microorganism culture in a syngas fermentation reactor in decreased concentration or absence of various substrates comprising: adding carbon dioxide and optionally alcohol; maintaining free acetic acid concentrations; and performing the above mentioned steps within specified time.

  10. Cultural condition affecting the growth and production of beta-galactosidase by Bifidobacterium longum CCRC 15708 in a jar fermenter.

    Science.gov (United States)

    Hsu, C A; Yu, R C; Lee, S L; Chou, C C

    2007-05-01

    In the present study, the growth and production of beta-galactosidase by Bifidobacterium longum CCRC 15708 in a 5-L jar fermenter as influenced by cultivation temperature (27-42 degrees C), medium pH (4.5-7.5) and agitation speed (5-200 rpm) were evaluated. In general, it was found that a cultivation temperature of 37 degrees C proved optimal for both growth and beta-galactosidase production by the test organism. Although the growth of the test organism was the highest in the culture with pH controlled at 4.5-6.5, the culture with pH controlled at 6.5 resulted in the highest production of beta-galactosidase. Further, agitation at 100 rpm or more was found to enhance both the growth and production of beta-galactosidase. Fermentation conducted in a jar fermenter having the pH of the culture medium, the cultivation temperature, and the agitation speed controlled at 6.5, 37 degrees C, and 100 rpm, respectively, a maximum beta-galactosidase activity of 36.7 U/ml and a maximum transgalactosylation activity of 0.49 U/ml was achieved in 10 h of fermentation. There are ca 2.0 and 12.3 fold greater than the reported maximum beta-galactosidase and transgalactosylation activity, respectively, produced by B. longum CCRC 15708 in a flask culture system.

  11. Generation of flavour compounds in fermented sausages-the influence of curing ingredients, Staphylococcus starter culture and ripening time

    DEFF Research Database (Denmark)

    Olesen, Pelle Thonning; Meyer, Anne Boye Strunge; Stahnke, Louise Heller

    2004-01-01

    The volatile profiles of fermented sausages made with either Staphylococcus xylosus or Staphylococcus carnosus starter cultures were studied with regard to the influence of salt concentration, ripening time and three different combinations of curing ingredients-nitrate, nitrite or nitrite/ascorba...

  12. Lactobacillus sakei: A Starter for Sausage Fermentation, a Protective Culture for Meat Products

    Directory of Open Access Journals (Sweden)

    Monique Zagorec

    2017-09-01

    Full Text Available Among lactic acid bacteria of meat products, Lactobacillus sakei is certainly the most studied species due to its role in the fermentation of sausage and its prevalence during cold storage of raw meat products. Consequently, the physiology of this bacterium regarding functions involved in growth, survival, and metabolism during meat storage and processing are well known. This species exhibits a wide genomic diversity that can be observed when studying different strains and on which probably rely its multiple facets in meat products: starter, spoiler, or protective culture. The emerging exploration of the microbial ecology of meat products also revealed the multiplicity of bacterial interactions L. sakei has to face and their various consequences on microbial quality and safety at the end of storage.

  13. The effect of heat pretreatment temperature on fermentative hydrogen production using mixed cultures

    Energy Technology Data Exchange (ETDEWEB)

    Baghchehsaraee, Bita; Nakhla, George; Karamanev, Dimitre; Margaritis, Argyrios [Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, Ontario N6A 5B9 (Canada); Reid, Gregor [Department of Microbiology and Immunology, The University of Western Ontario, London, Ontario (Canada); Canadian Research and Development Center for Probiotics, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2 (Canada)

    2008-08-15

    The effect of heat treatment at different temperatures on two types of inocula, activated sludge and anaerobically digested sludge, was investigated in batch cultures. Heat treatments were conducted at 65, 80 and 95 C for 30 min. The untreated inocula produced less amount of hydrogen than the pretreated inocula, with lactic acid as the main metabolite. The maximum yields of 2.3 and 1.6 mol H{sub 2}/mol glucose were achieved for the 65 C pretreated anaerobically digested and activated sludges, respectively. Approximately a 15% decrease in yield was observed with increasing pretreatment temperature from 65 to 95 C concomitant with an increase in butyrate/acetate ratio from 1.5 to 2.4 for anaerobically digested sludge. The increase of pretreatment temperature of activated sludge to 95 C suppressed the hydrogen production by lactic acid fermentation. DNA analysis of the microbial community showed that the elevated pretreatment temperatures reduced the species diversity. (author)

  14. Culture condition improvement for whole-cell lipase production in submerged fermentation by Rhizopus chinensis using statistical method.

    Science.gov (United States)

    Teng, Yun; Xu, Yan

    2008-06-01

    Rhizopus chinensis CCTCC M201021 was a versatile strain capable of producing whole-cell lipase with synthetic activity in submerged fermentation. In order to improve the production of whole-cell lipase and study the culture conditions systematically, the combination of taguchi method and response surface methodology was performed. Taguchi method was used for the initial optimization, and eight factors viz., maltose, olive oil, peptone, K2HPO4, agitation, inoculum size, fermentation volume and pH were selected for this study. The whole-cell lipase activity yield was two times higher than the control experiment under initial optimal conditions, and four significant factors (inoculum, olive oil, fermentation volume and peptone) were selected to test the effect on the lipase production using response surface methodology. The optimal fermentation parameters for enhanced whole-cell lipase yield were found to be: inoculum 4.25 x 10(8) spores/L, olive oil 2.367% (w/v), fermentation volume 18 mL/250 mL flask, peptone 4.06% (w/v). Subsequent experimental trails confirmed the validity of the model. These optimal culture conditions in the shake flask led to a lipase yield of 13875 U/L, which 120% increased compare with the non-optimized conditions.

  15. Effect of hydrocolloid type on physiochemical properties of nonfat drinkable yogurt fermented with ropy and non-ropy yogurt cultures

    OpenAIRE

    Ahmed Saad Gad; Sahar Hassan Salah Mohamad

    2014-01-01

    Drinkable yogurt is defined as a dairy-based yogurt that is drinkable in a liquid form and may or may not include fruit or fruit flavoring. Mouthfeel defects may be affected by processing conditions, starter cultures and stabilizer selection. This research was investigated the effect of hydrocolloid type (gelatin, carboxymethylcellulose or high methoxy pectin) on the sensory characteristics and rheological properties of drinkable yogurts fermented with nonropy and ropy yogurt cultures. The re...

  16. Potential of starter culture to reduce biogenic amines accumulation in som-fug, a Thai traditional fermented fish sausage

    Directory of Open Access Journals (Sweden)

    Jirasak Kongkiattikajorn

    2015-12-01

    Full Text Available This study assessed the effects of starter cultures (Lactobacillus sakei KM5474 and Lactobacillus plantarum KM1450 on the accumulation of biogenic amines (BAs in Thai traditional fermented fish sausage. BAs formation (cadaverine, putrescine, histamine, tryptamine, phenylethylamine, and tyramine was significantly higher in som-fug fermentation without starter culture. Accumulation of these BAs in som-fug could reduce significantly by the incubation with of L. sakei KM5474 and L. plantarum KM1450. The influence of the availability of free amino acids (FAAs on BA formation during the fermentation of som-fug with and without starter culture was also investigated. The significant differences in the amount of some FAAs among batches would be partially attributed to the distinct proteolytic and BAs accumulation of specific microbiota of each batch. In general, amounts of FAA were related with their corresponding BAs. In batch control of the availability of practically all FAA precursors, BA formation could be observed. The formation of some BAs (histamine, putrescine, cadaverine, and phenylethylamine occurring in batch control was related to the amounts of FAA precursors (histidine, arginine, lysine, and phenylalanine. Starter culture L. plantarum KM1450 was more efficient in reducing BA accumulation in som-fug than that of starter culture L. sakei KM5474, while mixed starter cultures of L. sakei KM5474 and L. plantarum KM1450 showed the highest effectiveness in reducing BA accumulation during som-fug fermentation compared with the sample sausage without starter culture or with monostarter culture.

  17. Effect of organic loading rate on dark fermentative hydrogen production in the continuous stirred tank reactor and continuous mixed immobilized sludge reactor from waste pastry hydrolysate.

    Science.gov (United States)

    Han, Wei; Hu, Yunyi; Li, Shiyi; Nie, Qiulin; Zhao, Hongting; Tang, Junhong

    2016-12-01

    Waste pastry (6%, w/v) was hydrolyzed by the produced glucoamylase and protease to obtain the glucose (19.8g/L) and free amino nitrogen (179mg/L) solution. Then, the effect of organic loading rate (OLR) (8-40kgCOD/(m3d)) on dark fermentative hydrogen production in the continuous stirred tank reactor (CSTR) and continuous mixed immobilized sludge reactor (CMISR) from waste pastry hydrolysate was investigated and compared. The maximum hydrogen production rate of CSTR (277.76mL/(hL)) and CMISR (320.2mL/(hL)) were achieved at OLR of 24kgCOD/(m3d) and 32kgCOD/(m3d), respectively. Carbon recovery ranged from 75.2-84.1% in the CSTR and CMISR with the balance assumed to be converted to biomass. One gram waste pastry could produce 0.33g (1.83mmol) glucose which could be further converted to 79.24mL (3.54mmol) hydrogen in the CMISR or 91.66mL (4.09mmol) hydrogen in the CSTR. This is the first study which reports dark fermentative hydrogen production from waste pastry. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Application of starter cultures to table olive fermentation: an overview on the experimental studies

    OpenAIRE

    Aldo eCorsetti; Giorgia ePerpetuini; Maria eSchirone; Rosanna eTofalo; Giovanna eSuzzi

    2012-01-01

    Table olives are one of the oldest fermented foods and are considered as an important component of the Mediterranean diet, since their richness in monounsaturated fats (primarily oleic acid) and phenolic compounds may function as antioxidants in the human body; in the Western world they represent one of the most popular fermented vegetables but, despite its economic significance, table olive fermentation is still craft-based and empirical. In particular, such a type of fermentation results fr...

  19. Complex microbiota of a Chinese "Fen" liquor fermentation starter (Fen-Daqu), revealed by culture-dependent and culture-independent methods

    NARCIS (Netherlands)

    Zheng, X.; Zheng, Y.; Han, B.; Zwietering, M.H.; Samson, R.A.; Boekhout, T.; Nout, M.J.R.

    2012-01-01

    Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen-Daqu, a starter for light-flavour liquor, using combined culture-dependent and

  20. Complex microbiota of a Chinese "Fen" liquor fermentation starter (Fen-Daqu), revealed by culture-dependent and culture-independent methods

    NARCIS (Netherlands)

    Zheng, X.W.; Yan, Z.; Han, B.Z.; Zwietering, M.H.; Samson, R.A.; Boekhout, T.; Nout, M.J.R.

    2012-01-01

    Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen- Daqu, a starter for light-flavour liquor, using combined culture-dependent and

  1. The impact of oxygen on the final alcohol content of wine fermented by a mixed starter culture.

    Science.gov (United States)

    Morales, Pilar; Rojas, Virginia; Quirós, Manuel; Gonzalez, Ramon

    2015-05-01

    We have developed a wine fermentation procedure that takes advantage of the metabolic features of a previously characterized Metschnikowia pulcherrima strain in order to reduce ethanol production. It involves the use of M. pulcherrima/Saccharomyces cerevisiae mixed cultures, controlled oxygenation conditions during the first 48 h of fermentation, and anaerobic conditions thereafter. The influence of different oxygenation regimes and initial inoculum composition on yeast physiology and final ethanol content was studied. The impact of oxygenation on yeast physiology goes beyond the first aerated step and influences yields and survival rates during the anaerobic stage. The activity of M. pulcherrima in mixed oxygenated cultures resulted in a clear reduction in ethanol yield, as compared to S. cerevisiae. Despite relatively low initial cell numbers, S. cerevisiae always predominated in mixed cultures by the end of the fermentation process. Strain replacement was faster under low oxygenation levels. M. pulcherrima confers an additional advantage in terms of dissolved oxygen, which drops to zero after a few hours of culture, even under highly aerated conditions, and this holds true for mixed cultures. Alcohol reduction values about 3.7 % (v/v) were obtained for mixed cultures under high aeration, but they were associated to unacceptable volatile acidity levels. In contrast, under optimized conditions, only 0.35 g/L acetic acid was produced, for an alcohol reduction of 2.2 % (v/v), and almost null dissolved oxygen during the process.

  2. Transcriptional and Enzymatic Profiling of Pleurotus ostreatus Laccase Genes in Submerged and Solid-State Fermentation Cultures

    Science.gov (United States)

    Castanera, Raúl; Pérez, Gúmer; Omarini, Alejandra; Alfaro, Manuel; Pisabarro, Antonio G.; Faraco, Vincenza; Amore, Antonella

    2012-01-01

    The genome of the white rot basidiomycete Pleurotus ostreatus includes 12 phenol oxidase (laccase) genes. In this study, we examined their expression profiles in different fungal strains under different culture conditions (submerged and solid cultures) and in the presence of a wheat straw extract, which was used as an inducer of the laccase gene family. We used a reverse transcription-quantitative PCR (RT-qPCR)-based approach and focused on determining the reaction parameters (in particular, the reference gene set for the normalization and reaction efficiency determinations) used to achieve an accurate estimation of the relative gene expression values. The results suggested that (i) laccase gene transcription is upregulated in the induced submerged fermentation (iSmF) cultures but downregulated in the solid fermentation (SSF) cultures, (ii) the Lacc2 and Lacc10 genes are the main sources of laccase activity in the iSmF cultures upon induction with water-soluble wheat straw extracts, and (iii) an additional, as-yet-uncharacterized activity (Unk1) is specifically induced in SSF cultures that complements the activity of Lacc2 and Lacc10. Moreover, both the enzymatic laccase activities and the Lacc gene family transcription profiles greatly differ between closely related strains. These differences can be targeted for biotechnological breeding programs for enzyme production in submerged fermentation reactors. PMID:22467498

  3. The use of a starter culture in the fermentation of cassava for the production of "kivunde", a traditional Tanzanian food product.

    Science.gov (United States)

    Kimaryo, V M; Massawe, G A; Olasupo, N A; Holzapfel, W H

    2000-06-01

    Three cassava fermentation methods (spontaneous fermentation, back-slopping and the use of starter culture) for the production of kivunde, executed in three trials at 30 degrees C, were compared in terms of cyanide level reduction, microbiology and product quality improvement. Among the isolates from spontaneously fermented cassava batches, four strains were selected on the basis of their enzymatic activities and acid production. All were identified as Lactobacillus plantarum and were used as starters in this study. Lowest residual cyanide levels were detected after 120 h fermentation time in samples fermented with the starter culture and were below the maximum value of 10 mg/kg recommended by the Codex/FAO for cassava flour. This finding seems to be related to the alpha-glucosidase activity of the inoculated strains of which API-zyme (Bio-Merieux) tests showed activities of between 20 and > or = 40 nmol/4 h. The total residual cyanide levels of the spontaneous and back-slopping fermentations at 96 h were respectively 43.5 and 47.7 mg/kg dry weight of cassava. Extension of the fermentation period to 5 days, lead to further substantial reduction in the residual cyanide level in both these processes, but not below the recommended maximum value as in the case of starter culture fermented products. The spontaneous and back-slopping fermented cassava showed signs of deterioration after 3 days of fermentation. There was a sharp drop of pH and an increase of titratable acidity for all three batches during the first 48 h followed by a slow rise of pH and drop in titratable acidity towards the end of fermentation. The samples fermented with the starter culture had a smooth texture and pleasant fruity aroma, as opposed to the course and dull appearance and more complex flavour of the samples of spontaneous and back-slopping batches. During fermentation with starter culture, Enterobacteriaceae and yeasts and moulds could not be isolated throughout the period of fermentation

  4. Continuous hydrogen and methane production in a two-stage cheese whey fermentation system.

    Science.gov (United States)

    Cota-Navarro, C B; Carrillo-Reyes, J; Davila-Vazquez, G; Alatriste-Mondragón, F; Razo-Flores, E

    2011-01-01

    The feasibility of integrating biological hydrogen and methane production in a two-stage process using mixed cultures and cheese whey powder (CWP) as substrate was studied. The effect of operational parameters such as hydraulic retention time (HRT) and organic loading rate (OLR) on the volumetric hydrogen (VHPR) and methane (VMPR) production rates was assessed. The highest VHPR was 28 L H2/L/d, obtained during stable operation in a CSTR at HRT and OLR of 6 h and 142 g lactose/ L/d, respectively. Moreover, hydrogen (13 L/L/d) was produced even at HRT as low as 3.5 h and OLR of 163 g lactose/L/d, nonetheless, the reactor operation was not stable. Regarding methane production in an UASB reactor, the acidified effluent from the hydrogen-producing bioreactor was efficiently treated obtaining COD removals above 90% at OLR and HRT of 20 g COD/L/d and 6 h, respectively. The two-stage process for continuous production of hydrogen and methane recovered over 70% of the energy present in the substrate. This study demonstrated that hydrogen production can be efficiently coupled to methane production in a two-stage system and that CWP is an adequate substrate for energy production.

  5. Application' and validation of autochthonous lactic acid bacteria starter cultures for controlled leek fermentations and their influence on the antioxidant properties of leek.

    Science.gov (United States)

    Wouters, D; Bernaert, N; Anno, N; Van Droogenbroeck, B; De Loose, M; Van Bockstaele, E; De Vuyst, L

    2013-07-15

    Leek (Allium ampeloprasum var. porrum) is one of Belgium's most important outdoor vegetables, mainly cultivated for its white shaft. Fermentation of leek offers opportunities in view of biomass valorization and product diversification. This study deals with the implementation and validation of starter cultures to perform controlled leek fermentations and to ensure a high quality of the end-products. Therefore, a thorough study of the fermentation microbiology and the influence of three starter culture strains (Lactobacillus plantarum IMDO 788, Lactobacillus sakei IMDO 1358, and Leuconostoc mesenteroides IMDO 1347) on the metabolite kinetics of leek fermentation and antioxidant properties of leek was performed. Overall, the application of lactic acid bacteria starter cultures resulted in a fast prevalence of the species involved, coupled to an accelerated acidification. Of the three starter cultures tested, the mixed starter culture of L. plantarum IMDO 788 and L. mesenteroides IMDO 1347 was most promising, as its application resulted in fermented leek of good microbiological quality and in a more extensive carbohydrate consumption, whereby diverse end-metabolites were produced. However, high residual fructose concentrations allowed yeast outgrowth, resulting in increased ethanol and glycerol concentrations, and indicated the lack of a prevailing strictly heterofermentative LAB species. The antioxidant capacity of fermented leek samples, as measured with the oxygen radical absorbance capacity assay, increased when starter cultures were used, whereas with regard to 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, only leek fermented with L. sakei IMDO 1358 scored higher than spontaneously fermented leek. The total phenolic content was not influenced by the use of starter cultures, while the S-alk(en)yl-L-cysteine sulfoxides content decreased strongly. A preliminary sensory analysis revealed that the spontaneously fermented leek and the one obtained

  6. Mathematical modeling of continuous ethanol fermentation in a membrane bioreactor by pervaporation compared to conventional system: Genetic algorithm.

    Science.gov (United States)

    Esfahanian, Mehri; Shokuhi Rad, Ali; Khoshhal, Saeed; Najafpour, Ghasem; Asghari, Behnam

    2016-07-01

    In this paper, genetic algorithm was used to investigate mathematical modeling of ethanol fermentation in a continuous conventional bioreactor (CCBR) and a continuous membrane bioreactor (CMBR) by ethanol permselective polydimethylsiloxane (PDMS) membrane. A lab scale CMBR with medium glucose concentration of 100gL(-1) and Saccharomyces cerevisiae microorganism was designed and fabricated. At dilution rate of 0.14h(-1), maximum specific cell growth rate and productivity of 0.27h(-1) and 6.49gL(-1)h(-1) were respectively found in CMBR. However, at very high dilution rate, the performance of CMBR was quite similar to conventional fermentation on account of insufficient incubation time. In both systems, genetic algorithm modeling of cell growth, ethanol production and glucose concentration were conducted based on Monod and Moser kinetic models during each retention time at unsteady condition. The results showed that Moser kinetic model was more satisfactory and desirable than Monod model. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. A new process for the production of clinical dextran by mixed-culture fermentation of Lipomyces starkeyi and Leuconostoc mesenteroides.

    Science.gov (United States)

    Kim, D; Day, D F

    1994-10-01

    A mixed-culture fermentation system was designed for the production of size-limited dextrans. This process was simpler and more economical than traditional methods. It required the establishment of microbial consortia of Lipomyces starkeyi ATCC 74054 and Leuconostoc mesenteroides ATCC 10830. Controlling initial conditions, growth, and enzyme production by both organisms controlled the product size. In this process, both strains were grown separately and then mixed. Dextran fermentation was then allowed to proceed. At the desired time (and molecular size), the fermentation was harvested. The optimum pH and temperature for production of clinical dextran (75,000 MW) were 5.2 (+/- 0.1) and 28 (+/- 0.5) degrees C, respectively. Varying the ratio of L. mesenteroides to L. starkeyi in the inoculum did not significantly affect either the final cell ratios or dextran production.

  8. Evaluation of a functional soy product with addition of soy fiber and fermented with probiotic kefir culture

    Directory of Open Access Journals (Sweden)

    Tahis Regina Baú

    2014-06-01

    Full Text Available The objective of this study was to evaluate the chemical, sensory properties and stability of a functional soy product with soy fiber and fermented with probiotic kefir culture. The product was characterized by the chemical composition, color and sensory analysis. The stability of the product was evaluated by pH, acidity, viscosity, firmness, syneresis measurements and cells counts. The functional soy product presented better chemical composition and difference in color compared to the fermented product without fiber. Sensory analysis showed that the functional soy product had good acceptance and had better firmness and reduced syneresis compared to fermented product without fiber. The lactic acid bacteria counts decreased slightly during 28 days at 4°C of the storage and the product showed good microbiological stability. The functional soy product due to high Lactococcus lactis counts could be considered as a probiotic for the entire storage period.

  9. Hydrogen production from continuous flow, microbial reverse-electrodialysis electrolysis cells treating fermentation wastewater.

    Science.gov (United States)

    Watson, Valerie J; Hatzell, Marta; Logan, Bruce E

    2015-11-01

    A microbial reverse-electrodialysis electrolysis cell (MREC) was used to produce hydrogen gas from fermentation wastewater without the need for additional electrical energy. Increasing the number of cell pairs in the reverse electrodialysis stack from 5 to 10 doubled the maximum current produced from 60 A/m(3) to 120 A/m(3) using acetate. However, more rapid COD removal required a decrease in the anolyte hydraulic retention time (HRT) from 24 to 12 h to stabilize anode potentials. Hydrogen production using a fermentation wastewater (10 cell pairs, HRT=8 h) reached 0.9±0.1 L H2/Lreactor/d (1.1±0.1 L H2/g-COD), with 58±5% COD removal and a coulombic efficiency of 74±5%. These results demonstrated that consistent rates of hydrogen gas production could be achieved using an MREC if effluent anolyte COD concentrations are sufficient to produce stable anode potentials. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Feeding of Aspergillus oryzae fermentation culture (AOFC to growing sheep: 2. Growth rate and feed efficiency

    Directory of Open Access Journals (Sweden)

    D Lubis

    2002-12-01

    Full Text Available Utilization of yeast and or filamentous fungi as feed additive to ruminants has been of interest since the late 1980’s. Two fungi species have been commercially produced in the United States, (1 Yea-Sacc containing living cells of Saccharomyces cerevisiae and (2 Amaferm bearing Aspergillus oryzae fermentation extract. It has been demonstrated and proven that the cultures can enhance rumen development and function in young ruminants. This paper concerns the use of Aspergillus oryzae fermentation culture (AOFC as feed additive for young-growing male ‘Garut’ sheep. The A. oryzae was cultured in a media made of mineral-enriched ‘onggok’ flour, a material of tapioca processing waste. The AOFC was prepared gradually by incubating the fungus at room temperature (26 – 300C for 5 days, dried at 400C and ground. The AOFC was added to a commercial concentrate (GT-03 at 0, 5 and 10% (w/w levels, as treatment C0 (control, C1, and C2, respectively. Fifteen growing ‘Garut’ sheep were used and the concentrate feed treatments were randomly allotted based on a randomized block design. Drinking water was available at all time. The amount of feed offered (chopped King grass and concentrates and their refusals were weighed daily and live-weight of sheep was measured once a week in the morning. Daily feces was collected and weighed in the last 10 days of the 14-week experimental period. All feed and fecal samples were analyzed for dry matter, crude protein, total fiber (NDF, and ash. AOFC supplementation resulted in higher weight gains (P<0.05, which were 94.81; 122.08; and 140.52 g/d for C0, C1, and C2 treatments, respectively. Dry and organic matter, as well as protein intake was also significantly increased by inclusion of AOFC into concentrate diet (P<0.05. The increment in nutrient intake was from increased consumption of concentrates, and not from King grass, however, there was no effect of AOFC supplementation on feed efficiency.

  11. pH-induced gene regulation of solvent production by Clostridium acetobutylicum in continuous culture: parameter estimation and sporulation modelling.

    Science.gov (United States)

    Thorn, Graeme J; King, John R; Jabbari, Sara

    2013-02-01

    The acetone-butanol (AB) fermentation process in the anaerobic endospore-forming Gram-positive bacterium Clostridium acetobutylicum is useful as a producer of biofuels, particularly butanol. Recent work has concentrated on trying to improve the efficiency of the fermentation method, either through changes in the environmental conditions or by modifying the genome to selectively favour the production of one particular solvent over others. Fermentation of glucose by C. acetobutylicum occurs in two stages: initially the acids acetate and butyrate are produced and excreted and then, as the external pH falls, acetate and butyrate are ingested and further metabolised into the solvents acetone, butanol and ethanol. In order to optimise butanol production, it is important to understand how pH affects the enzyme-controlled reactions in the metabolism process. We adapt an ordinary differential equation model of the metabolic network with regulation at the genetic level for the required enzymes; parametrising the model using experimental data generated from continuous culture, we improve on previous point predictions (S. Haus, S. Jabbari, T. Millat, H. Janssen, R.-J. Fisher, H. Bahl, J. R. King, O. Wolkenhauer, A systems biology approach to investigate the effect of pH-induced gene regulation on solvent production by Clostridium acetobutylicum in continuous culture, BMC Systems Biology 5 (2011)) [1] both by using a different optimisation approach and by computing confidence intervals and correlation coefficients. We find in particular that the parameters are ill-determined from the data and that two separate clusters of parameters appear correlated, reflecting the importance of two metabolic intermediates. We extend the model further to include another aspect of the clostridial survival mechanism, sporulation, and by computation of the Akaike Information Criterion values find that the there is some evidence for the presence of sporulation during the shift. Copyright © 2012

  12. Obtaining fermented dairy products with the yogurt culture YF-L 812

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    INA VASILEAN

    2011-07-01

    Full Text Available Exopolysaccharides (EPS produced by some lactic acid bacteria cultures can efficiently replace commercial stabilizers for preventing or reducing syneresis, providing fermented milk products with suitable structure viscosity. The effect of EPS on food quality characteristics depends on the EPS properties themselves, as well as their interaction with various components of the food system. This paper was aimed at studying the influence of the environment composition on the EPS biosynthesis by starter culture YF-L 812 and at determining the properties of at yogurt obtained. High fat content of milk (3.5% and 1.5% had a positive effect on yogurt texture. In order to reduce the syneresis phenomenon, the milk with low fat content (0.1% was supplemented with different concentrations of milk powder and lactose. Our results indicated that the whey separated was reduced to 0.6% and 0.3% when the milk was supplemented with 2% lactose and 2% skimmed milk powder, and respectively, 3% lactose and 3% skimmed milk powder.

  13. Lean management systems: creating a culture of continuous quality improvement.

    Science.gov (United States)

    Clark, David M; Silvester, Kate; Knowles, Simon

    2013-08-01

    This is the first in a series of articles describing the application of Lean management systems to Laboratory Medicine. Lean is the term used to describe a principle-based continuous quality improvement (CQI) management system based on the Toyota production system (TPS) that has been evolving for over 70 years. Its origins go back much further and are heavily influenced by the work of W Edwards Deming and the scientific method that forms the basis of most quality management systems. Lean has two fundamental elements--a systematic approach to process improvement by removing waste in order to maximise value for the end-user of the service and a commitment to respect, challenge and develop the people who work within the service to create a culture of continuous improvement. Lean principles have been applied to a growing number of Healthcare systems throughout the world to improve the quality and cost-effectiveness of services for patients and a number of laboratories from all the pathology disciplines have used Lean to shorten turnaround times, improve quality (reduce errors) and improve productivity. Increasingly, models used to plan and implement large scale change in healthcare systems, including the National Health Service (NHS) change model, have evidence-based improvement methodologies (such as Lean CQI) as a core component. Consequently, a working knowledge of improvement methodology will be a core skill for Pathologists involved in leadership and management.

  14. Effect of light-dark cycles on hydrogen and poly-β-hydroxybutyrate production by a photoheterotrophic culture and Rhodobacter capsulatus using a dark fermentation effluent as substrate.

    Science.gov (United States)

    Montiel Corona, Virginia; Le Borgne, Sylvie; Revah, Sergio; Morales, Marcia

    2017-02-01

    A Rhodobacter capsulatus strain and a photoheterotrophic culture (IZT) were cultivated to produce hydrogen under different light-dark cycles. A dark fermentation effluent (DFE) was used as substrate. It was found that IZT culture had an average cumulative hydrogen production (Paccum H2) of 1300±43mLH2L-1 under continuous illumination and light-dark cycles of 30 or 60min. In contrast, R. capsulatus reduced its Paccum H2 by 20% under 30:30min light-dark cycles, but tripled its poly-β-hydroxybutyrate (PHB) content (308±2mgPHB gdw-1) compared to continuous illumination. The highest PHB content by IZT culture was 178±10mgPHB gdw-1 under 15:15min light-dark cycles. PCR-DGGE analysis revealed that the IZT culture was mainly composed of Rhodopseudomonas palustris identified with high nucleotide similarity (99%). The evaluated cultures might be used for hydrogen and PHB production. They might provide energy savings by using light-dark cycles and DFE valorization. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. New potentially antihypertensive peptides liberated in milk during fermentation with selected lactic acid bacteria and kombucha cultures.

    Science.gov (United States)

    Elkhtab, Ebrahim; El-Alfy, Mohamed; Shenana, Mohamed; Mohamed, Abdelaty; Yousef, Ahmed E

    2017-12-01

    Compounds with the ability to inhibit angiotensin-converting enzyme (ACE) are used medically to treat human hypertension. The presence of such compounds naturally in food is potentially useful for treating the disease state. The goal of this study was to screen lactic acid bacteria, including species commonly used as dairy starter cultures, for the ability to produce new potent ACE-inhibiting peptides during milk fermentation. Strains of Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus helveticus, Lactobacillus paracasei, Lactococcus lactis, Leuconostoc mesenteroides, and Pediococcus acidilactici were tested in this study. Additionally, a symbiotic consortium of yeast and bacteria, used commercially to produce kombucha tea, was tested. Commercially sterile milk was inoculated with lactic acid bacteria strains and kombucha culture and incubated at 37°C for up to 72 h, and the liberation of ACE-inhibiting compounds during fermentation was monitored. Fermented milk was centrifuged and the supernatant (crude extract) was subjected to ultrafiltration using 3- and 10-kDa cut-off filters. Crude and ultrafiltered extracts were tested for ACE-inhibitory activity. The 10-kDa filtrate resulting from L. casei ATCC 7469 and kombucha culture fermentations (72 h) showed the highest ACE-inhibitory activity. Two-step purification of these filtrates was done using HPLC equipped with a reverse-phase column. Analysis of HPLC-purified fractions by liquid chromatography-mass spectrometry/mass spectrometry identified several new peptides with potent ACE-inhibitory activities. Some of these peptides were synthesized, and their ACE-inhibitory activities were confirmed. Use of organisms producing these unique peptides in food fermentations could contribute positively to human health. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  16. Simultaneous Saccharification and Fermentation of Sugar Beet Pulp with Mixed Bacterial Cultures for Lactic Acid and Propylene Glycol Production

    Directory of Open Access Journals (Sweden)

    Joanna Berlowska

    2016-10-01

    Full Text Available Research into fermentative production of lactic acid from agricultural by-products has recently concentrated on the direct conversion of biomass, whereby pure sugars are replaced with inexpensive feedstock in the process of lactic acid production. In our studies, for the first time, the source of carbon used is sugar beet pulp, generated as a by-product of industrial sugar production. In this paper, we focus on the simultaneous saccharification of lignocellulosic biomass and fermentation of lactic acid, using mixed cultures with complementary assimilation profiles. Lactic acid is one of the primary platform chemicals, and can be used to synthesize a wide variety of useful products, including green propylene glycol. A series of controlled batch fermentations was conducted under various conditions, including pretreatment with enzymatic hydrolysis. Inoculation was performed in two sequential stages, to avoid carbon catabolite repression. Biologically-synthesized lactic acid was catalytically reduced to propylene glycol over 5% Ru/C. The highest lactic acid yield was obtained with mixed cultures. The yield of propylene glycol from the biological lactic acid was similar to that obtained with a water solution of pure lactic acid. Our results show that simultaneous saccharification and fermentation enables generation of lactic acid, suitable for further chemical transformations, from agricultural residues.

  17. Simultaneous Saccharification and Fermentation of Sugar Beet Pulp with Mixed Bacterial Cultures for Lactic Acid and Propylene Glycol Production.

    Science.gov (United States)

    Berlowska, Joanna; Cieciura, Weronika; Borowski, Sebastian; Dudkiewicz, Marta; Binczarski, Michal; Witonska, Izabela; Otlewska, Anna; Kregiel, Dorota

    2016-10-17

    Research into fermentative production of lactic acid from agricultural by-products has recently concentrated on the direct conversion of biomass, whereby pure sugars are replaced with inexpensive feedstock in the process of lactic acid production. In our studies, for the first time, the source of carbon used is sugar beet pulp, generated as a by-product of industrial sugar production. In this paper, we focus on the simultaneous saccharification of lignocellulosic biomass and fermentation of lactic acid, using mixed cultures with complementary assimilation profiles. Lactic acid is one of the primary platform chemicals, and can be used to synthesize a wide variety of useful products, including green propylene glycol. A series of controlled batch fermentations was conducted under various conditions, including pretreatment with enzymatic hydrolysis. Inoculation was performed in two sequential stages, to avoid carbon catabolite repression. Biologically-synthesized lactic acid was catalytically reduced to propylene glycol over 5% Ru/C. The highest lactic acid yield was obtained with mixed cultures. The yield of propylene glycol from the biological lactic acid was similar to that obtained with a water solution of pure lactic acid. Our results show that simultaneous saccharification and fermentation enables generation of lactic acid, suitable for further chemical transformations, from agricultural residues.

  18. Nondairy beverage produced by controlled fermentation with potential probiotic starter cultures of lactic acid bacteria and yeast.

    Science.gov (United States)

    Freire, Ana Luiza; Ramos, Cintia Lacerda; da Costa Souza, Patrícia Nirlane; Cardoso, Mauro Guilherme Barros; Schwan, Rosane Freitas

    2017-05-02

    This work aimed to develop a nondairy fermented beverage from a blend of cassava and rice based on Brazilian indigenous beverage cauim using probiotic lactic acid bacteria (LAB) and yeast. The indigenous strains Lactobacillus plantarum CCMA 0743 (from cauim) and Torulaspora delbrueckii CCMA 0235 (from tarubá), and the commercial probiotic, L. acidophilus LAC-04, were used as starter cultures in single and co-cultivations. The bacteria populations were around 8.0 log (CFU/mL) at the end of all fermentations as recommended for probiotic products. Higher residual starch contents were noted in the single LAB cultures (10.6% [w/w]) than in co-cultures (lactic acid was the main organic acid detected (>1.6g/L) and ethanol was lower than 0.5% (w/v) consisting in a non-alcoholic beverage. The assays containing yeast showed the highest antioxidant activity (around 10% by DPPH and ABTS methods). Therefore, a nondairy fermented beverage was successfully obtained, and the co-culture of LAB and T. delbrueckii could increase the product's functional properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. New method for selection of hydrogen peroxide adapted bifidobacteria cells using continuous culture and immobilized cell technology

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    Meile Leo

    2010-07-01

    Full Text Available Abstract Background Oxidative stress can severely compromise viability of bifidobacteria. Exposure of Bifidobacterium cells to oxygen causes accumulation of reactive oxygen species, mainly hydrogen peroxide, leading to cell death. In this study, we tested the suitability of continuous culture under increasing selective pressure combined with immobilized cell technology for the selection of hydrogen peroxide adapted Bifidobacterium cells. Cells of B. longum NCC2705 were immobilized in gellan-xanthan gum gel beads and used to continuously ferment MRS medium containing increasing concentration of H2O2 from 0 to 130 ppm. Results At the beginning of the culture, high cell density of 1013 CFU per litre of reactor was tested. The continuous culture gradually adapted to increasing H2O2 concentrations. However, after increasing the H2O2 concentration to 130 ppm the OD of the culture decreased to 0. Full wash out was prevented by the immobilization of the cells in gel matrix. Hence after stopping the stress, it was possible to re-grow the cells that survived the highest lethal dose of H2O2 and to select two adapted colonies (HPR1 and HPR2 after plating of the culture effluent. In contrast to HPR1, HPR2 showed stable characteristics over at least 70 generations and exhibited also higher tolerance to O2 than non adapted wild type cells. Preliminary characterization of HPR2 was carried out by global genome expression profile analysis. Two genes coding for a protein with unknown function and possessing trans-membrane domains and an ABC-type transporter protein were overexpressed in HPR2 cells compared to wild type cells. Conclusions Our study showed that continuous culture with cell immobilization is a valid approach for selecting cells adapted to hydrogen peroxide. Elucidation of H2O2 adaptation mechanisms in HPR2 could be helpful to develop oxygen resistant bifidobacteria.

  20. New method for selection of hydrogen peroxide adapted bifidobacteria cells using continuous culture and immobilized cell technology.

    Science.gov (United States)

    Mozzetti, Valeria; Grattepanche, Franck; Moine, Déborah; Berger, Bernard; Rezzonico, Enea; Meile, Leo; Arigoni, Fabrizio; Lacroix, Christophe

    2010-07-27

    Oxidative stress can severely compromise viability of bifidobacteria. Exposure of Bifidobacterium cells to oxygen causes accumulation of reactive oxygen species, mainly hydrogen peroxide, leading to cell death. In this study, we tested the suitability of continuous culture under increasing selective pressure combined with immobilized cell technology for the selection of hydrogen peroxide adapted Bifidobacterium cells. Cells of B. longum NCC2705 were immobilized in gellan-xanthan gum gel beads and used to continuously ferment MRS medium containing increasing concentration of H2O2 from 0 to 130 ppm. At the beginning of the culture, high cell density of 10(13) CFU per litre of reactor was tested. The continuous culture gradually adapted to increasing H2O2 concentrations. However, after increasing the H2O2 concentration to 130 ppm the OD of the culture decreased to 0. Full wash out was prevented by the immobilization of the cells in gel matrix. Hence after stopping the stress, it was possible to re-grow the cells that survived the highest lethal dose of H2O2 and to select two adapted colonies (HPR1 and HPR2) after plating of the culture effluent. In contrast to HPR1, HPR2 showed stable characteristics over at least 70 generations and exhibited also higher tolerance to O2 than non adapted wild type cells. Preliminary characterization of HPR2 was carried out by global genome expression profile analysis. Two genes coding for a protein with unknown function and possessing trans-membrane domains and an ABC-type transporter protein were overexpressed in HPR2 cells compared to wild type cells. Our study showed that continuous culture with cell immobilization is a valid approach for selecting cells adapted to hydrogen peroxide. Elucidation of H2O2 adaptation mechanisms in HPR2 could be helpful to develop oxygen resistant bifidobacteria.

  1. The availability of a lactose medium for tea fungus culture and Kombucha fermentation

    OpenAIRE

    Markov S.L.; Cvetković D.D.; Velićanski Aleksandra S.

    2012-01-01

    Kombucha is a traditional beverage that is prepared by fermenting sucrose-sweetened black tea. A medium is inoculated with a cellulose pellicle (popularly known as a “tea fungus”) or fermentation brought from previous cultivation process. Our aim was to test the possibility of obtaining a Kombucha beverage using different concentration of lactose as an alternative source of C-atoms. A traditional medium sweetened with sucrose or without sugar was used as control. Without lactose-ferment...

  2. Continuous alcoholic fermentation of glucose/xylose mixtures by co-immobilized Saccharomyces cerevisiae and Candida shehatae.

    Science.gov (United States)

    Lebeau, T; Jouenne, T; Junter, G A

    1998-09-01

    Viable Saccharomyces cerevisiae and Candida shehatae cells were co-immobilized in a composite agar layer/microporous membrane structure. This immobilized-cell structure was placed in a vertical position between the two halves of a double-chambered, stainless-steel bioreactor of original design and applied to the continuous alcoholic fermentation of a mixture of glucose (35 g dm-3) and xylose (15 g dm-3). Various dilution rates and initial cell loadings of the gel layer were tested. Simultaneous consumption of the two sugars was always observed. The best fermentation performance was obtained at low dilution rate (0.02 h-1) with an excess of C. shehatae over S. cerevisiae in the initial cell loading of the gel (5.0 mg dry weight and 0.65 mg dry weight cm-3 gel respectively): 100% of glucose and 73% of xylose were consumed with an ethanol yield coefficient of 0.48 g g total sugars-1. In these conditions, however, the ethanol production rate per unit volume of gel remained low (0.37 g h-1 dm-3). Viable cell counts in gel samples after incubation highlighted significant heterogeneities in the spatial distribution of the two yeast species in both the vertical and the transverse directions. In particular, the overall cell number decreased from the bottom to the top of the agar sheet, which may explain the low ethanol productivity relative to the total gel volume.

  3. Effects of pH and ORP on microbial ecology and kinetics for hydrogen production in continuously dark fermentation.

    Science.gov (United States)

    Song, Jiaxiu; An, Dong; Ren, Nanqi; Zhang, Yongming; Chen, Ying

    2011-12-01

    The microbial structure and kinetic characteristics of the hydrogen producing strains in two fermentative continuous stirred-tank reactors (CSTRs) were studied by controlling pH and oxidation and reduction potential (ORP). The fluorescence in situ hybridization (FISH) tests were conducted to investigate the fermentative performance of Clostridium histolyticum (C. histolyticum), Clostridium lituseburense (C. lituseburense) and Enterobacteriaceae. The experimental results showed that in ethanol-type reactor 1#, the relative abundance of the strains was 48%, 30% and 22%. Comparatively, the relative abundance in butyric acid-type reactor 2# was 24%, 55% and 19% with butyric acids and hydrogen as the main products. The kinetic results indicated that the hydrogen yield coefficients YP/X in both reactors were 8.357 and 5.951 l-H2/g, while the coefficients of the cellular yield were 0.0268 and 0.0350 g-Cell/g, respectively. At the same biomass, the hydrogen yield in ethanol-type reactors was more than that in butyric acid reactors. However, the cellular synthesis rate in ethanol-type reactors was low when the same carbon source was used. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Volatile Organic Compounds in Naturally Fermented Milk and Milk Fermented Using Yeasts, Lactic Acid Bacteria and Their Combinations As Starter Cultures

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    Bennie C. Viljoen

    2007-01-01

    Full Text Available The volatile organic compounds present in 18 Zimbabwean naturally fermented milk (amasi samples and those produced by various yeasts, lactic acid bacteria (LAB and yeast/ LAB combinations were determined using headspace gas chromatography. The yeast strains used were: Candida kefyr 23, C. lipolytica 57, Saccharomyces cerevisiae 71, C. lusitaniae 68, C. tropicalis 78, C. lusitaniae 63, C. colliculosa 41, S. dairenensis 32, and Dekkera bruxellensis 43, and were coded Y1 to Y9, respectively. The LAB strains used were Lactococcus lactis subsp. lactis Lc39, L. lactis subsp. lactis Lc261, Lactobacillus paracasei Lb11, and L. lactis subsp. lactis biovar. diacetylactis C1, and were coded B1 to B4, respectively. Some of the volatile organic compounds found in amasi were acetaldehyde, ethanol, acetone, 2-methyl propanal, 2-methyl-1-propanol and 3-methyl-1-butanol. However, the levels of volatile organic compounds in the naturally fermented milk (NFM samples varied from one sample to another, with acetaldehyde ranging from 0.1–18.4 ppm, 3-methyl butanal from <0.1–0.47 ppm and ethanol from 39.3–656 ppm. The LAB/C. kefyr 23 (B/Y1 co-cultures produced significantly (p<0.05 higher levels of acetaldehyde and ethanol than the levels found in the NFM. The acetaldehyde levels in the B/Y1 samples ranged from 26.7–87.7 ppm, with L. lactis subsp. lactis biovar. diacetylactis C1 (B4 producing the highest level of acetaldehyde in combination with C. kefyr 23 (Y1. Using principal component analysis (PCA, most of the NFM samples were grouped together with single and co-cultures of Lc261, Lb11 and the non-lactose fermenting yeasts, mainly because of the low levels of ethanol and similar levels of 3-methyl butanal. Chromatograms of amasi showed prominent peak of methyl aldehydes and their alcohols including 3-methyl-butanal and 3-methyl-butanol, suggesting that these compounds are important attributes of Zimbabwean naturally fermented milk.

  5. Combination of culture-independent and culture-dependent molecular methods for the determination of bacterial community of iru, a fermented Parkia biglobosa seeds.

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    Gbenga Adedeji Adewumi

    2013-01-01

    Full Text Available In this study, bacterial composition of iru produced by natural, uncontrolled fermentation of Parkia biglobosa seeds was assessed using culture-independent method in combination with culture-based genotypic typing techniques. PCR-denaturing gradient gel electrophoresis (DGGE revealed similarity in DNA fragments with the two DNA extraction methods used and confirmed bacterial diversity in the sixteen iru samples from different production regions. DNA sequencing of the highly variable V3 region of the 16S rRNA genes obtained from PCR-DGGE identified species related to Bacillus subtilis as consistent bacterial species in the fermented samples, while other major bands were identified as close relatives of Staphylococcus vitulinus, Morganella morganii, B. thuringiensis, Staphylococcus saprophyticus, Tetragenococcus halophilus, Ureibacillus thermosphaericus, Brevibacillus parabrevis, Salinicoccus jeotgali, Brevibacterium sp. and Uncultured bacteria clones. Bacillus species were cultured as potential starter cultures and clonal relationship of different isolates determined using amplified ribosomal DNA restriction analysis (ARDRA combined with 16S-23S rRNA gene internal transcribed spacer (ITS PCR amplification, restriction analysis (ITS-PCR-RFLP and randomly amplified polymorphic DNA (RAPD-PCR. This further discriminated Bacillus subtilis and its variants from food-borne pathogens such as Bacillus cereus and suggested the need for development of controlled fermentation processes and good manufacturing practices (GMP for iru production to achieve product consistency, safety quality and improved shelf life.

  6. Culture-independent bacterial community analysis of the salty-fermented fish paste products of Thailand and Laos

    OpenAIRE

    MARUI, Junichiro; BOULOM, Sayvisene; PANTHAVEE, Wanchai; MOMMA, Mari; KUSUMOTO, Ken-Ichi; NAKAHARA, Kazuhiko; SAITO, Masayoshi

    2015-01-01

    A bacterial community analysis, using a culture-independent method (polymerase chain reaction-denaturing gradient gel electrophoresis), detected 17 species of bacteria including species of the genera Tetragenococcus, Lactobacillus, Pediococcus, Weissella Halanaerobium, Clostridium, and Sphingomonas in a traditional salty-fermented fish paste known as pla-ra or pa-daek in Thailand and Laos, which is used as a storage-stable multi-purpose seasoning. The representative genus of lactic acid bacte...

  7. The influence of douchi starter cultures on the composition of extractive components, microbiological activity, and sensory properties of fermented fish pastes.

    Science.gov (United States)

    Kasankala, Ladislaus M; Xiong, Youling L; Chen, Jie

    2011-01-01

    Three experiments were conducted to test the hypothesis that douchi cultures could serve as a potential starter for enhancing the quality attributes of fermented silver carp meat. In experiment 1, an active, prefermented douchi culture was incorporated into a fish paste to aid in the fish fermentation (30 d) and facilitate biochemical production of extractive flavor components (PRF). In experiment 2, a fully fermented (30 d) douchi was added to a fish paste and the mixture was fermented for 30 d (PSF). In experiment 3, a fish paste without the douchi culture was fermented for 30 d (CF). Total extracted free amino acids increased by 68.0, 68.6, and 78.8% (P 100 mg/mL). The concentrations of both formaldehyde-reactive nitrogen and ammonia nitrogen extractives increased significantly (P PSF > CF. Low amounts of biogenic amines (ingredient commonly used in China, Japan, and other Asian countries. It is also used in many Chinese cuisines in the United States. On the other hand, fermented seafood made from freshwater fish such as silver carp is known to contain bioactive components believed to promote health. The findings from the present study indicated that douchi as a novel starter can be used to produce fermented silver carp fish pastes with excellent flavor and consumer acceptability. The results may be applicable to other fish species to produce similar fermentation products.

  8. Use of mixed culture bacteria for photofermentive hydrogen of dark fermentation effluent.

    Science.gov (United States)

    Tawfik, Ahmed; El-Bery, Haitham; Kumari, Sheena; Bux, Faizal

    2014-09-01

    Hydrogen production (HP) from dark fermentation effluent of starch wastewater via vertical tubular photo-bioreactor was investigated. The reactor was inoculated with mixed culture of bacteria and operated at light intensity of 190 W/m(2). Hydraulic retention time (HRT) and organic loading rate (OLR) was varied between 0.9 to 4.0 h and 3.2 to 16 g COD/l.d., respectively. Increasing the HRT from 0.9 to 2.5 h, significantly (P<0.05) increased HP from 1±0.04 to 3.05±0.19 l/d, respectively. However, minimal increase in HP occurred when increasing the HRT up to 4.0 h. The HP remained unaffected when increasing the OLR from 3.2 to 6.4 g COD/l.d. Further increase in the OLR up to 8.2 and 16 g COD/l.d., resulted in a drop in HP i.e. 0.96 and 0.19 l/d, respectively. Microbial community analysis of the reactor samples showed the presence and dominance of hydrogen producing purple non-sulfur phototrophic (PNS) bacterium, Rhodopseudomonas palustris in the reactor. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Elaboration of fermented dairy beverages: acceptability and viability of probiotic cultures

    Directory of Open Access Journals (Sweden)

    Adriana Carla Santos de Menezes Ramos

    2013-12-01

    Full Text Available This work aims to develop formulations of fermented dairy beverages with probiotic cultures (Lactobacillus acidophilus, Streptococcus thermophilus e Bifidobacterium bifidum yellow monbin flavored, to characterize the chemical composition and to evaluate the stability during refrigerated storage for 28 days.The dairy beverages were developed from an experimental design 3x3, with two factors and three levels each: yellow monbin pulp (15, 20 and 25% and whey (20, 30 and 40%. Nine formulations were produced and submitted to a sensory acceptability test. Thereafter three selected formulations were evaluated based on their microbiological characteristics, proximate composition, pH and titratable acidity. As the acceptance was higher than 70% in all the formulations, were selected that had a higher proportion of whey. Thus, the formulations F3, F6 e F9 were selected. Considering the proximate composition, the selected formulations not differed regarding for carbohydrates. The dairy beverages showed stability with respect to pH and acidity during the shelf life of 28 days and satisfactory results as the investigation of pathogenic microorganisms within the standards established. Quantification of lactic acid bacteria evidenced high numbers to Lactobacillus acidophilus and Streptococcus thermophilus, values between 11.6 to 10.2 CFU log/mL and 8.9 to 11 CFU log/mL, respectively. The species Bifidobacterium bifidum presented less than 6 log/ mL CFU for the formulations. Based on these results, the selected dairy beverages formulations had nutrition, technology and sensorial feasibility.

  10. Aspergillus oryzae S2 alpha-amylase production under solid state fermentation: optimization of culture conditions.

    Science.gov (United States)

    Sahnoun, Mouna; Kriaa, Mouna; Elgharbi, Fatma; Ayadi, Dorra-Zouari; Bejar, Samir; Kammoun, Radhouane

    2015-04-01

    Aspergillus oryzae S2 was assayed for alpha-amylase production under solid state fermentation (SSF). In addition to AmyA and AmyB already produced in monitored submerged culture, the strain was noted to produce new AmyB oligomeric forms, in particular a dominant tetrameric form named AmyC. The latter was purified to homogeneity through fractional acetone precipitation and size exclusion chromatography. SDS-PAGE and native PAGE analyses revealed that, purified AmyC was an approximately 172 kDa tetramer of four 42 kDa subunits. AmyC was also noted to display the same NH2-terminal amino acid sequence residues and approximately the same physico-chemical properties of AmyA and AmyB, to exhibit maximum activity at pH 5.6 and 60 °C, and to produce maltose and maltotriose as major starch hydrolysis end-products. Soyabean meal was the best substitute to yeast extract compared to fish powder waste and wheat gluten waste. AmyC production was optimized under SSF using statistical design methodology. Moisture content of 76.25%, C/N substrate ratio of 0.62, and inoculum size of 10(6.87) spores allowed maximum activity of 22118.34 U/g of dried substrate, which was 33 times higher than the one obtained before the application of the central composite design (CCD). Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Study of flocculent yeast performance in tower reactors for bioethanol production in a continuous fermentation process with no cell recycling.

    Science.gov (United States)

    Andrietta, Sílvio Roberto; Steckelberg, Cláudia; Andrietta, Maria da Graça Stupiello

    2008-05-01

    The purpose of this study was to assess the retention ability of 12 different Saccharomyces sp. yeast strains with flocculent characteristics when inoculated in a continuous ethanol fermentation process. The system was comprised of two reactors connected in series with no cell recycling. The feeding substrate used was a synthetic medium containing glucose. The parameters assessed were total reducing sugars of the feeding substrate, total reducing sugars and ethanol at the outlet of the first and second reactors and quantification and classification of yeast population in the two reactors. The system reached yield levels of 83.53% of theoretical yield with a maximum total reducing sugars conversion of 92.68%. The conversion in this system was lower than expected. The dominant yeast in the process in both reactors, contrary to expectation, was the Saccharomyces CP6 strain which was unable to form pellets in spite of its flocculate growth.

  12. Yeast diversity during the fermentation of Andean chicha: A comparison of high-throughput sequencing and culture-dependent approaches.

    Science.gov (United States)

    Mendoza, Lucía M; Neef, Alexander; Vignolo, Graciela; Belloch, Carmela

    2017-10-01

    Diversity and dynamics of yeasts associated with the fermentation of Argentinian maize-based beverage chicha was investigated. Samples taken at different stages from two chicha productions were analyzed by culture-dependent and culture-independent methods. Five hundred and ninety six yeasts were isolated by classical microbiological methods and 16 species identified by RFLPs and sequencing of D1/D2 26S rRNA gene. Genetic typing of isolates from the dominant species, Saccharomyces cerevisiae, by PCR of delta elements revealed up to 42 different patterns. High-throughput sequencing (HTS) of D1/D2 26S rRNA gene amplicons from chicha samples detected more than one hundred yeast species and almost fifty filamentous fungi taxa. Analysis of the data revealed that yeasts dominated the fermentation, although, a significant percentage of filamentous fungi appeared in the first step of the process. Statistical analysis of results showed that very few taxa were represented by more than 1% of the reads per sample at any step of the process. S. cerevisiae represented more than 90% of the reads in the fermentative samples. Other yeast species dominated the pre-fermentative steps and abounded in fermented samples when S. cerevisiae was in percentages below 90%. Most yeasts species detected by pyrosequencing were not recovered by cultivation. In contrast, the cultivation-based methodology detected very few yeast taxa, and most of them corresponded with very few reads in the pyrosequencing analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Fermentation Characteristics and Aromatic Profile of Plum Wines Produced with Indigenous Microbiota and Pure Cultures of Selected Yeast.

    Science.gov (United States)

    Miljić, Uroš; Puškaš, Vladimir; Vučurović, Vesna; Muzalevski, Ana

    2017-06-01

    The aim of this study was to assess and compare fermentation characteristics and aromatic profile of plum wines produced with indigenous microbiota and pure cultures of different selected yeast. Experiments were carried out with plum (Prunus domestica L.) varieties of different fruit ripening times (Čačanska rana, Čačanska lepotica, and Požegača). Wine fermentations were conducted by the activity of indigenous microbiota, commercially available Saccharomyces cerevisiae and Saccharomyces bayanus yeast strains and joint activity of Schizosaccharomyces pombe and S. cerevisiae (sequential inoculation). Statistically significant differences in fermentative characteristics and the content of certain volatile compounds were observed as a result of metabolic activity of various indigenous and/or selected yeasts during fermentation of plum pomace. Minimal duration of fermentation (4 to 5 d) and fastest ethanol production rate (from 12.3 to 15.5 g/L/d) were the characteristics of the studied S. cerevisiae strains. Isobutanol, 3-methyl-1-butanol, 1-heptanol, and 1-octanol were the most prevalent higher alcohols in the tested plum wine samples. The predominant ester in plum wines was ethyl acetate, ethyl lactate, amyl acetate, isoamyl acetate, and ethyl palmitate, esters responsible for the floral and fruity olfactory tones, were also present in large amounts. Also, the use of S. cerevisiae strains resulted in the production of plum wines with better sensory characteristics than ones produced with other investigated yeasts. Obtained results are significant since there is limited data on the compounds responsible for the unique flavor of plum wine, as well as on the impact of different yeast starter cultures application on the overall quality of fruit wines. © 2017 Institute of Food Technologists®.

  14. Characterization of lactic acid bacteria isolated from infant faeces as potential probiotic starter cultures for fermented sausages.

    Science.gov (United States)

    Rubio, Raquel; Jofré, Anna; Martín, Belén; Aymerich, Teresa; Garriga, Margarita

    2014-04-01

    A total of 109 lactic acid bacteria isolated from infant faeces were identified by partial 16S rRNA, cpn60 and/or pheS sequencing. Lactobacillus was the most prevalent genus, representing 48% of the isolates followed by Enterococcus (38%). Lactobacillus gasseri (21%) and Enterococcus faecalis (38%) were the main species detected. A further selection of potential probiotic starter cultures for fermented sausages focused on Lactobacillus as the most technologically relevant genus in this type of product. Lactobacilli strains were evaluated for their ability to grow in vitro in the processing conditions of fermented sausages and for their functional and safety properties, including antagonistic activity against foodborne pathogens, survival from gastrointestinal tract conditions (acidity, bile and pancreatin), tyramine production, antibiotic susceptibility and aggregation capacity. The best strains according to the results obtained were Lactobacillus casei/paracasei CTC1677, L. casei/paracasei CTC1678, Lactobacillus rhamnosus CTC1679, L. gasseri CTC1700, L. gasseri CTC1704, Lactobacillus fermentum CTC1693. Those strains were further assayed as starter cultures in model sausages. L. casei/paracasei CTC1677, L. casei/paracasei CTC1678 and L. rhamnosus CTC1679 were able to lead the fermentation and dominate (levels ca. 10(8) CFU/g) the endogenous lactic acid bacteria, confirming their suitability as probiotic starter cultures. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Bio-synthesis of citric acid from single and co-culture-based fermentation technology using agro-wastes

    Directory of Open Access Journals (Sweden)

    Sohaib Rafaqat Ali

    2016-01-01

    Full Text Available Agro-based materials are primarily composed of complex polysaccharides that strengthen microbial growth for the production of industrially relevant value-added products. Therefore, in the present study, solid state fermentation (SSF was carried out using agro-based waste materials (apple pomace, peanut shell and a mixture of both apple pomace and peanut shell with 50:50 ratio as carriers/support for SSF to enhance citric acid production from single and co-culture consortia of Aspergillus ornatus and Alternaria alternata. During initial screening trial it was observed that growth media supplemented with apple pomace under SSF process of co-culture consortia presenting the preeminent 0.46 ± 0.42 mg/mL of citric acid. On partial optimization co-culture showed the maximum citric acid yield (2.644 ± 0.99 mg/mL in the presence of arginine as a nutritional ingredient at 30 °C in an apple pomace based medium at 50% moisture content with pH of 5 and substrate concentration (25 g after 48th of solid state fermentation. In conclusion, a suitable addition of fermentative substrate to the SSF medium increased fungal growth, sugar utilization and citric acid production when used in lower concentrations.

  16. Characterization of cucumber fermentation spoilage bacteria by enrichment culture and 16S rDNA cloning.

    Science.gov (United States)

    Breidt, Fred; Medina, Eduardo; Wafa, Doria; Pérez-Díaz, Ilenys; Franco, Wendy; Huang, Hsin-Yu; Johanningsmeier, Suzanne D; Kim, Jae Ho

    2013-03-01

    Commercial cucumber fermentations are typically carried out in 40000 L fermentation tanks. A secondary fermentation can occur after sugars are consumed that results in the formation of acetic, propionic, and butyric acids, concomitantly with the loss of lactic acid and an increase in pH. Spoilage fermentations can result in significant economic loss for industrial producers. The microbiota that result in spoilage remain incompletely defined. Previous studies have implicated yeasts, lactic acid bacteria, enterobacteriaceae, and Clostridia as having a role in spoilage fermentations. We report that Propionibacterium and Pectinatus isolates from cucumber fermentation spoilage converted lactic acid to propionic acid, increasing pH. The analysis of 16S rDNA cloning libraries confirmed and expanded the knowledge gained from previous studies using classical microbiological methods. Our data show that Gram-negative anaerobic bacteria supersede Gram-positive Fermincutes species after the pH rises from around 3.2 to pH 5, and propionic and butyric acids are produced. Characterization of the spoilage microbiota is an important first step in efforts to prevent cucumber fermentation spoilage. An understanding of the microorganisms that cause commercial cucumber fermentation spoilage may aid in developing methods to prevent the spoilage from occurring. © 2013 Institute of Food Technologists®

  17. Applicability of bacteriocinogenic Lactobacillus pentosus 31-1 as a novel functional starter culture or coculture for fermented sausage manufacture.

    Science.gov (United States)

    Liu, Guorong; Griffiths, Mansel W; Shang, Nan; Chen, Shangwu; Li, Pinglan

    2010-02-01

    The technological feasibility of producing fermented sausages using the bacteriocin-producing Lactobacillus pentosus 31-1, isolated from a traditional Chinese fermented meat product (Xuanwei ham), was evaluated. Strain 31-1 was used both as a single starter and in coculture for manufacture of fermented sausages. The microbiological and physicochemical properties (color, texture, and sensory quality) and the production of bacteriocin during ripening of these products were compared with those characteristics of sausages produced with a commercial meat starter. Challenge tests were performed using Listeria innocua or Staphylococcus aureus as target strains. The addition of L. pentosus 31-1 can significantly reduce L. innocua and S. aureus populations during all ripening phases. Free amino acid and free fatty acid analysis suggested that strain 31-1 might have proteolytic and lipolytic activity. The use of this strain resulted in a final product with a brighter surface and better texture and sensory profiles. A maximum bacteriocin (pentocin 31-1) concentration of 640 AU/g was detected in homogenized sausages with added L. pentosus 31-1. The bacteriocin-producing strain L. pentosus 31-1 could be used as a novel functional starter culture or coculture for sausage fermentation.

  18. Bacterial Ecology of Fermented Cucumber Rising pH Spoilage as Determined by Non-Culture Based Methods

    Science.gov (United States)

    Medina, Eduardo; Pérez-Díaz, Ilenys M.; Breidt, Fred; Hayes, Janet; Franco, Wendy; Butz, Natasha; Azcarate-Peril, María Andrea

    2016-01-01

    Fermented cucumber spoilage (FCS) characterized by rising pH and the appearance of manure and cheese like aromas is a challenge of significant economical impact for the pickling industry. Previous culture based studies identified the yeasts Pichia manshurica and Issatchenkia occidentalis, four gram positive bacteria, Lactobacillus buchneri, Lactobacillus parrafaraginis, Clostridium sp. and Propionibacterium and one gram-negative genus, Pectinatus as relevant in various stages of FCS given their ability to metabolize lactic acid. It was the objective of this study to augment the current knowledge of FCS using culture independent methods to microbiologically characterize commercial spoilage samples. Ion Torrent data and 16S rRNA cloning library analyses of samples collected from commercial fermentation tanks confirmed the presence of L. rapi and L. buchneri and revealed the presence of additional species involved in the development of FCS such as Lactobacillus namurensis, Lactobacillus acetotolerans, Lactobacillus panis, Acetobacter peroxydans, Acetobacter aceti, and Acetobacter pasteurianus at pH below 3.4. The culture independent analyses also revealed the presence of species of Veillonella and Dialister in spoilage samples with pH above 4.0 and confirmed the presence of Pectinatus spp. during lactic acid degradation at the higher pH. Acetobacter spp. were successfully isolated from commercial samples collected from tanks subjected to air purging by plating on Mannitol Yeast Peptone agar. In contrast, Lactobacillus spp. were primarily identified in samples of FCS collected from tanks not subjected to air purging for more than 4 months. Thus, it is speculated that oxygen availability may be a determining factor in the initiation of spoilage and the leading microbiota. Practical Application Understanding of the underlying microbiology and biochemistry driving FCS is essential to enhancing the sodium chloride (NaCl)-free cucumber fermentation technology and in

  19. Lactic Acid Bacterial Starter Culture with Antioxidant and γ-Aminobutyric Acid Biosynthetic Activities Isolated from Flatfish-Sikhae Fermentation.

    Science.gov (United States)

    Won, Yeong Geol; Yu, Hyun-Hee; Chang, Young-Hyo; Hwang, Han-Joon

    2015-12-01

    The aim of this study is to select a lactic acid bacterial strain as a starter culture for flatfish-Sikhae fermentation and to evaluate its suitability for application in a food system. Four strains of lactic acid bacteria isolated from commercial flatfish-Sikhae were identified and selected as starter culture candidates through investigation of growth rates, salt tolerance, food safety, and functional properties such as antioxidative and antimicrobial activities. The fermentation properties of the starter candidates were also examined in food systems prepared with these strains (candidate batch) in comparison with a spontaneous fermentation process without starter culture (control batch) at 15°C. The results showed that the candidate YG331 batch had better fermentation properties such as viable cell count, pH, and acidity than the other experimental batches, including the control batch. The results are expressed according to selection criteria based on a preliminary sensory evaluation and physiochemical investigation. Also, only a small amount of histamine was detected with the candidate YG331 batch. The radical scavenging activity of the candidate batches was better compared with the control batch, and especially candidate YG331 batch showed the best radical scavenging activity. Also, we isolated another starter candidate (identified as Lactobacillus brevis PM03) with γ-aminobutyric acid (GABA)-producing activity from commercial flatfish-Sikhae products. The sensory scores of the candidate YG331 batch were better than those of the other experimental batches in terms of flavor, color, and overall acceptance. In this study, we established selection criteria for the lactic acid bacterial starter for the flatfish-Sikhae production and finally selected candidate YG331 as the most suitable starter.

  20. COMPARATIVE EVALUTION OF CEPHALOSPORIN-C PRODUCTION IN SOLID STATE FERMENTATION AND SUBMERGED LIQUID CULTURE

    Directory of Open Access Journals (Sweden)

    Mahdi Rezazarandi

    2012-08-01

    Full Text Available The advantages of solid state fermentation (SSF utilization in producing enzymes & secondary metabolites have been shown, whereas, submerged liquid fermentation (SLF condition has the major usage in industrial production of antibiotics. As an antibiotic of B-lactams group, cephalosporin-C (CPC is indicated due to its wide effect and broad convention in treatment of infectious diseases. Regarding industrial production of CPC regularly done in SLF condition, we compared CPC production sum in SLF and SSF conditions. In this analysis, A. chrysogenum was employed, which was inoculated to SLF and SSF, while internal fermenter conditions were totally under control. After extraction of CPC, productions in two states of SLF and SSF were compared using the cylinder plate method. According to Antibiotic assay and production amount comparison, results expressed a ratio of development of production in SSF conditions to SLF conditions. Regarding previous studies on a solid state fermenter and its advantages, in this study, convenience of SSF conditions compared to SLF conditions was experimented. Also mentioning that maintaining the condition of solid state fermenter is more comfortable and practical than liquid state fermenter, using a solid based fermenter to produce antibiotics, especially CPC, can be appropriate. Considering appropriate control conditions of SSF to produce secondary metabolites, decrease in expenses, and increase of production, taking advantage of it in order to increase production parallel to modern methods, such as genetically manipulating CPC producing microorganisms are recommended to pharmacological industries. Also, to make this method applicable, further studies in industrial criterion seem necessary.

  1. The availability of a lactose medium for tea fungus culture and Kombucha fermentation

    Directory of Open Access Journals (Sweden)

    Markov S.L.

    2012-01-01

    Full Text Available Kombucha is a traditional beverage that is prepared by fermenting sucrose-sweetened black tea. A medium is inoculated with a cellulose pellicle (popularly known as a “tea fungus” or fermentation brought from previous cultivation process. Our aim was to test the possibility of obtaining a Kombucha beverage using different concentration of lactose as an alternative source of C-atoms. A traditional medium sweetened with sucrose or without sugar was used as control. Without lactose-fermenting yeast strains in tea fungus, lactose is not an adequate alternative source of the C-atom for Kombucha fermentation because it is not possible to obtain Kombucha with an appropriate acidity during a seven-day fermentation. Compared with the traditional medium, fermentation is significantly slower with high differences in acid content. In unsweetened tea inoculated with the beverage obtained from a previous traditional process, Kombucha fermentation processes and produces a beverage without sugar and alcohol. [Projekat Ministarstva nauke Republike Srbije, br. TR 31044

  2. Effects of pH and substrate concentrations on dark fermentative biohydrogen production from xylose by extreme thermophilic mixed culture.

    Science.gov (United States)

    Qiu, Chunsheng; Shi, Puyu; Xiao, Shumin; Sun, Liping

    2017-01-01

    Biohydrogen is considered as one of the most promising energy alternatives considering the climate and energy crisis. The dark fermentative hydrogen production from xylose at extreme thermophilic condition (70 °C) using mixed culture was conducted in this study. The effects of initial pH values (ranged from 5.0 to 10.0) and substrate concentrations (ranged from 2.5 to 15.0 g/L) on the hydrogen production, substrate degradation and metabolite distributions were investigated using batch-mode operations. Results showed that initial substrate pH values in the neutral region (6.0-7.0) were beneficial for hydrogen production. The fermentation at initial pH 7.0 and 7.5 g/L xylose reached an optimal hydrogen yield of 1.29 mol-H2/mol-xyloseconsumed. Ethanol, butyrate, and propionate were the major liquid metabolites. The xylose biodegradation efficiency of the mixed culture decreased sharply at high initial culture pH values. The increase of xylose concentration resulted in the accumulation of propionate and an obvious decrease in the final pH value, as well as a low hydrogen yield. Polymerase chain reaction-denaturing gradient gel electrophoresis analysis indicated that hydrogen producing bacteria were enriched by repeated culture under extreme thermophilic conditions. Also, the mixed culture was dominated with bacterial species related to Clostridium and Thermoanaerobacterium.

  3. Effect of starter culture inoculation on feed hygiene and microbial population development in fermented pig feed composed of a cereal grain mix with wet wheat distillers' grain.

    Science.gov (United States)

    Olstorpe, M; Axelsson, L; Schnürer, J; Passoth, V

    2010-01-01

    Investigating the influence of an added starter culture on the properties of fermented liquid pig feed. Diets of cereal grain blended with wet wheat distillers' grain that were either not inoculated (WWDG), inoculated with a silage starter culture at start (WWDGsc1) or at start and at each backslopping (replacement of 80% the content with fresh mixture, simulating feed outtake, WWDGsc5) were fermented for 5 days, followed by 5 days of daily backslopping. Numbers of undesirable micro-organisms (enterobacteria, moulds) were reduced in all fermentations; particularly enterobacteria in the starter culture inoculated diets. Lactobacillus plantarum present in the starter culture became dominant in diets WWDGsc1 and WWDGsc5. However, Lactobacillus panis that was dominating WWDG was also abundant in WWDGsc1 and WWDGsc5. Yeast populations were not influenced by the starter culture, with Pichia fermentans dominating all fermentations. All diets had similar chemical characteristics with the exception of a significant increase of all tested organic acids in WWDGsc5. The addition of a starter culture influences the bacterial population in fermented liquid feed, but there is also a strong impact of the flora already present in the feed ingredients. The yeast population is not influenced by adding a lactic acid bacteria (LAB) starter culture. A consortium of LAB and yeast strains adapted to the fermentation should be used as starter culture. The results suggest that it is possible to influence the current unpredictable and spontaneous process of feed fermentation when appropriate starter cultures are used. For this purpose, LAB and yeasts with desirable characteristics should be isolated.

  4. Organizational structure and continuous improvement and learning: Moderating effects of cultural endorsement of participative leadership

    OpenAIRE

    Xiaowen Huang; Joseph C Rode; Roger G. Schroeder

    2011-01-01

    Building upon the culturally endorsed implicit theory of leadership, we investigated the moderating effects of national culture on the relationship between organizational structure and continuous improvement and learning. We propose that the relationship between organic organizations (characterized by flat, decentralized structures with a wide use of multifunctional employees) and continuous improvement and learning will be stronger when national cultural endorsement for participative leaders...

  5. Fermentative hydrogen production by Clostridium butyricum CWBI1009 and Citrobacter freundii CWBI952 in pure and mixed cultures

    Directory of Open Access Journals (Sweden)

    Beckers, L.

    2010-01-01

    Full Text Available This paper investigates the biohydrogen production by two mesophilic strains, a strict anaerobe (Clostridium butyricum CWBI1009 and a facultative anaerobe (Citrobacter freundii CWBI952. They were cultured in pure and mixed cultures in serum bottles with five different carbon sources. The hydrogen yields of pure C. freundii cultures ranged from 0.09 molH2.molhexose-1 (with sucrose to 0.24 molH2.molhexose-1 (with glucose. Higher yields were obtained by the pure cultures of Cl. butyricum ranging from 0.44 molH2.molhexose-1 (with sucrose to 0.69 molH2.molhexose-1 (with lactose. This strain also fermented starch whereas C. freundii did not. However, it consumed the other substrates faster and produced hydrogen earlier than Cl. butyricum. This ability has been used to promote the growth conditions of Cl. butyricum in co-culture with C. freundii, since Cl. butyricum is extremely sensitive to the presence of oxygen which strongly inhibits H2 production. This approach could avoid the addition of any expensive reducing agents in the culture media such as L-cysteine since C. freundii consumes the residual oxygen. Thereafter, co-cultures with glucose and starch were investigated: hydrogen yields decreased from 0.53 molH2.molhexose-1 for pure Cl. butyricum cultures to 0.38 molH2.molhexose-1 for mixed culture with glucose but slightly increased with starch (respectively 0.69 and 0.73 molH2.molhexose-1. After 48 h of fermentation, metabolites analysis confirmed with microbial observation, revealed that the cell concentration of C. freundii dramatically decreased or was strongly inhibited by the development of Cl. butyricum.

  6. Coproduction of hydrogen and methane via anaerobic fermentation of cornstalk waste in continuous stirred tank reactor integrated with up-flow anaerobic sludge bed.

    Science.gov (United States)

    Cheng, Xi-Yu; Li, Qian; Liu, Chun-Zhao

    2012-06-01

    A 10 L continuous stirred tank reactor (CSTR) system was developed for a two-stage hydrogen fermentation process with an integrated alkaline treatment. The maximum hydrogen production rate reached 218.5 mL/L h at a cornstalk concentration of 30 g/L, and the total hydrogen yield and volumetric hydrogen production rate reached 58.0 mL/g-cornstalk and 0.55-0.57 L/L d, respectively. A 10 L up-flow anaerobic sludge bed (UASB) was used for continuous methane fermentation of the effluents obtained from the two-stage hydrogen fermentation. At the optimal organic loading rate of 15.0 g-COD/Ld, the COD removal efficiency and volumetric biogas production rate reached 83.3% and 4.6L/Ld, respectively. Total methane yield reached 200.9 mL/g-cornstalk in anaerobic fermentation with the effluents and alkaline hydrolysate. As a result, the total energy recovery by coproduction of hydrogen and methane with anaerobic fermentation of cornstalk reached 67.1%. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Continuous alcoholic fermentation of glucose/xylose mixtures by co-immobilized saccharomyces cerevisiae and candida shehatae

    Energy Technology Data Exchange (ETDEWEB)

    Lebeau, T.; Jouenne, T.; Junter, G.A. [Equipe de Technologie Microbienne, CNRS/Univ. de Rouen, 76 Bois Guillaume (France)

    1998-12-31

    Viable Saccharomyces cerevisiae and Candida shehatae cells were co-immobilized in a composite agar layer/microporous membrane structure. This immobilized-cell structure was placed in a vertical position between the two halves of a double-chambered, stainless-steel bioreactor of original design and applied to the continuous alcoholic fermentation of a mixture of glucose (35 g dm{sup -3}) and xylose (15 g dm{sup -3}). Various dilution rates and initial cell loadings of the gel layer were tested. Simultaneous consumption of the two sugars was always observed. The best fermentation performance was obtained at low dilution rate (0.02 h{sup -1}) with an excess of C. shehatae over S. cerevisiae in the initial cell loading of the gel (5.0 mg dry weight and 0.65 mg dry weight cm{sup -3} gel respectively): 100% of glucose and 73% of xylose were consumed with an ethanol yield coefficient of 0.48 g g total sugars{sup -1}. In these conditions, however, the ethanol production rate per unit volume of gel remained low (0.37 g h{sup -1} dm{sup -3}). Viable cell counts in gel samples after incubation highlighted significant heterogeneities in the spatial distribution of the two yeast species in both the vertical and the transverse directions. In particular, the overall cell number decreased from the bottom to the top of the agar sheet, which may explain the low ethanol productivity relative to the total gel volume. (orig.)

  8. COMETABOLIC DEGRADATION OF CHLOROALLYL ALCOHOLS IN BATCH AND CONTINUOUS CULTURES

    NARCIS (Netherlands)

    VANDERWAARDE, JJ; KOK, R; JANSSEN, DB; Waarde, J.J. van der

    1994-01-01

    The biodegradation of chloroallyl alcohols by pure and mixed bacterial cultures was investigated. Only 2-chloroallyl alcohol and cis- and trans-3-chloroallyl alcohol served as growth substrate for pure cultures. The other chloroallyl alcohols could be cometabolically degraded during growth on

  9. Short communication: Viability of culture organisms in honey-enriched acidophilus-bifidus-thermophilus (ABT)-type fermented camel milk.

    Science.gov (United States)

    Varga, L; Süle, J; Nagy, P

    2014-11-01

    The aim of this research was to monitor the survival during refrigerated storage of Lactobacillus acidophilus LA-5 (A), Bifidobacterium animalis ssp. lactis BB-12 (B), and Streptococcus thermophilus CHCC 742/2130 (T) in cultured dairy foods made from camel and, for comparison, cow milks supplemented with black locust (Robinia pseudoacacia L.) honey and fermented by an acidophilus-bifidus-thermophilus (ABT)-type culture. Two liters of dromedary camel milk and 2 L of cow milk were heated to 90 °C and held for 10 min, then cooled to 40 °C. One half of both types of milk was fortified with black locust honey at the rate of 5.0% (wt/vol), whereas the other half was devoid of honey and served as a control. The camel and cow milks with and without honey were subsequently inoculated with ABT-5 culture and were fermented at 37 °C until a pH value of 4.6 was reached. Thereafter, the probiotic fermented milks were cooled to 15 °C in ice water and were each separated into 18 fractions that were transferred in sterile, tightly capped centrifuge tubes. After 24 h of cooling at 8 °C (d 0), the samples were stored at refrigeration temperature (4 °C). Three tubes of all 4 products (i.e., fermented camel and cow milks with and without honey) were taken at each sampling time (i.e., following 0, 7, 14, 21, 28, and 35 d of storage), and the counts of characteristic microorganisms and those of certain spoilage microbes (yeasts, molds, coliforms, Escherichia coli) were enumerated. The entire experimental program was repeated twice. The results showed that addition of black locust honey at 5% to heat-treated camel and cow milks did not influence the growth and survival of starter streptococci during production and subsequent refrigerated storage of fermented ABT milks. In contrast, honey improved retention of viability of B. animalis ssp. lactis BB-12 in the camel milk-based product during storage at 4 °C up to 5 wk. No spoilage organisms were detected in any of the samples tested

  10. Production of freeze-dried lactic acid bacteria starter culture for cassava fermentation into gari

    CSIR Research Space (South Africa)

    Yao, AA

    2009-10-01

    Full Text Available Sixteen lactic acid bacteria, eight Lactobacillus plantarum, three L. pentosus, two Weissella paramesenteroides, two L. fermemtum and one Leuconostoc mesenteroides ssp. mesenteroides were previously isolated from cassava fermentation and selected...

  11. Mathematical modeling of a continuous alcoholic fermentation process in a two-stage tower reactor cascade with flocculating yeast recycle.

    Science.gov (United States)

    de Oliveira, Samuel Conceição; de Castro, Heizir Ferreira; Visconti, Alexandre Eliseu Stourdze; Giudici, Reinaldo

    2015-03-01

    Experiments of continuous alcoholic fermentation of sugarcane juice with flocculating yeast recycle were conducted in a system of two 0.22-L tower bioreactors in series, operated at a range of dilution rates (D 1 = D 2 = 0.27-0.95 h(-1)), constant recycle ratio (α = F R /F = 4.0) and a sugar concentration in the feed stream (S 0) around 150 g/L. The data obtained in these experimental conditions were used to adjust the parameters of a mathematical model previously developed for the single-stage process. This model considers each of the tower bioreactors as a perfectly mixed continuous reactor and the kinetics of cell growth and product formation takes into account the limitation by substrate and the inhibition by ethanol and biomass, as well as the substrate consumption for cellular maintenance. The model predictions agreed satisfactorily with the measurements taken in both stages of the cascade. The major differences with respect to the kinetic parameters previously estimated for a single-stage system were observed for the maximum specific growth rate, for the inhibition constants of cell growth and for the specific rate of substrate consumption for cell maintenance. Mathematical models were validated and used to simulate alternative operating conditions as well as to analyze the performance of the two-stage process against that of the single-stage process.

  12. Application of near-infrared spectroscopy for monitoring and control of cell culture and fermentation

    DEFF Research Database (Denmark)

    Cervera Padrell, Albert Emili; Petersen, Nanna; Eliasson Lantz, Anna

    2009-01-01

    fusion), and the description of process trajectories. On the basis of the review, we conclude that acceptance of NIR spectroscopy as a standard monitoring tool by the fermentation industry will necessitate considerably more on-line studies using industrially relevant—and highly challenging......Near-infrared (NIR) spectroscopy can potentially provide on-line information on substrate, biomass, product, and metabolite concentrations in fermentation processes, which could be useful for improved monitoring or control. However, several factors can negatively influence the quality...

  13. Culture Condition Improvement for Phytase Production in Solid State Fermentation by Aspergillus ficuum Using Statistical Method

    OpenAIRE

    Jafari-Tapeh, H.; Z. Hamidi-Esfahani; Azizi, M. H.

    2012-01-01

    The effective factors on phytase production by Aspergillus ficuum PTCC 5288 were studied using solid-state fermentation method in 250 ml shake flask. The effective process parameters on phytase production were identified using Plackett-Burman design. Four factors were identified of different variables, including glucose, moisture, MgSO4, and fermentation time, which were the most significant. The optimum levels of these significant parameters were determined through response surface methodolo...

  14. Improved ethanol tolerance of Saccharomyces cerevisiae in mixed cultures with Kluyveromyces lactis on high-sugar fermentation.

    Science.gov (United States)

    Yamaoka, Chizuru; Kurita, Osamu; Kubo, Tomoko

    2014-12-01

    The influence of non-Saccharomyces yeast, Kluyveromyces lactis, on metabolite formation and the ethanol tolerance of Saccharomyces cerevisiae in mixed cultures was examined on synthetic minimal medium containing 20% glucose. In the late stage of fermentation after the complete death of K. lactis, S. cerevisiae in mixed cultures was more ethanol-tolerant than that in pure culture. The chronological life span of S. cerevisiae was shorter in pure culture than mixed cultures. The yeast cells of the late stationary phase both in pure and mixed cultures had a low buoyant density with no significant difference in the non-quiescence state between both cultures. In mixed cultures, the glycerol contents increased and the alanine contents decreased when compared with the pure culture of S. cerevisiae. The distinctive intracellular amino acid pool concerning its amino acid concentrations and its amino acid composition was observed in yeast cells with different ethanol tolerance in the death phase. Co-cultivation of K. lactis seems to prompt S. cerevisiae to be ethanol tolerant by forming opportune metabolites such as glycerol and alanine and/or changing the intracellular amino acid pool. Copyright © 2014 Elsevier GmbH. All rights reserved.

  15. Cyclodextrin glycosyltransferase production by free cells of Bacillus circulans DF 9R in batch fermentation and by immobilized cells in a semi-continuous process.

    Science.gov (United States)

    Costa, Hernán; Gastón, Jorgelina Rodríguez; Lara, Julia; Martinez, Camila Ortiz; Moriwaki, Cristiane; Matioli, Graciette; Ferrarotti, Susana Alicia

    2015-06-01

    Cyclodextrin glycosyltransferase (CGTase) catalyzes starch conversion into cyclic or linear oligosaccharides, important industrial products for the complexation of non-polar substances. In this work, conditions to increase CGTase production from Bacillus circulans strain DF 9R were optimized by two systems. On one hand, free cells were grown in batch fermentation experiments to optimize aeration and pH. The highest activity (1.47 ± 0.21 U ml(-1)) was achieved after 48 h of growth, aeration of 1.5 vvm and pH regulated to 7.6. On the other hand, bacterial cells were immobilized on loofa and synthetic sponge, and used for CGTase production in a semi-continuous process. An initial biomass of 30 mg of lyophilized cells and an immobilization time of 24 h with loofa or synthetic sponge were enough to achieve increased production of CGTase: 0.91 ± 0.10 and 0.95 ± 0.11 U ml(-1), respectively. Sponges with immobilized bacteria were reused in 12 successive cycles. Besides, in our conditions, CGTase was not adsorbed onto the supports used for immobilization, which ensured the total recovery of the enzyme from the culture medium. The two CGTase production processes studied showed similar productivity and could be potentially scaled up.

  16. Dynamics in population heterogeneity during batch and continuous fermentation of Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Heins, Anna-Lena; Lencastre Fernandes, Rita; Lundin, L.

    2012-01-01

    environmental changes, which might pose stress on the cells, affect their metabolism and consequently influence the level of heterogeneity of the population. To gain a deeper understanding of population heterogeneity and the triggering phenomena, a Saccharomyces cerevisiae growth reporter strain based...... distribution during different growth stages. To further simulate which effect gradients have on population heterogeneity, glucose and ethanol perturbations during continuous cultivation were performed. Physiological changes were analyzed on single cell level by using flow cytometry followed by cell sorting...

  17. Immigrants' continuing bonds with their native culture: assimilation analysis of three interviews.

    Science.gov (United States)

    Henry, Hani M; Stiles, William B; Biran, Mia W; Mosher, James K; Brinegar, Meredith Glick; Banerjee, Prashant

    2009-06-01

    Three case studies of immigrants to the US from China, Iraq, and Mexico were used to build a theory of acculturation in immigrants by integrating the continuing bonds model, which describes mourning in bereavement with the assimilation model, which describes psychological change in psychotherapy. Participants were interviewed about the loss of their native culture and their life in the US. One participant had not fully assimilated the loss of her native culture, but used her continuing bonds with her culture as a source of solace. Another participant used his continuing bonds with his culture as a source of solace, but these bonds had become a source of conflict with the host culture. The third participant had largely assimilated the loss of his native culture such that the voices of this culture were linked via meaning bridges with the voices of the host culture, and the continuing bonds were resources that helped him in his land of immigration.

  18. Enterococcus faecium RZS C5, an interesting bacteriocin producer to be used as a co-culture in food fermentation.

    Science.gov (United States)

    Leroy, F; Foulquié Moreno, M R; De Vuyst, L

    2003-12-01

    Enterocins, bacteriocins produced by enterococci, are gaining interest because of their industrial potential. Due to its bacteriocin production, Enterococcus faecium RZS C5, a natural cheese isolate, has a strong activity towards Listeria monocytogenes. For this reason, the strain may be applicable as a bacteriocin-producing co-culture in food fermentation in order to reduce the risk on Listeria outgrowth. The strain displays remarkable bacteriocin production kinetics. Whereas most lactic acid bacteria produce bacteriocin in a growth-associated way until the beginning of the stationary phase, bacteriocin production by E. faecium RZS C5 in MRS broth at controlled pH values below 7.5 is characterised by a boost of bacteriocin activity levels in the very early growth phase. In addition, bacteriocin production kinetics are closely linked to the environmental and cultural conditions. However, no straightforward statement about the effect of environmental stress on bacteriocin production can be made since the effect is dependent on the type of stress applied. Kinetic experiments in milk and on pilot scale, applying Cheddar cheese-making conditions, have indicated that the strain may be effective as a bacteriocin-producing co-culture. Further research is needed to evaluate the use of E. faecium RZS C5 as a co-culture for the production of fermented sausage.

  19. Co-culture fermentation of peanut-soy milk for the development of a novel functional beverage.

    Science.gov (United States)

    Santos, Claudia Cristina Auler do Amaral; Libeck, Bárbara da Silva; Schwan, Rosane Freitas

    2014-09-01

    Most of the commercial probiotic products are dairy-based, and the development of non-dairy probiotic products could be an alternative for new functional products. The peanut-soy milk (PSM(1)) was inoculated with six different lactic acid bacteria (LAB), including probiotic strains and yeasts and fermentation was accomplished for 24h at 37 °C and afterwards, another 24h at ±4 °C. The Pediococcus acidilactici (UFLA BFFCX 27.1), Lactococcus lactis (CCT 0360), Lactobacillus rhamnosus (LR 32) probiotic LAB, and the Lactobacillus delbrueckii subsp. bulgaricus (LB 340) yogurt starter culture reached cell concentrations of about 8.3log CFU/mL during fermentation. However, these strains were not able to acidify the substrate when inoculated as pure culture. The Lactobacillus acidophilus (LACA 4) probiotic produced significant amounts of lactic acid (3.35 g/L) and rapidly lowered the pH (4.6). Saccharomyces cerevisiae (UFLA YFFBM 18.03) did not completely consume the available sugars in PSM and consequently produced low amounts of ethanol (0.24 g/L). In pure culture, S. cerevisiae (UFLA YFFBM 18.03), L. rhamnosus (LR 32), L. acidophilus (LACA 4), and P. acidilactici (UFLA BFFCX 27.1) promoted the increase of total amino acids (48.02%, 47.32%, 46.21% and, 44.07%, respectively). However, when in co-cultured, the strains consumed the free amino acids favoring their growth, and reaching the population of 8log CFU/mL in PSM. Lactic acid production increased, and 12 h was required to reach a pH value of 4.3. In general, the strains were more efficient in the use of available carbohydrates and release of metabolites in co-cultured than in single culture fermentations. An average of 58% and 78% of available carbohydrates was consumed when single and co-cultures were evaluated, respectively. Higher lactic acid contents were found in a binary culture of P. acidilactici (UFLA BFFCX 27.1) and L. acidophilus (LACA 4), and by co-culture of P. acidilactici (UFLA BFFCX 27.1), L

  20. Inhibitory effect of essential oils against Lactobacillus rhamnosus and starter culture in fermented milk during its shelf-life period

    Directory of Open Access Journals (Sweden)

    Cristiane Mengue Feniman Moritz

    2012-09-01

    Full Text Available The use of essential oils in foods has attracted great interest, due to their antagonistic action against pathogenic microorganisms. However, this action is undesirable for probiotic foods, as products containing Lactobacillus rhamnosus. The aim of the present study was to measure the sensitivity profile of L. rhamnosus and a yogurt starter culture in fermented milk, upon addition of increasing concentrations of cinnamon, clove and mint essential oils. Essential oils were prepared by steam distillation, and chemically characterised by gas chromatography-mass spectrometry (GC-MS and determination of density. Survival curves were obtained from counts of L. rhamnosus and the starter culture (alone and in combination, upon addition of 0.04% essential oils. In parallel, titratable acidity was monitored over 28 experimental days. Minimum inhibitory concentration values, obtained using the microdilution method in Brain Heart Infusion medium, were 0.025, 0.2 and 0.4% for cinnamon, clove and mint essential oils, respectively. Cinnamon essential oil had the highest antimicrobial activity, especially against the starter culture, interfering with lactic acid production. Although viable cell counts of L. rhamnosus were lower following treatment with all 3 essential oils, relative to controls, these results were not statistically significant; in addition, cell counts remained greater than the minimum count of 10(8CFU/mL required for a product to be considered a probiotic. Thus, although use of cinnamon essential oil in yogurt makes starter culture fermentation unfeasible, it does not prevent the application of L. rhamnosus to probiotic fermented milk. Furthermore, clove and mint essential oil caused sublethal stress to L. rhamnosus.

  1. Bio-immobilization of dark fermentative bacteria for enhancing continuous hydrogen production from cornstalk hydrolysate.

    Science.gov (United States)

    Zhao, Lei; Cao, Guang-Li; Sheng, Tao; Ren, Hong-Yu; Wang, Ai-Jie; Zhang, Jian; Zhong, Ying-Juan; Ren, Nan-Qi

    2017-11-01

    Mycelia pellets were employed as biological carrier in a continuous stirred tank reactor to reduce biomass washout and enhance hydrogen production from cornstalk hydrolysate. Hydraulic retention time (HRT) and influent substrate concentration played critical roles on hydrogen production of the bioreactor. The maximum hydrogen production rate of 14.2mmol H 2 L -1 h -1 was obtained at optimized HRT of 6h and influent concentration of 20g/L, 2.6 times higher than the counterpart without mycelia pellets. With excellent immobilization ability, biomass accumulated in the reactor and reached 1.6g/L under the optimum conditions. Upon further energy conversion analysis, continuous hydrogen production with mycelia pellets gave the maximum energy conversion efficiency of 17.8%. These results indicate mycelia pellet is an ideal biological carrier to improve biomass retention capacity of the reactor and enhance hydrogen recovery efficiency from lignocellulosic biomass, and meanwhile provides a new direction for economic and efficient hydrogen production process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Screening of probiotic cultures intended for processing of fermented foods for their ability to produce biogenic amines

    Directory of Open Access Journals (Sweden)

    Radka Burdychová

    2008-01-01

    Full Text Available The contemporary trend is using probiotic cultures in fermented food production. They can be used as starter cultures and for their positive effect on human health. Probiotics are defined as living microorganisms present in food which consumed in adequate amounts affects positively the intestinal microflora’s composition and balance and thus human health itself. Cultures of these bacteria have to be of human origin and be able to survive the passage through the gastrointestinal tract. They also have to be able to multiply on the site of action (in intestine and must not be toxic or pathogenic. Unfortunately, even some probiotic cultures can be counted among potential producers of biogenic amines, so their testing for the presence of biogenic amines is necessary (BURDYCHOVÁ, 2007.The aim of this study was screening of 26 types of bacterial cultures (SACCO, Italy as probiotic cultures for their ability to produce biogenic amines tyramine and histamine. Cultivation in decarboxy­lating medium (BOVER-CID and HOLZAPFEL, 1999, HPLC descibed by BURDYCHOVÁ and DOHNAL (2007, and PCR detection of genes coding enzymes tyrosindecarboxylase and histidindecarboxylase, participating in formation of biogenic amines (COTON et al., 2004, were used as the screening methods. 19 strains of Lactobacillus spp., 3 strains of Bifidobacterium spp., 2 strains of Pediococcus spp. and 2 strains of Enterococcus spp. were examined by the methods mentioned above. The tyramine production was detected at 8 strains of Lactobacillus spp., 3 strains of Bifidobacterium spp. and 2 strains of Enterococcus spp., whereas no tested cultures were found to be able to produce histamine.The strains at which production of biogenic amines tyramine and histamine wasn’t detected are suitable for fermented food processing. When the strains at which production of tyramine was demonstrated were used in food processing, a control of concentration of this biogenic amine in final product

  3. Looking for practical tools to achieve next-future applicability of dark fermentation to produce bio-hydrogen from organic materials in Continuously Stirred Tank Reactors.

    Science.gov (United States)

    Tenca, A; Schievano, A; Lonati, S; Malagutti, L; Oberti, R; Adani, F

    2011-09-01

    This study aimed at finding applicable tools for favouring dark fermentation application in full-scale biogas plants in the next future. Firstly, the focus was obtaining mixed microbial cultures from natural sources (soil-inocula and anaerobically digested materials), able to efficiently produce bio-hydrogen by dark fermentation. Batch reactors with proper substrate (1 gL(glucose)(-1)) and metabolites concentrations, allowed high H(2) yields (2.8 ± 0.66 mol H(2)mol(glucose)(-1)), comparable to pure microbial cultures achievements. The application of this methodology to four organic substrates, of possible interest for full-scale plants, showed promising and repeatable bio-H(2) potential (BHP=202 ± 3 NL(H2)kg(VS)(-1)) from organic fraction of municipal source-separated waste (OFMSW). Nevertheless, the fermentation in a lab-scale CSTR (nowadays the most diffused typology of biogas-plant) of a concentrated organic mixture of OFMSW (126 g(TS)L(-1)) resulted in only 30% of its BHP, showing that further improvements are still needed for future full-scale applications of dark fermentation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Culture medium optimization for osmotolerant yeasts by use of a parallel fermenter system and rapid microbiological testing.

    Science.gov (United States)

    Pfannebecker, Jens; Schiffer-Hetz, Claudia; Fröhlich, Jürgen; Becker, Barbara

    2016-11-01

    In the present study, a culture medium for qualitative detection of osmotolerant yeasts, named OM, was developed. For the development, culture media with different concentrations of glucose, fructose, potassium chloride and glycerin were analyzed in a Biolumix™ test incubator. Selectivity for osmotolerant yeasts was guaranteed by a water activity (aw)-value of 0.91. The best results regarding fast growth of Zygosaccharomyces rouxii (WH 1002) were achieved in a culture medium consisting of 45% glucose, 5% fructose and 0.5% yeast extract and in a medium with 30% glucose, 10% glycerin, 5% potassium chloride and 0.5% yeast extract. Substances to stimulate yeast fermentation rates were analyzed in a RAMOS® parallel fermenter system, enabling online measurement of the carbon dioxide transfer rate (CTR) in shaking flasks. Significant increases of the CTR was achieved by adding especially 0.1-0.2% ammonium salts ((NH4)2HPO4, (NH4)2SO4 or NH4NO3), 0.5% meat peptone and 1% malt extract. Detection times and the CTR of 23 food-borne yeast strains of the genera Zygosaccharomyces, Torulaspora, Schizosaccharomyces, Candida and Wickerhamomyces were analyzed in OM bouillon in comparison to the selective culture media YEG50, MYG50 and DG18 in the parallel fermenter system. The OM culture medium enabled the detection of 102CFU/g within a time period of 2-3days, depending on the analyzed yeast species. Compared with YEG50 and MYG50 the detection times could be reduced. As an example, W. anomalus (WH 1021) was detected after 124h in YEG50, 95.5h in MYG50 and 55h in OM bouillon. Compared to YEG50 the maximum CO2 transfer rates for Z. rouxii (WH 1001), T. delbrueckii (DSM 70526), S. pombe (DSM 70576) and W. anomalus (WH 1016) increased by a factor ≥2.6. Furthermore, enrichment cultures of inoculated high-sugar products in OM culture medium were analyzed in the Biolumix™ system. The results proved that detection times of 3days for Z. rouxii and T. delbrueckii can be realized by

  5. Gradient simulation experiments for targeting population heterogeneity in continuous Saccharomyces cerevisiae fermentation

    DEFF Research Database (Denmark)

    Heins, Anna-Lena; Lencastre Fernandes, Rita; Lundin, L.

    of population heterogeneity, a Saccharomyces cerevisiae growth reporter strain based on the expression of green fluorescent protein (GFP) was constructed which allows to perform single cell analysis, and thereby created the possibility to map population heterogeneity. A factorial design experiment of the growth...... reporter strain demonstrated a highly dynamic behaviour with regards to subpopulation distribution during the different growth stages. To simulate which effect glucose gradients, often seen in large scale cultivations, have on population heterogeneity, glucose perturbations during continuous cultivation...... of the growth rate reporter strain was performed and the physiological changes were analysed on a single cell level. From the simulation experiment it could be demonstrated that glucose had a clear influence on subpopulation distribution....

  6. Yeast-yeast interactions revealed by aromatic profile analysis of Sauvignon Blanc wine fermented by single or co-culture of non-Saccharomyces and Saccharomyces yeasts.

    Science.gov (United States)

    Sadoudi, Mohand; Tourdot-Maréchal, Raphaëlle; Rousseaux, Sandrine; Steyer, Damien; Gallardo-Chacón, Joan-Josep; Ballester, Jordi; Vichi, Stefania; Guérin-Schneider, Rémi; Caixach, Josep; Alexandre, Hervé

    2012-12-01

    There has been increasing interest in the use of selected non-Saccharomyces yeasts in co-culture with Saccharomyces cerevisiae. The main reason is that the multistarter fermentation process is thought to simulate indigenous fermentation, thus increasing wine aroma complexity while avoiding the risks linked to natural fermentation. However, multistarter fermentation is characterised by complex and largely unknown interactions between yeasts. Consequently the resulting wine quality is rather unpredictable. In order to better understand the interactions that take place between non-Saccharomyces and Saccharomyces yeasts during alcoholic fermentation, we analysed the volatile profiles of several mono-culture and co-cultures. Candida zemplinina, Torulaspora delbrueckii and Metschnikowia pulcherrima were used to conduct fermentations either in mono-culture or in co-culture with S. cerevisiae. Up to 48 volatile compounds belonging to different chemical families were quantified. For the first time, we show that C. zemplinina is a strong producer of terpenes and lactones. We demonstrate by means of multivariate analysis that different interactions exist between the co-cultures studied. We observed a synergistic effect on aromatic compound production when M. pulcherrima was in co-culture with S. cerevisiae. However a negative interaction was observed between C. zemplinina and S. cerevisiae, which resulted in a decrease in terpene and lactone content. These interactions are independent of biomass production. The aromatic profiles of T. delbrueckii and S. cerevisiae in mono-culture and in co-culture are very close, and are biomass-dependent, reflecting a neutral interaction. This study reveals that a whole family of compounds could be altered by such interactions. These results suggest that the entire metabolic pathway is affected by these interactions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Validation of a high-throughput fermentation system based on online monitoring of biomass and fluorescence in continuously shaken microtiter plates

    Directory of Open Access Journals (Sweden)

    Kensy Frank

    2009-06-01

    Full Text Available Abstract Background An advanced version of a recently reported high-throughput fermentation system with online measurement, called BioLector, and its validation is presented. The technology combines high-throughput screening and high-information content by applying online monitoring of scattered light and fluorescence intensities in continuously shaken microtiter plates. Various examples in calibration of the optical measurements, clone and media screening and promoter characterization are given. Results Bacterial and yeast biomass concentrations of up to 50 g/L cell dry weight could be linearly correlated to scattered light intensities. In media screening, the BioLector could clearly demonstrate its potential for detecting different biomass and product yields and deducing specific growth rates for quantitatively evaluating media and nutrients. Growth inhibition due to inappropriate buffer conditions could be detected by reduced growth rates and a temporary increase in NADH fluorescence. GFP served very well as reporter protein for investigating the promoter regulation under different carbon sources in yeast strains. A clone screening of 90 different GFP-expressing Hansenula polymorpha clones depicted the broad distribution of growth behavior and an even stronger distribution in GFP expression. The importance of mass transfer conditions could be demonstrated by varying filling volumes of an E. coli culture in 96 well MTP. The different filling volumes cause a deviation in the culture growth and acidification both monitored via scattered light intensities and the fluorescence of a pH indicator, respectively. Conclusion The BioLector technology is a very useful tool to perform quantitative microfermentations under engineered reaction conditions. With this technique, specific yields and rates can be directly deduced from online biomass and product concentrations, which is superior to existing technologies such as microplate readers or optode

  8. Quantifying the significance of phage attack on starter cultures: a mechanistic model for population dynamics of phage and their hosts isolated from fermenting sauerkraut.

    Science.gov (United States)

    Mudgal, P; Breidt, F; Lubkin, S R; Sandeep, K P

    2006-06-01

    We investigated the possibility of using starter cultures in sauerkraut fermentation and thereby reducing the quantity of salt used in the process. This, in turn, would reduce the amount of waste salt that would enter in our water resources. Phage, naturally present in sauerkraut fermentation, could potentially affect the starter cultures introduced. Thus, a mechanistic mathematical model was developed to quantify the growth kinetics of the phage and starter cultures. The model was validated by independent experiments with two Leuconostoc mesenteroides strains isolated from sauerkraut and their corresponding phage. Model simulations and experimental evidence showed the presence of phage-resistant cell populations in starter cultures which replaced phage-sensitive cells, even when the initial phage density (P(0)) and multiplicity of infection (MOI) were low (P(0) temperature and pH, should be considered to make the model applicable to commercial fermentations.

  9. Optimal control of hydrogen production in a continuous anaerobic fermentation bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Aceves-Lara, Cesar-Arturo [INRA, UMR792, Ingenierie des Systemes Biologiques et des Procedes, Toulouse (France); CNRS, UMR5504, Toulouse, France 135 Avenue de Rangueil, Toulouse Cedex F-31077 (France); INRA, UR050, Laboratoire de Biotechnologie de l' Environnement, Avenue des Etangs, Narbonne F-11100 (France); Latrille, Eric; Steyer, Jean-Philippe [INRA, UR050, Laboratoire de Biotechnologie de l' Environnement, Avenue des Etangs, Narbonne F-11100 (France)

    2010-10-15

    This paper addresses the problem of optimization of hydrogen production in continuous anaerobic digesters using a model predictive control (MPC) strategy. The process is described by a dynamic nonlinear model. The influent concentration of molasses together with the effluent substrate and product concentrations of acetate, propionate, butyrate and biomass were estimated by an asymptotic online observer from measurements of gas composition in H{sub 2} and CO{sub 2} and gas flow rate. The observer was tested experimentally before to apply MPC online. The combined strategy (MPC and observer) was used in order to optimize a bioreactor of 2 L. The hydrogen production was increased by 75% up to 8.27mL{sub H{sub 2}} L{sup -1}min{sup -1}, using the influent flow rate as the main control variable while keeping the conversion of the influent concentration higher than 95% and maintaining the temperature at 37 C and pH at 5.5. (author)

  10. Fermentation of model hemicelluloses by Prevotella strains and Butyrivibrio fibrisolvens in pure culture and in ruminal enrichment cultures

    Science.gov (United States)

    Hemicelluloses are major components of plant biomass, but their fermentation in the rumens of cattle and other ruminants is poorly understood. We compared four species of the ruminally dominant genus Prevotella and the well-known hemicellulose utilizer, Butyrivibrio fibrisolvens, with respect to deg...

  11. Monitoring the ecology of Bacillus during Daqu incubation, a fermentation starter, using culture-dependent and culture-independent methods

    NARCIS (Netherlands)

    Zheng, Y.; Zheng, X.; Han, B.Z.; Han, J.S.; Nout, M.J.R.; Chen, J.Y.

    2013-01-01

    Daqu, a traditional fermentation starter, has been used to produce attractively flavored foods such as vinegar and Chinese liquor for thousands of years. Although Bacillus spp. are one of the dominant microorganisms in Daqu, more precise information is needed to reveal why and how Bacillus became

  12. Statistical culture-based strategies to enhance chlamydospore production by Trichoderma harzianum SH2303 in liquid fermentation.

    Science.gov (United States)

    Li, Ya-Qian; Song, Kai; Li, Ya-Chai; Chen, Jie

    2016-08-01

    Trichoderma-based formulations are applied as commercial biocontrol agents for soil-borne plant pathogens. Chlamydospores are active propagules in Trichoderma spp., but their production is currently limited due to a lack of optimal liquid fermentation technology. In this study, we explored response surface methodologies for optimizing fermentation technology in Trichoderma SH2303. Our initial studies, using the Plackett-Burman design, identified cornmeal, glycerol, and initial pH levels as the most significant factors (P<0.05) for enhancing the production of chlamydospores. Subsequently, we applied the Box-Behnken design to study the interactions between, and optimal levels of, a number of factors in chlamydospore production. These statistically predicted results indicated that the highest number of chlamydospores (3.6×10(8) spores/ml) would be obtained under the following condition: corn flour 62.86 g/L, glycerol 7.54 ml/L, pH 4.17, and 6-d incubation in liquid fermentation. We validated these predicted values via three repeated experiments using the optimal culture and achieved maximum chlamydospores of 4.5×10(8) spores/ml, which approximately a 8-fold increase in the number of chlamydospores produced by T. harzianum SH2303 compared with that before optimization. These optimized values could help make chlamydospore production cost-efficient in the future development of novel biocontrol agents.

  13. Hydrolytic activity of Virgibacillus sp. SK37, a starter culture of fish sauce fermentation, and its cell-bound proteinases.

    Science.gov (United States)

    Sinsuwan, Sornchai; Rodtong, Sureelak; Yongsawatdigul, Jirawat

    2012-08-01

    Fish sauce production relies on a natural fermentation process requiring 12-18 months for process completion. Virgibacillus sp. SK37 has been shown to be a potential strain for fish sauce acceleration. However, hydrolytic activity of proteinases bound at cell surface of this strain has not been well elucidated. Addition of 0.2 % CaCl(2) (w/w) in conjunction with starter cultures of Virgibacillus sp. SK 37 increased protein hydrolysis as measured by α-amino group content throughout fermentation (P bound proteinases from Virgibacillus sp. SK 37 were extracted into a free form by incubating the washed cells in Ca(2+)-free buffer at 37 °C for 2 h. Cell-bound proteinases revealed molecular mass of 19, 20, 22, 32, 34, and 44 kDa based on a synthetic peptide zymogram. The proteinases showed subtilisin-like serine characteristics with the highest activity at 50 °C and pH 8 and 11. Activity of the extracted proteinases increased ~4 times at ≥100 mM CaCl(2). In addition, CaCl(2) enhanced thermal stability of the extracted proteinases. Enzymes showed proteolytic activity in either the absence or presence of 10 and 25 % NaCl toward fish muscle, soy protein isolate, and casein substrates. Cell-bound proteinases were likely to play an important role in protein hydrolysis during fish sauce fermentation.

  14. The Presence of Salt and a Curing Agent Reduces Bacteriocin Production by Lactobacillus sakei CTC 494, a Potential Starter Culture for Sausage Fermentation

    OpenAIRE

    Leroy, Frédéric; Vuyst, Luc De

    1999-01-01

    The specific conditions in the batter of raw fermented sausages may reduce the efficiency of bacteriocin-producing starter cultures. In this work, using in vitro fermentation, we found that sodium chloride and sodium nitrite interfere with the growth of Lactobacillus sakei CTC 494, an organism which produces the antilisterial bacteriocin sakacin K. Because sakacin K production follows primary metabolite kinetics, a decrease in cell formation resulted in a decrease in sakacin K production as w...

  15. Increased biohydrogen yields, volatile fatty acid production and substrate utilisation rates via the electrodialysis of a continually fed sucrose fermenter.

    Science.gov (United States)

    Jones, Rhys Jon; Massanet-Nicolau, Jaime; Mulder, Martijn J J; Premier, Giuliano; Dinsdale, Richard; Guwy, Alan

    2017-04-01

    Electrodialysis (ED) removed volatile fatty acids (VFAs) from a continually-fed, hydrogen-producing fermenter. Simultaneously, electrochemical removal and adsorption removed gaseous H2 and CO2, respectively. Removing VFAs via ED in this novel process increased H2 yields by a factor of 3.75 from 0.24molH2mol-1hexose to 0.90molH2mol-1hexose. VFA production and substrate utilisation rates were consistent with the hypothesis that end product inhibition arrests H2 production. The methodology facilitated the recovery of 37g of VFAs, and 30L H2 that was more than 99% pure, both of which are valuable, energy dense chemicals. Typically, short hydraulic and solid retention times, and depressed pH levels are used to suppress methanogenesis, but this limits H2 production. To produce H2 from real world, low grade biomass containing complex carbohydrates, longer hydraulic retention times (HRTs) are required. The proposed system increased H2 yields via increased substrate utilisation over longer HRTs. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  16. Cross-cultural acceptance of a traditional yoghurt-like product made from fermented cereal.

    Science.gov (United States)

    Akissoé, Noël H; Sacca, Carole; Declemy, Anne-Laure; Bechoff, Aurelie; Anihouvi, Victor B; Dalodé, Générose; Pallet, Dominique; Fliedel, Géneviève; Mestres, Christian; Hounhouigan, Joseph D; Tomlins, Keith I

    2015-07-01

    Akpan is a traditional ready-to-drink fermented yoghurt-like cereal beverage consumed in urban and rural areas in Benin. With the aim of adapting the product to new local and export markets, this work maps African and European consumer preferences for different types of Akpan. A sensory profile of Akpan was created and consumer tests were conducted with 103 consumers of African origin and 74 consumers of European origin. Consumer acceptance was significantly correlated with fermented odour (r = -0.94) and milky taste (r = 0.92-0.97) attributes. Cluster analysis revealed different behaviour by African and European consumers with respect to acceptability of Akpan; European consumers did not like the sour taste and African consumers liked an intense sweet milky taste. This study provides information on how Akpan, and other fermented yoghurt-type cereal products, could be adapted to African and European consumer preferences. © 2014 Society of Chemical Industry.

  17. Effect of fermentation conditions on biohydrogen production from cassava starch by anaerobic mixed cultures

    Science.gov (United States)

    Tien, Hai M.; Le, Kien A.; Tran, An T.; Le, Phung K.

    2016-06-01

    In this work, a series of batch tests were conducted to investigate the effect of pH, temperature, fermentation time, and inoculums ratio to hydrogen production using cassava starch as a substrate. The statistical analysis of the experiment indicated that the significant effects for the fermentation yield were the main effect of temperature, pH and inoculums ratio. It was fouund that the suitable fermentation conditions of biohydrogen production should be at temperature 40 ° C; pH 6.5, inoculums to medium ratio 10 % and COD operation at 4800 g/mL. The maximum value of hydrogen volume produced was 76.22 mL. These affected has been evaluated and the result can be used as an reference for the pilot or industrial biohydrogen production.

  18. Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate

    DEFF Research Database (Denmark)

    Crafack, Michael; Keul, Hanna; Eskildsen, Carl Emil Aae

    2014-01-01

    The sensory quality of chocolate is widely determined by the qualitative and quantitative composition of volatile compounds resulting from microbial metabolism during fermentation, and Maillard reactions taking place during drying, roasting and conching. The influence of applying mixed starter...... in roasted cocoa liquors and finished chocolates. 19 of the 56 volatile compounds identified in the chocolates were found in significantly higher amounts in the tray fermented sample, whilst significantly higher amounts of 2-methoxyphenol was measured in the two inoculated chocolates. The P. kluyveri...... inoculated chocolate was characterized by a significantly higher concentration of phenylacetaldehyde and the K. marxianus inoculated chocolate by significantly higher amounts of benzyl alcohol, phenethyl alcohol, benzyl acetate and phenethyl acetate compared to a spontaneously fermented control. Sensory...

  19. Bacillus amyloliquefaciens ssp. plantarum strains as potential protective starter cultures for the production of Bikalga, an alkaline fermented food

    DEFF Research Database (Denmark)

    Compaor, C.S.; Nielsen, D.S.; Sawadogo-Lingani, H.

    2013-01-01

    and fungi. Antimicrobial activity against Bacillus cereus was produced in H. sabdariffa seed-based medium. PCR results revealed that the isolates have potential for the lipopeptides iturin, fengycin, surfactin, the polyketides difficidin, macrolactin, bacillaene and the dipeptide bacilysin production. Ultra....... They produced several lipopeptide antibiotics and showed good potential for biological control of Bikalga. Significance and Impact of the Study: Pathogenic bacteria often occur in spontaneous food fermentations. This is the first report to identify indigenous B. amyloliquefaciens ssp. plantarum strains...... as potential protective starter cultures for safeguarding Bikalga....

  20. Isolation and characterisation of resistant-to-fermentation carbohydrate polymers from cultures of Rhizopus nigricans grown on agrofood waste materials.

    Science.gov (United States)

    Hellín, P; Laencina, J; Ros, J M

    2003-11-01

    Rhizopus nigricans was cultivated in a liquid medium using lemon, mandarin, orange, pear and melon peel or artichoke bracts as the carbon source. In all cultures, a carbohydrate polymer fraction remained resistant to fermentation. These fractions were isolated in gram amounts and characterised. The molecular weight distribution of the fractions and its sugar composition resembles those of the hairy-regions of the pectins. In the fractions, four main carbohydrates were found: 4-7 mol% Rha, 42-59 mol% Ara, 7-14 mol% Gal, 17-33 mol% GalA.

  1. Interactions between Clostridium beijerinckii and Geobacter metallireducens in co-culture fermentation with anthrahydroquinone-2, 6-disulfonate (AH2QDS) for enhanced biohydrogen production from xylose.

    Science.gov (United States)

    Zhang, Xinyu; Ye, Xiaofeng; Finneran, Kevin T; Zilles, Julie L; Morgenroth, Eberhard

    2013-01-01

    To enhance biohydrogen production, Clostridium beijerinckii was co-cultured with Geobacter metallireducens in the presence of the reduced extracellular electron shuttle anthrahydroquinone-2, 6-disulfonate (AH(2)QDS). In the co-culture system, increases of up to 52.3% for maximum cumulative hydrogen production, 38.4% for specific hydrogen production rate, 15.4% for substrate utilization rate, 39.0% for substrate utilization extent, and 34.8% for hydrogen molar yield in co-culture fermentation were observed compared to a pure culture of C. beijerinckii without AH(2)QDS. G. metallireducens grew in the co-culture system, resulting in a decrease in acetate concentration under co-culture conditions and a presumed regeneration of AH(2)QDS from AQDS. These co-culture results demonstrate metabolic crosstalk between the fermentative bacterium C. beijerinckii and the respiratory bacterium G. metallireducens and suggest a strategy for industrial biohydrogen production. Copyright © 2012 Wiley Periodicals, Inc.

  2. Clostridium difficile colonization and antibiotics response in PolyFermS continuous model mimicking elderly intestinal fermentation

    Directory of Open Access Journals (Sweden)

    Sophie Fehlbaum

    2016-12-01

    Full Text Available Abstract Background Clostridium difficile (CD, a spore-forming and toxin-producing bacterium, is the main cause for antibiotic-associated diarrhea in the elderly. Here we investigated CD colonization in novel in vitro fermentation models inoculated with immobilized elderly fecal microbiota and the effects of antibiotic treatments. Methods Two continuous intestinal PolyFermS models inoculated with different immobilized elder microbiota were used to investigate selected factors of colonization of CD in proximal (PC, model 1 and transverse-distal (TDC, model 1 and 2 colon conditions. Colonization of two CD strains of different PCR ribotypes, inoculated as vegetative cells (ribotype 001, model 1 or spores (ribotypes 001 and 012, model 2, was tested. Treatments with two antibiotics, ceftriaxone (daily 150 mg L−1 known to induce CD infection in vivo or metronidazole (twice daily 333 mg L−1 commonly used to treat CD, were investigated in TDC conditions (model 2 for their effects on gut microbiota composition (qPCR, 16S pyrosequencing and activity (HPLC, CD spore germination and colonization, and cytotoxin titer (Vero cell assay. Results CD remained undetected after inoculating vegetative cells in PC reactors of model 1, but was shown to colonize TDC reactors of both models, reaching copy numbers of up to log10 8 mL−1 effluent with stable production of toxin correlating with CD cell numbers. Ceftriaxone treatment in TDC reactors showed only small effects on microbiota composition and activity and did not promote CD colonization compared to antibiotic-free control reactor. In contrast, treatment with metronidazole after colonization of CD induced large modifications in the microbiota and decreased CD numbers below the detection limit of the specific qPCR. However, a fast CD recurrence was measured only 2 days after cessation of metronidazole treatment. Conclusions Using our in vitro fermentation models, we demonstrated that stable CD

  3. Oxygen availability and strain combination modulate yeast growth dynamics in mixed culture fermentations of grape must with Starmerella bacillaris and Saccharomyces cerevisiae.

    Science.gov (United States)

    Englezos, Vasileios; Cravero, Francesco; Torchio, Fabrizio; Rantsiou, Kalliopi; Ortiz-Julien, Anne; Lambri, Milena; Gerbi, Vincenzo; Rolle, Luca; Cocolin, Luca

    2018-02-01

    Starmerella bacillaris (synonym Candida zemplinina) is a non-Saccharomyces yeast that has been proposed as a co-inoculant of selected Saccharomyces cerevisiae strains in mixed culture fermentations to enhance the analytical composition of the wines. In order to acquire further knowledge on the metabolic interactions between these two species, in this study we investigated the impact of oxygen addition and combination of Starm. bacillaris with S. cerevisiae strains on the microbial growth and metabolite production. Fermentations were carried out under two different conditions of oxygen availability. Oxygen availability and strain combination clearly influenced the population dynamics throughout the fermentation. Oxygen concentration increased the survival time of Starm. bacillaris and decreased the growth rate of S. cerevisiae strains in mixed culture fermentations, whereas it did not affect the growth of the latter in pure culture fermentations. This study reveals new knowledge about the influence of oxygen availability on the successional evolution of yeast species during wine fermentation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Evaluation of Two Lactic Acid Bacteria Starter Cultures for the Fermentation of Natural Black Table Olives (Olea europaea L cv Kalamon).

    Science.gov (United States)

    Papadelli, Marina; Zoumpopoulou, Georgia; Georgalaki, Marina; Anastasiou, Rania; Manolopoulou, Eugenia; Lytra, Ioanna; Papadimitriou, Konstantinos; Tsakalidou, Effie

    2015-01-01

    The production of Greek-style natural black table olives remains an empirical process relying on spontaneous fermentation despite its economic significance. For this reason producers often resort to increased NaCl concentration of the brine to secure quality of the product. In this study we employ two lactic acid bacteria Leuconostoc mesenteroides subsp. mesenteroides Lm139 and Lactobacillus pentosus DSM 16366 as starters in separate laboratory low salinity fermentations of "Kalamon" cultivar olives, processed according to the Greek-style method. L. mesenteroides subsp. mesenteroides Lm139 was previously isolated from Kalamon olives laboratory spontaneous fermentations, while L. pentosus DSM 16366 was isolated from fermenting green olives prepared according to the Spanish-style method. Spontaneous olives fermentation was also performed as a control. Microbiological and physicochemical analyses of the brines revealed that the use of the starters had a significant effect on the olives fermentation, leading to a faster acidification due to the more efficient consumption of soluble sugars in the brines. The final pH value reached by each starter culture used indicates a successful lactic fermentation. The production of lactic acid by the starters and the concomitant drop of the pH value proved to inhibit enterobacteria in a shorter period of time compared to the spontaneous fermentation. Concluding, the use of either of the two lactic acid bacteria as starters in Greek-style Kalamon olives fermentation could lead to a more controllable fermentation at lower salinities. The resulting product could be of higher quality with extended shelf-life while being at the same time safer for the consumer.

  5. Culture-independent analysis of lactic acid bacteria diversity associated with mezcal fermentation.

    Science.gov (United States)

    Narváez-Zapata, J A; Rojas-Herrera, R A; Rodríguez-Luna, I C; Larralde-Corona, C P

    2010-11-01

    Mezcal is an alcoholic beverage obtained from the distillation of fermented juices of cooked Agave spp. plant stalks (agave must), and each region in Mexico with denomination of origin uses defined Agave species to prepare mezcal with unique organoleptic characteristics. During fermentation to produce mezcal in the state of Tamaulipas, not only alcohol-producing yeasts are involved, but also a lactic acid bacterial community that has not been characterized yet. In order to address this lack of knowledge on this traditional Mexican beverage, we performed a DGGE-16S rRNA analysis of the lactic acid bacterial diversity and metabolite accumulation during the fermentation of a typical agave must that is rustically produced in San Carlos County (Tamaulipas, Mexico). The analysis of metabolite production indicated a short but important malolactic fermentation stage not previously described for mezcal. The denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rRNA genes showed a distinctive lactic acid bacterial community composed mainly of Pediococcus parvulus, Lactobacillus brevis, Lactobacillus composti, Lactobacillus parabuchneri, and Lactobacillus plantarum. Some atypical genera such as Weissella and Bacillus were also found in the residual must. Our results suggest that the lactic acid bacteria could strongly be implicated in the organoleptic attributes of this traditional Mexican distilled beverage.

  6. Screening of phytase producers and optimization of culture conditions for submerged fermentation.

    Science.gov (United States)

    Coban, Hasan B; Demirci, Ali

    2014-04-01

    Phytase (myo-inositol-hexakisphosphate phosphohydrolase) is an enzyme, which breaks down phytate to inositol and orthophosphoric acid. Phytase has been used as feed additive, and in some medical applications for years. To date, phytase production has been usually performed as a solid-state fermentation with small production volumes. Therefore, the aim of this study was to increase the phytase activity in submerged fermentations by screening several microorganism strains based on the literature to select the most productive phytase producer and optimizing growth parameters such as temperature, pH, and aeration level using response surface methodology (RSM). As a result, among the four different microorganisms evaluated, Aspergillus ficuum (NRRL 3135) was selected as the most productive strain. Optimum temperature, pH, and aeration values were determined as 33 °C, 4.5, and 0.9 vvm, respectively, for A. ficuum in 2-l batch submerged phytase productions. Under these conditions, phytase activity was measured as 2.27 U/ml. Therefore, this is a unique study showing the production of phytase with A. ficuum successfully in submerged fermentation as opposed to the traditional solid-state fermentation.

  7. Evolutionary engineering in chemostat cultures for improved maltotriose fermentation kinetics in saccharomyces pastorianus lager brewing yeast

    NARCIS (Netherlands)

    Brickwedde, A.; van den Broek, M.A.; Geertman, Jan Maarten A.; Magalhães, Frederico; Kuijpers, Niels G.A.; Gibson, Brian; Pronk, J.T.; Daran, J.G.

    2017-01-01

    The lager brewing yeast Saccharomyces pastorianus, an interspecies hybrid of S. eubayanus and S. cerevisiae, ferments maltotriose, maltose, sucrose, glucose and fructose in wort to ethanol and carbon dioxide. Complete and timely conversion ("attenuation") of maltotriose by industrial S.

  8. Probiotics cultures in animal feed: Effects on ruminal fermentation, immune responses, and resistance to infectious diseases

    Science.gov (United States)

    We evaluated the effects of probiotics included in dairy cattle and mice feed on ruminal fermentation, immune responses, and resistance to Johne’s disease. To unveil the underlying mechanisms, dairy cattle were either fed Bovamine (1.04 x 10**9 cfu of Lactobacillus acidophilus NP51 plus 2.04 x 10**...

  9. Hydrogen production by hup(-) mutant and wild-type strains of Rhodobacter capsulatus from dark fermentation effluent of sugar beet thick juice in batch and continuous photobioreactors.

    Science.gov (United States)

    Uyar, Basar; Gürgan, Muazzez; Özgür, Ebru; Gündüz, Ufuk; Yücel, Meral; Eroglu, Inci

    2015-10-01

    Photofermentative production of hydrogen is a promising and sustainable process; however, it should be coupled to dark fermentation to become cost effective. In order to integrate dark fermentation and photofermentation, the suitability of dark fermenter effluents for the photofermentative hydrogen production must be demonstrated. In this study, thermophilic dark fermenter effluent (DFE) of sugar beet thick juice was used as a substrate in photofermentation process to compare wild-type and uptake hydrogenase-deficient (hup (-)) mutant strains of Rhodobacter capsulatus by means of hydrogen production and biomass growth. The tests were conducted in small-scale (50 mL) batch and large-scale (4 L) continuous photobioreactors in indoor conditions under continuous illumination. In small scale batch conditions, maximum cell concentrations were 0.92 gdcw/L c and 1.50 gdcw/L c, hydrogen yields were 34 % and 31 %, hydrogen productivities were 0.49 mmol/(L c·h) and 0.26 mmol/(Lc·h), for hup (-) and wild-type cells, respectively. In large-scale continuous conditions, maximum cell concentrations were 1.44 gdcw/L c and 1.87 gdcw/L c, hydrogen yields were 48 and 46 %, and hydrogen productivities were 1.01 mmol/(L c·h) and 1.05 mmol/(L c·h), for hup (-) and wild-type cells, respectively. Our results showed that Rhodobacter capsulatus hup (-) cells reached to a lower maximum cell concentration but their hydrogen yield and productivity were in the same range or superior compared to the wild-type cells in both batch and continuous operating modes. The maximum biomass concentration, yield and productivity of hydrogen were higher in continuous mode compared to the batch mode with both bacterial strains.

  10. Production of polyhydroxyalkanoates from fermented sugar cane molasses by a mixed culture enriched in glycogen accumulating organisms.

    Science.gov (United States)

    Bengtsson, Simon; Pisco, Ana R; Reis, Maria A M; Lemos, Paulo C

    2010-02-01

    Batch production of polyhydroxyalkanoates (PHAs) under aerobic conditions by an open mixed culture enriched in glycogen accumulating organisms (GAOs) with fermented sugar cane molasses as substrate was studied. The produced polymers contained five types of monomers, namely 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxy-2-methylbutyrate (3H2MB), 3-hydroxy-2-methylvalerate (3H2MV) and the medium chain length monomer 3-hydroxyhexanoate (3HHx). With fermented molasses as substrate, PHA was produced under concurrent consumption of stored glycogen with yields of 0.47-0.66 C-mol PHA per C-mol of total carbon substrate and with rates up to 0.65 C-mol/C-molX h. In order to investigate the role of glycogen during aerobic PHA accumulation in GAOs, synthetic single volatile fatty acids (VFAs) were used as substrates and it was found that the fate of glycogen was dependent on the type of VFA being consumed. Aerobic PHA accumulation occurred under concurrent glycogen consumption with acetate as substrate and under minor concurrent glycogen production with propionate as substrate. With butyrate and valerate as substrates, PHA accumulation occurred with the glycogen pool unaffected. The composition of the PHA was dependent on the VFA composition of the fermented molasses and was 56-70 mol-% 3HB, 13-43 mol-% 3HV, 1-23 mol-% 3HHx and 0-2 mol-% 3H2MB and 3H2MV. The high polymer yields and production rates suggest that enrichment of GAOs can be a fruitful strategy for mixed culture production of PHA from waste substrates. Copyright 2009 Elsevier B.V. All rights reserved.

  11. Delignification of disposable wooden chopsticks waste for fermentative hydrogen production by an enriched culture from a hot spring.

    Science.gov (United States)

    Phummala, Kanthima; Imai, Tsuyoshi; Reungsang, Alissara; Chairattanamanokorn, Prapaipid; Sekine, Masahiko; Higuchi, Takaya; Yamamoto, Koichi; Kanno, Ariyo

    2014-06-01

    Hydrogen (H2) production from lignocellulosic materials may be enhanced by removing lignin and increasing the porosity of the material prior to enzymatic hydrolysis. Alkaline pretreatment conditions, used to delignify disposable wooden chopsticks (DWC) waste, were investigated. The effects of NaOH concentration, temperature and retention time were examined and it was found that retention time had no effect on lignin removal or carbohydrate released in enzymatic hydrolysate. The highest percentage of lignin removal (41%) was obtained with 2% NaOH at 100°C, correlated with the highest carbohydrate released (67 mg/g pretreated DWC) in the hydrolysate. An enriched culture from a hot spring was used as inoculum for fermentative H2 production, and its optimum initial pH and temperature were determined to be 7.0 and 50°C, respectively. Furthermore, enzymatic hydrolysate from pretreated DWC was successfully demonstrated as a substrate for fermentative H2 production by the enriched culture. The maximum H2 yield and production rate were achieved at 195 mL H2/g total sugars consumed and 116 mL H2/(L·day), respectively. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  12. Effects of oxygen on Propionibacterium shermanii grown in continuous culture.

    Science.gov (United States)

    Pritchard, G G; Wimpenny, J W; Morris, H A; Lewis, M W; Hughes, D E

    1977-10-01

    Growth yields, enzyme activities, cytochrome concentrations and the rates of product formation were determined in Propionibacterium shermanii cultures grown in a chemostat with lactate as the energy source at various concentrations of oxygen. Oxygen was toxic when its partial pressure in the inflowing gas was just sufficient to give measurable dissolved oxygen concentration in the culture, when it inhibited lactate oxidation and NADH oxidase activity. Below this oxygen concentration, P. shermanii behaved as a facultative anaerobe. The adaptation from anaerobic metabolism to aerobic metabolism, however, was complex. Low partial pressures of oxygen led to decreased cytochrome and membrane-bound dehydrogenase activities and molar growth yield. Above an oxygen partial pressure of 42 mmHg in the inflowing gas stream, these changes were reversed, leading to an aerobic type of metabolism. At the highest subtoxic concentration of oxygen used (330 mmHg in the input gas), lactate was oxidized mainly to acetate and carbon dioxide and the rate of propionate formation was very low. The high molar growth yield obtained under these conditions suggested that lactate and NADH oxidation via the cytochrome electron transport system was coupled to ATP synthesis.

  13. Biomass production from glutamate fermentation wastewater by the co-culture of Candida halophila and Rhodotorula glutinis.

    Science.gov (United States)

    Zheng, Shaokui; Yang, Min; Yang, Zhifeng; Yang, Qingxiang

    2005-09-01

    In this study, the biomass production and pollutant removal from high-strength glutamate fermentation wastewater (GFW) using yeast isolates was investigated. Following enrichment culture, two species of yeasts, Candida halophila and Rhodotorula glutinis, were isolated from raw GFW with chemical oxygen demand (COD) and ammonia-nitrogen levels of 40 and 16 g l(-1), respectively. The binary mixed yeast culture was cultivated batchwise in 2.5-fold diluted GFW from which 85% of COD and 96% of reducing sugar were removed. The resulting yeast biomass contained 56% crude protein, 36.0% carbohydrate and 0.4% crude lipid. The amino acid composition of mixed yeast cells was balanced and was comparable with that of C. utilis and soybean.

  14. Bio-detoxification of phorbol esters and other anti-nutrients of Jatropha curcas seed cake by fungal cultures using solid-state fermentation.

    Science.gov (United States)

    Sharath, B S; Mohankumar, B V; Somashekar, D

    2014-03-01

    Jatropha seed cake, a byproduct after biodiesel extraction, has several anti-nutrients and toxins. Solid-state fermentation was carried out for the detoxification of the Jatropha seed cake (JSC) using different fungal cultures. The reduction in the anti-nutritional components such as tannins, phytates, saponins, lectin and protease inhibitor, and phorbol esters on 6th, 9th, and 12th day of fermentation was analyzed. The phorbol ester content in the unfermented JSC was 0.83 mg/g, and the maximum degradation of phorbol esters to the extent of 75% was observed in the case of JSC fermented with Cunninghamella echinulata CJS-90. The phytate degradation in the fermented JSC was in the range of 65-96%. There was a gradual reduction of saponin content in the JSC from 6th to 12th day, and the reduction of saponin was in the range of 55-99% after solid-state fermentation. The trypsin inhibitor activity and lectin were 1,680 trypsin inhibitor units (TIU) per gram and 0.32 hemagglutinating unit in the unfermented JSC, respectively. Trypsin inhibitor activity and lectin could not be detected in JSC after 12th day of solid-state fermentation. Tannins accounted for 0.53% in unfermented JSC, and there was a marginal increase of tannins after solid-state fermentation. The results indicate that biological detoxification could be a promising method to reduce anti-nutritional compounds and toxins in the JSC.

  15. Growth kinetics and physiological behavior of co-cultures of Saccharomyces cerevisiae and Kluyveromyces lactis, fermenting carob sugars extracted with whey.

    Science.gov (United States)

    Rodrigues, B; Lima-Costa, M E; Constantino, A; Raposo, S; Felizardo, C; Gonçalves, D; Fernandes, T; Dionísio, L; Peinado, J M

    2016-10-01

    Alcoholic fermentation of carob waste sugars (sucrose, glucose and fructose) extracted with cheese whey, by co-cultures of Saccharomyces cerevisiae and Kluyveromyces lactis has been analyzed. Growth and fermentation of S. cerevisiae in the carob-whey medium showed an inhibition of about 30% in comparison with water-extracted carob. The inhibition of K. lactis on carob-whey was greater (70%) when compared with the whey medium alone, due to osmolarity problems. Oxygen availability was a very important factor for K. lactis, influencing its fermentation performance. When K. lactis was grown alone on carob-whey medium, lactose was always consumed first, and glucose and fructose were consumed afterwards, only at high aeration conditions. In co-culture with S. cerevisiae, K. lactis was completely inhibited and, at low aeration, died after 3 days; at high aeration this culture could survive but growth and lactose fermentation were only recovered after S. cerevisiae became stationary. To overcome the osmolarity and K. lactis' oxygen problems, the medium had to be diluted and a sequential fermentative process was designed in a STR-3l reactor. K. lactis was inoculated first and, with low aeration (0.13vvm), consumed all the lactose in 48h. Then S. cerevisiae was inoculated, consuming the total of the carob sugars, and producing ethanol in a fed-batch regime. The established co-culture with K. lactis increased S. cerevisiae ethanol tolerance. This fermentation process produced ethanol with good efficiency (80g/l final concentration and a conversion factor of 0.4g ethanol/g sugar), eliminating all the sugars of the mixed waste. These efficient fermentative results pointed to a new joint treatment of agro-industrial wastes which may be implemented successfully, with economic and environmental sustainability for a bioethanol industrial proposal. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Tradition and Agency. Tracing cultural continuity and invention

    DEFF Research Database (Denmark)

    start. Yet - to update the old quip about nostalgia - tradition is not what it used to be. Twenty years ago, Eric Hobsbawm and Terence Ranger showed in The Invention of Tradition how now governments acquire legitimacy and status by creating 'traditional' ceremonies and identities. Their work helped...... revolutionize the understanding of tradition in anthropology, history and sociology, stimulating an enormous amount of research on invented and imagined traditions. However, most of this research has focussed on the cultural dynamics of specific local innovations and reactions to global developments....... The present anthology seeks to hightlight instead just how widespread the invention and revival of traditions is. The individual chapters feature a fascinating series of case studies from Africa, Asia, the Pacific, Australia, and Europe, while the editors provide and overview of how the various discussions...

  17. In vitro continuous fermentation model (PolyFermS of the swine proximal colon for simultaneous testing on the same gut microbiota.

    Directory of Open Access Journals (Sweden)

    Sabine A Tanner

    Full Text Available In vitro gut modeling provides a useful platform for a fast and reproducible assessment of treatment-related changes. Currently, pig intestinal fermentation models are mainly batch models with important inherent limitations. In this study we developed a novel in vitro continuous fermentation model, mimicking the porcine proximal colon, which we validated during 54 days of fermentation. This model, based on our recent PolyFermS design, allows comparing different treatment effects on the same microbiota. It is composed of a first-stage inoculum reactor seeded with immobilized fecal swine microbiota and used to constantly inoculate (10% v/v five second-stage reactors, with all reactors fed with fresh nutritive chyme medium and set to mimic the swine proximal colon. Reactor effluents were analyzed for metabolite concentrations and bacterial composition by HPLC and quantitative PCR, and microbial diversity was assessed by 454 pyrosequencing. The novel PolyFermS featured stable microbial composition, diversity and metabolite production, consistent with bacterial activity reported for swine proximal colon in vivo. The constant inoculation provided by the inoculum reactor generated reproducible microbial ecosystems in all second-stage reactors, allowing the simultaneous investigation and direct comparison of different treatments on the same porcine gut microbiota. Our data demonstrate the unique features of this novel PolyFermS design for the swine proximal colon. The model provides a tool for efficient, reproducible and cost-effective screening of environmental factors, such as dietary additives, on pig colonic fermentation.

  18. Continuous H2 and CH4 production from high-solid food waste in the two-stage thermophilic fermentation process with the recirculation of digester sludge.

    Science.gov (United States)

    Lee, Dong-Yeol; Ebie, Yoshitaka; Xu, Kai-Qin; Li, Yu-You; Inamori, Yuhei

    2010-01-01

    A thermophilic two-stage fermentation process using 10% total solids (TS) food waste was tested at varying organic loading rates (OLRs). The system was configured to produce H(2) and CH(4) in conjugation with the chemical oxygen demand (COD), nitrogen removal, and adjustment of the pH by returning sludge as an alkali buffer from the sludge storage tank for denitrification. The pH in the H(2) fermentation reactor was maintained in the range of 5.4-5.7 using sludge recirculation (Q(r)/Q(i) ratio 1). The average H(2) (11.1l-H(2) l(-1)-fed d(-1)) and CH(4) (47.4l-CH(4) l(-1)-fed d(-1)) production rates were achieved at OLRs of 39 (H(2) fermentation reactor) and 4.16 gCOD l(-1)d(-1) (CH(4) fermentation reactor), respectively. These results suggest that long-term stability of the continuous two-stage process can be successfully achieved by recirculation of high-alkalinity sludge of 6.7-7.5 g l(-1) as CaCO(3), without any added external chemical buffer.

  19. Effect of Continuous Fermentation of High-Sugar Fruit Must on the Viability and Morphology of Immobilized Yeast on White Foam Glass

    Directory of Open Access Journals (Sweden)

    Joanna Skwira

    2008-01-01

    Full Text Available We studied the effect of continuous fermentation of high-sugar fruit must (containing about 320 g/L of total sugars on the viability and morphology of yeast cells. The process was carried out for 2.5 months in a 4-column bioreactor at 22 °C, using the Saccharomyces bayanus S.o./1AD wine yeast strain, which was immobilized on cubes of white foam glass. During the time of continuous fermentation, the apple wine contained 11.4–16.8 % (by volume of alcohol and a total sugar concentration of 49.2–115.4 g/L. Yeast cells isolated from the carrier at the end of continuous fermentation were bigger than the cells before immobilization and were characterized by various shapes, e.g. they were elongated, large and round or pear-shaped. Some cells were connected to other cells in the form of aggregates. Some yeast cells from the second, third and fourth columns showed a substantial number of wrinkles or folds. Moreover, it was observed that yeast from the carrier in the first column was characterized by the highest viability, 70 %. In the fourth column, the percentage of viable cells was only 11 %.

  20. Evaluation of viability, metabolic activity and spore quantity in clostridial cultures during ABE fermentation.

    Science.gov (United States)

    Kolek, Jan; Branska, Barbora; Drahokoupil, Marek; Patakova, Petra; Melzoch, Karel

    2016-03-01

    Flow cytometry, in combination with fluorescent staining, was used to evaluate population heterogeneity in acetone-butanol-ethanol fermentation that was carried out with type strain Clostridium beijerinckii NCIMB 8052 and non-type C. pasteurianum NRRL B-598. A combination of propidium iodide (PI) and carboxyfluorescein diacetate (CFDA), PI plus Syto-9 and bis-oxonol (BOX) alone were employed to distinguish between active and damaged cells together with simultaneous detection of spores. These strategies provided valuable information on the physiological state of clostridia. CFDA and PI staining gave the best separation of four distinct subpopulations of enzymatically active cells, doubly stained cells, damaged cells and spores. Proportional representation of cells in particular sub-regions correlated with growth characteristics, fermentation parameters such as substrate consumption and product formation in both species under different cultivation conditions. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Biohydrogen production from xylose at extreme thermophilic temperatures (70 degrees C) by mixed culture fermentation

    DEFF Research Database (Denmark)

    Kongjan, Prawit; Min, Booki; Angelidaki, Irini

    2009-01-01

    /L. Addition of yeast extract in the cultivation medium resulted in significant improvement of hydrogen yield. The main metabolic products during xylose fermentation were acetate, ethanol, and lactate. The specific growth rates were able to fit the experimental points relatively well with Haldane equation...... acetate, formate, and ethanol at 4.25 +/- 0.10, 3.01 +/- 0.11, and 2.59 +/- 0.16 mM, respectively....

  2. Rice Fermentation Starters in Cambodia: Cultural Importance and Traditional Methods of Production

    OpenAIRE

    Yamamoto, Sota; Matsumoto, Tetsuo

    2011-01-01

    This paper focuses on the processes of producing fermentation starters in Cambodia, in order to explore the dispersal routes of starters in Southeast Asia. Spices, herbs, and a sweet ingredient are widely used to make starters in Cambodia, and many people put new starters on rice husks or straw. These widely distributed techniques may have originated in one place and later dispersed throughout Southeast Asia. Two different production processes are used in Cambodia: one based on a “rice wine c...

  3. Isolation and screening of microorganisms from a gari fermentation process for starter culture development

    CSIR Research Space (South Africa)

    Edward, VA

    2012-08-01

    Full Text Available h and then purified by streaking out repeatedly onto the appropriate growth media. The isolates were KEY TRADITIONAL STEPS FORTIFICATION STEPS POSSIBLE STARTER CULTURE... cultures and Saccharomyces cerevisiae SC 3 (CSIR culture collection) was used as a positive control for the yeast cultures. Acid production The LAB test strains (1% of an overnight culture) were inoculated into MRS broth (pH 6.2 after...

  4. Clarivate Analytics: Continued Omnia vanitas Impact Factor Culture.

    Science.gov (United States)

    Teixeira da Silva, Jaime A; Bernès, Sylvain

    2018-02-01

    This opinion paper takes aim at an error made recently by Clarivate Analytics in which it sent out an email that congratulated academics for becoming exclusive members of academia's most cited elite, the Highly Cited Researchers (HCRs). However, that email was sent out to an undisclosed number of non-HCRs, who were offered an apology shortly after, through a bulk mail, which tried to down-play the importance of the error, all the while praising the true HCRs. When Clarivate Analytics senior management was contacted, the company declined to offer an indication of the number of academics who had been contacted and erroneously awarded the HCR status. We believe that this regrettable blunder, together with the opacity offered by the company, fortify the corporate attitude about the value of the journal impact factor (JIF), and what it represents, namely a marketing tool that is falsely used to equate citations with quality, worth, or influence. The continued commercialization of metrics such as the JIF is at the heart of their use to assess the "quality" of a researcher, their work, or a journal, and contributes to a great extent to driving scientific activities towards a futile endeavor.

  5. Applicability of a Lactobacillus amylovorus strain as co-culture for natural folate bio-enrichment of fermented milk.

    Science.gov (United States)

    Laiño, Jonathan Emiliano; Juarez del Valle, Marianela; Savoy de Giori, Graciela; LeBlanc, Jean Guy Joseph

    2014-11-17

    The ability of 55 strains from different Lactobacillus species to produce folate was investigated. In order to evaluate folic acid productivity, lactobacilli were cultivated in the folate-free culture medium (FACM). Most of the tested strains needed folate for growth. The production and the extent of vitamin accumulation were distinctive features of individual strains. Lactobacillus amylovorus CRL887 was selected for further studies because of its ability to produce significantly higher concentrations of vitamin (81.2 ± 5.4 μg/L). The safety of this newly identified folate producing strain was evaluated through healthy experimental mice. No bacterial translocation was detected in liver and spleen after consumption of CRL887 during 7 days and no undesirable side effects were observed in the animals that received this strain. This strain in co-culture with previously selected folate producing starter cultures (Lactobacillus bulgaricus CRL871, and Streptococcus thermophilus CRL803 and CRL415) yielded a yogurt containing high folate concentrations (263.1 ± 2.4 μg/L); a single portion of which would provide 15% of the recommended dietary allowance. This is the first report where a Lactobacillus amylovorus strain was successfully used as co-culture for natural folate bio-enrichment of fermented milk. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Design and Investigation of PolyFermS In Vitro Continuous Fermentation Models Inoculated with Immobilized Fecal Microbiota Mimicking the Elderly Colon.

    Directory of Open Access Journals (Sweden)

    Sophie Fehlbaum

    Full Text Available In vitro gut modeling is a useful approach to investigate some factors and mechanisms of the gut microbiota independent of the effects of the host. This study tested the use of immobilized fecal microbiota to develop different designs of continuous colonic fermentation models mimicking elderly gut fermentation. Model 1 was a three-stage fermentation mimicking the proximal, transverse and distal colon. Models 2 and 3 were based on the new PolyFermS platform composed of an inoculum reactor seeded with immobilized fecal microbiota and used to continuously inoculate with the same microbiota different second-stage reactors mounted in parallel. The main gut bacterial groups, microbial diversity and metabolite production were monitored in effluents of all reactors using quantitative PCR, 16S rRNA gene 454-pyrosequencing, and HPLC, respectively. In all models, a diverse microbiota resembling the one tested in donor's fecal sample was established. Metabolic stability in inoculum reactors seeded with immobilized fecal microbiota was shown for operation times of up to 80 days. A high microbial and metabolic reproducibility was demonstrated for downstream control and experimental reactors of a PolyFermS model. The PolyFermS models tested here are particularly suited to investigate the effects of environmental factors, such as diet and drugs, in a controlled setting with the same microbiota source.

  7. Effects of organic loading rates on the continuous electricity generation from fermented wastewater using a single-chamber microbial fuel cell.

    Science.gov (United States)

    Nam, Joo-Youn; Kim, Hyun-Woo; Lim, Kyeong-Ho; Shin, Hang-Sik

    2010-01-01

    Novel coupling of single-chamber microbial fuel cells (MFCs) with granular activated carbon anodes were constructed, and their ability to produce electricity from fermented wastewater operating in continuous mode was investigated. MFCs treating real fermented wastewater can generate a power density of approximately 1884 mW/m(3), which is equivalent to approximately 51.5% of that obtained from the MFCs (3664 mW/m(3)) using acetate at the same organic loading rate (OLR) of 1.92 g/Ld. As the OLR was increased in a stepwise fashion, power density increased to 2981 mW/m(3) at an OLR of 3.84 g/Ld. The corresponding energy production was 268 kJ/m(3)d. The decrease in the power density was mainly due to the higher internal resistance resulted from complex substrate. Based on the electrode characteristics, it was verified that colloidal particulates and complex organics in the real fermented wastewater not only lowered power density but also played a role as rate-limiting factors in the continuous generation of electricity.

  8. Behaviour of marine oil-degrading bacterial populations in a continuous culture system

    Digital Repository Service at National Institute of Oceanography (India)

    Mohandass, C.; David, J.J.; Nair, S.; LokaBharathi, P.A; Chandramohan, D.

    In pursuit of developing an oil-degrading microbial consortium, we used the principle of "plasmid assisted molecular breeding" (PAMB) in a continuous culture system. Three marine bacteria, Pseudomonas putida, Brevibacterium epidermidis...

  9. Modeling Lactic Fermentation of Gowé Using Lactobacillus Starter Culture

    Directory of Open Access Journals (Sweden)

    Bettencourt de J. C. Munanga

    2016-12-01

    Full Text Available A global model of the lactic fermentation step of gowé was developed by assembling blocks hosting models for bacterial growth, lactic acid production, and the drop of pH during fermentation. Commercial strains of Lactobacillus brevis and of Lactobacillus plantarum were used; their growth was modeled using Rosso’s primary model and the gamma concept as a secondary model. The optimum values of pH and temperature were 8.3 ± 0.3, 44.6 ± 1.2 °C and 8.3 ± 0.3, 3.2 ± 37.1 °C with μmax values of 1.8 ± 0.2 and 1.4 ± 0.1 for L. brevis and L. plantarum respectively. The minimum inhibitory concentration of undissociated lactic acid was 23.7 mM and 35.6 mM for L. brevis and L. plantarum, respectively. The yield of lactic acid was five times higher for L. plantarum than for L. brevis, with a yield of glucose conversion to lactic acid close to 2.0 for the former and 0.8 for the latter. A model was developed to predict the pH drop during gowé fermentation. The global model was partially validated during manufacturing of gowé. The global model could be a tool to aid in the choice of suitable starters and to determine the conditions for the use of the starter.

  10. Cross-Cultural Communication and the Continuity of Cultures: The Role of Intercultural Dialogue

    DEFF Research Database (Denmark)

    Bouchet, Dominique

    2012-01-01

    cultural contexts influence interpersonal communication. We need to know how intercultural communication affects the mobility and permanency of cultures. We need to know what sustains our core values and what might be harmful to them. We need a clear definition of what intercultural communication is about...

  11. Effect of culture conditions on lipolytic enzyme production by Penicillium candidum in a solid state fermentation.

    Science.gov (United States)

    Ortiz-Vázquez, E; Granados-Baeza, M; Riveramuñoz, G

    1993-01-01

    Lipolytic enzymes were produced using wheat bran as substrate in a solid state fermentation with Penicillium candidum. The best production of lipolytic activity occurred at 29 degrees C. One hundred micromoles of free butyric acid (FBA) was released from tributyrin by 1 mL of cell free supernatant in the absence of control of environmental relative humidity. When a closed chamber saturated with water vapour was used the lipolytic activity increased to 320 micromoles of free butyric acid. The best initial reaction pH was 7.0. The highest activity, 480 micromoles of FBA, was obtained at a moisture content of 67.5 % of saturation.

  12. Technological performance of the enterocin A producer Enterococcus faecium MMRA as a protective adjunct culture to enhance hygienic and sensory attributes of traditional fermented milk `Rayeb?

    OpenAIRE

    Rehaiem, Amel; Martínez Fernández, Beatriz; Manai, Mohamed; Rodríguez González, Ana

    2012-01-01

    Enterococcus faecium MMRA is an enterocin A producer isolated from ‘Rayeb’, a Tunisian fermented milk drink. In this work, safety aspects and its behaviour in raw milk were investigated to assess its suitability as a protective adjunct culture. E. faecium MMRA showed interesting features such as the absence of several virulence traits, susceptibility to vancomycin and other clinically relevant antibiotics, and lack of haemolytic activity. To evaluate its performance as an adjunct culture for ...

  13. Enhanced bio-hydrogen production by the combination of dark- and photo-fermentation in batch culture.

    Science.gov (United States)

    Liu, Bing-Feng; Ren, Nan-Qi; Xie, Guo-Jun; Ding, Jie; Guo, Wan-Qian; Xing, De-Feng

    2010-07-01

    In this study, some key factors, for example, diluted ratio of effluents, the ratio of dark-photo bacteria, light intensity and light/dark cycle influencing hydrogen production by combining Clostridium butyricum and immobilized Rhodopseudomonas faecalis RLD-53 in batch culture, were investigated. Experimental results showed the photo-hydrogen yield decreased when increasing diluted ratio from 1:0.5 to 1:3, and it reached the maximum value of 4368 ml-H(2)/l-effluents at the ratio of 1:0.5. When the ratio of dark-photo bacteria was at 1:2, the hydrogen yield reached highest value of 4.946 mol-H(2)/mol-glucose and cumulative hydrogen volume was 5357 ml-H(2)/l-culture during the combination process. When the light intensity was at 10.25 W/m(2), the hydrogen volume of photo-fermentation and the combination process reached maximum value of 4260 ml-H(2)/l-effluents and 5892 ml-H(2)/l-culture, respectively. During the combination process, maximum total hydrogen yield was 5.374 mol-H(2)/mol-glucose. Meanwhile, hydrogen production under light/dark cycle was evaluated. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  14. Application of a slurry feeder to 1 and 3 stage continuous simultaneous saccharification and fermentation of dilute acid pretreated corn stover.

    Science.gov (United States)

    Brethauer, Simone; Studer, Michael H; Wyman, Charles E

    2014-10-01

    Continuous operation is often chosen for conceptual designs of biological processing of cellulosic biomass to ethanol to achieve higher volumetric productivities. Furthermore, continuous stirred tank reactors (CSTR) can handle higher solids concentrations than possible in batch mode due to broth thinning at partial conversion in a continuous fermentor. However, experience and literature data are very limited for continuous simultaneous saccharification and fermentation (cSSF) processes. In this work, a slurry feed system was developed and applied to a 3-stage bench-scale cSSF train to convert pretreated corn stover to ethanol and determine the effects of dilution rate and number of fermentation vessels on overall volumetric productivity. The highest productivity of 0.4gL(-1)h(-1) was achieved in a single cSSF vessel with an 8h residence time. Furthermore, productivity at identical total residence times was 12% higher for operation with 3 cSSF stages than for a single CSTR stage for pretreated corn stover. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Mechanism for multiplicity of steady states with distinct cell concentration in continuous culture of mammalian cells.

    Science.gov (United States)

    Yongky, Andrew; Lee, Jongchan; Le, Tung; Mulukutla, Bhanu Chandra; Daoutidis, Prodromos; Hu, Wei-Shou

    2015-07-01

    Continuous culture for the production of biopharmaceutical proteins offers the possibility of steady state operations and thus more consistent product quality and increased productivity. Under some conditions, multiplicity of steady states has been observed in continuous cultures of mammalian cells, wherein with the same dilution rate and feed nutrient composition, steady states with very different cell and product concentrations may be reached. At those different steady states, cells may exhibit a high glycolysis flux with high lactate production and low cell concentration, or a low glycolysis flux with low lactate and high cell concentration. These different steady states, with different cell concentration, also have different productivity. Developing a mechanistic understanding of the occurrence of steady state multiplicity and devising a strategy to steer the culture toward the desired steady state is critical. We establish a multi-scale kinetic model that integrates a mechanistic intracellular metabolic model and cell growth model in a continuous bioreactor. We show that steady state multiplicity exists in a range of dilution rate in continuous culture as a result of the bistable behavior in glycolysis. The insights from the model were used to devise strategies to guide the culture to the desired steady state in the multiple steady state region. The model provides a guideline principle in the design of continuous culture processes of mammalian cells. © 2015 Wiley Periodicals, Inc.

  16. Dichloromethane as the sole carbon source for an acetogenic mixed culture and isolation of a fermentative, dichloromethane-degrading bacterium.

    Science.gov (United States)

    Braus-Stromeyer, S A; Hermann, R; Cook, A M; Leisinger, T

    1993-01-01

    Dichloromethane (DCM) is utilized by the strictly anaerobic, acetogenic mixed culture DM as a sole source of carbon and energy for growth. Growth with DCM was linear, and cell suspensions of the culture degraded DCM with a specific activity of 0.47 mkat/kg of protein. A mass balance of 2 mol of chloride and 0.42 mol of acetate per mol of DCM was observed. The dehalogenation reaction showed similar specific activities under both anaerobic and aerobic conditions. Radioactivity from [14C]DCM in cell suspensions was recovered largely as 14CO2 (58%), [14C]acetate (23%), and [14C]formate (11%), which subsequently disappeared. This suggested that formate is a major intermediate in the pathway from DCM to acetate. Efforts to isolate from culture DM a pure culture capable of anaerobic growth with DCM were unsuccessful, although overall acetogenesis and the partial reactions are thermodynamically favorable. We then isolated bacterial strains DMA, a strictly anaerobic, gram-positive, endospore-forming rod, and DMB, a strictly anaerobic, gram-negative, endospore-forming homoacetogen, from culture DM. Both strain DMB and Methanospirillum hungatei utilized formate as a source of carbon and energy. Coculture of strain DMA with either M. hungatei or strain DMB in solid medium with DCM as the sole added source of carbon and energy was observed. These data support a tentative scheme for the acetogenic fermentation of DCM involving interspecies formate transfer from strain DMA to the acetogenic bacterium DMB or to the methanogen M. hungatei. Images PMID:8285685

  17. Isolation and characterization of halophilic lactic acid bacteria acting as a starter culture for sauce fermentation of the red alga Nori (Porphyra yezoensis).

    Science.gov (United States)

    Uchida, M; Miyoshi, T; Yoshida, G; Niwa, K; Mori, M; Wakabayashi, H

    2014-06-01

    A screening test was conducted for environmental samples to isolate halophilic lactic acid bacteria (HLAB) that can act as a starter in a Nori (Porphyra yezoensis)-sauce culture. After 9 months of incubation of enrichment cultures added with 25 kinds of environmental samples, growth of HLAB-like microorganisms was observed in six cultures salted at a 15% w/w level, including culture samples originally from mesopelagic water taken from 321 m-depth and from mountain snow taken at 2450 m-height. Ten strains were isolated and characterized as Tetragenococcus halophilus based on sequence analysis of the 16S rRNA gene. The isolates were inoculated into a newly prepared Nori-sauce culture and were confirmed to be able to act as a starter culture while three reference strains of T. halophilus obtained from a culture collection could not grow in the same culture. Halophilic lactic acid bacteria strains that can make growth in a highly salted Nori-sauce culture were isolated from environmental samples for the first time. All the isolates were identified as T. halophilus. The isolated strains are expected to be utilized as a starter culture for manufacturing fermented seaweed-sauce, which will be the first fermented food products obtained from algae. © 2014 The Society for Applied Microbiology.

  18. Continuous Ethanol Fermentation of Pretreated Lignocellulosic Biomasses, Waste Biomasses, Molasses and Syrup Using the Anaerobic, Thermophilic Bacterium Thermoanaerobacter italicus Pentocrobe 411.

    Directory of Open Access Journals (Sweden)

    Rasmus Lund Andersen

    Full Text Available Lignocellosic ethanol production is now at a stage where commercial or semi-commercial plants are coming online and, provided cost effective production can be achieved, lignocellulosic ethanol will become an important part of the world bio economy. However, challenges are still to be overcome throughout the process and particularly for the fermentation of the complex sugar mixtures resulting from the hydrolysis of hemicellulose. Here we describe the continuous fermentation of glucose, xylose and arabinose from non-detoxified pretreated wheat straw, birch, corn cob, sugar cane bagasse, cardboard, mixed bio waste, oil palm empty fruit bunch and frond, sugar cane syrup and sugar cane molasses using the anaerobic, thermophilic bacterium Thermoanaerobacter Pentocrobe 411. All fermentations resulted in close to maximum theoretical ethanol yields of 0.47-0.49 g/g (based on glucose, xylose, and arabinose, volumetric ethanol productivities of 1.2-2.7 g/L/h and a total sugar conversion of 90-99% including glucose, xylose and arabinose. The results solidify the potential of Thermoanaerobacter strains as candidates for lignocellulose bioconversion.

  19. Direct fermentation of L (+)-lactic acid from cassava pulp by solid state culture of Rhizopus oryzae.

    Science.gov (United States)

    Phrueksawan, Parichat; Kulpreecha, Songsri; Sooksai, Sarintip; Thongchul, Nuttha

    2012-10-01

    This study shows that Rhizopus oryzae is capable of directly utilizing cassava pulp alone to L-lactic acid in solid state fermentation (SSF). pH control at 6.0 helped prevent end product inhibition. Increasing lactate titer was observed at the higher initial moistened water due to the higher degree of substrate swelling and hydrolysis. With shaking, limited ethanol production but no change in lactate titer was observed. Rigorous shaking gave better oxygen transfer but presumably caused cell damage leading to substrate utilization through the biosynthesis route. Supplementing cassava pulp with nitrogen enhanced growth but not lactate production. Under the optimal conditions, R. oryzae converted the sole cassava pulp into lactic acid at the titer of 206.20 mg per g initial dry pulp. With the help of commercial cellulase and glucoamylase, the dramatically increasing lactate titer of 463.18 mg per g initial dry pulp was achieved via SSF.

  20. Microbial Ecophysiology of Whey Biomethanation: Comparison of Carbon Transformation Parameters, Species Composition, and Starter Culture Performance in Continuous Culture

    Science.gov (United States)

    Chartrain, M.; Bhatnagar, L.; Zeikus, J. G.

    1987-01-01

    Changes in lactose concentration and feed rate altered bacterial growth and population levels in a whey-processing chemostat. The bacterial population and methane production levels increased in relation to increased lactose concentrations comparable to those in raw whey (6%) and converted over 96% of the substrate to methane, carbon dioxide, and cells. Sequential increases in the chemostat dilution rate demonstrated excellent biomethanation performance at retention times as low as 25 h. Retention times shorter than 25 h caused prevalent bacterial populations and methane production to decrease, and intermediary carbon metabolites accumulated in the following order: acetate, butyrate, propionate, lactate, ethanol, and lactose. Bacterial species dominated in the chemostat as a function of their enhanced substrate uptake and growth kinetic properties. The substrate uptake kinetic properties displayed by the mixed chemostat population were equivalent to those of individual species measured in pure culture, whereas the growth kinetic properties of species in mixed culture were better than those measured in pure culture. A designed starter culture consisting of Leuconostoc mesenteroides, Desulfovibrio vulgaris, Methanosarcina barkeri, and Methanobacterium formicicum displayed biomethanation performance, which was similar to that of a diverse adapted mixed-culture inoculum, in a continuous contact digestor system to which 10 g of dry whey per liter was added. Preserved starter cultures were developed and used as inocula for the start-up of a continuous anaerobic digestion process that was effective for biomethanation of raw whey at a retention time of 100 h. Images PMID:16347341

  1. Impact of pre-selected autochthonous starter cultures on the flavor quality of Iberian dry-fermented "salchichón" sausage with different ripening processes.

    Science.gov (United States)

    Casquete, Rocío; Martín, Alberto; Benito, María José; Ruiz-Moyano, Santiago; Nevado, Francisco Pérez; Córdoba, María de Guía

    2011-01-01

    The purpose of this study was to investigate the impact on flavor quality of 2 autochthonous starter cultures in the manufacture of Iberian dry-fermented "sálchichón." A total of 2 strains of Pediococcus acidilactici (MS200 and MS198) were combined individually with a strain of Staphylococcus vitulus (RS34) to obtain 2 starter cultures: P200S34 and P198S34. The ability of both starter cultures to implant during 2 different manufacturing procedures of "salchichón" was evaluated by 16S rRNA gene sequence analysis. Changes due to starter culture inoculations on volatile compounds were determined by gas chromatography/mass spectrometry, and the impact on flavor quality evaluated by sensorial analysis. The implantation of starter cultures was adequate and did not significantly modify the flavor of the traditional Iberian dry-fermented "salchichón," while modulating the volatile compound profile with respect to that found in sausages with wild microbial populations. The influence of the starter cultures studied was more evident in the shorter sausage processing time. P198S34 was related with the increase in some volatile compounds deriving from lipid degradation. P200S34 contributed to the formation of several volatile compounds arising from lipid degradation, amino acid catabolism, and microbial esterase activity. P200S34 and P198S34 are autochthonous starter cultures for specific use in the processing of Iberian dry-fermented sausages. The application of these starters allows obtaining Iberian dry-fermented sausages with sensorial characteristics standardized. It is greatly interesting for processing and marketing industry of these high-quality meat products. © 2011 Institute of Food Technologists®

  2. Influence of ambient air temperature on the cooling/heating load of a single cell protein jacketed fermenter operating on cheese whey under continuous conditions.

    Science.gov (United States)

    Ghaly, A E; Mahmoud, N S

    2002-01-01

    The heat generated by mixing and lactose metabolism, during the continuous production of single cell protein from cheese whey lactose using a jacketed fermenter with running cooling water, was calculated using a heat balance equation. The technique quantified the heat produced in and lost from the fermentation unit. Most of the heat generated by mixing in the cell-free system (97.47%) was lost with exhaust gas, while a very small amount (2.53%) was lost through the fermenter lid, wall, and bottom. The heat generated by mixing was significant (26.31% of the total heat generated in the fermentation system with an active yeast population present) and, therefore, cannot be ignored in heat balance calculations. About 19.71% of the total heat generated in the reactor was lost through the coolant at an ambient temperature of 22 +/- 0.5 degrees C, showing the need for a cooling system. A yeast population size of 986 million cells/mL and a lactose removal efficiency of 95.6% were observed. About 72.5% and 27.5% of the lactose consumed were used for growth and respiration, respectively. A yield of 0.66 g of cells/g of lactose was achieved. The heat released by unit biomass was 7.05 kJ/g of cells. The results showed the significant impact of ambient air temperature on the cooling load. The heat to be removed from the medium by the cooling system varied from 3.46 to 281.56 kJ/h when the temperature increased from 16 to 30 degrees C. A heating system is needed to maintain the medium temperature at 34 degrees C when the ambient air temperature is below 16 degrees C.

  3. A systems biology approach to investigate the effect of pH-induced gene regulation on solvent production by Clostridium acetobutylicum in continuous culture

    Directory of Open Access Journals (Sweden)

    Bahl Hubert

    2011-01-01

    Full Text Available Abstract Background Clostridium acetobutylicum is an anaerobic bacterium which is known for its solvent-producing capabilities, namely regarding the bulk chemicals acetone and butanol, the latter being a highly efficient biofuel. For butanol production by C. acetobutylicum to be optimized and exploited on an industrial scale, the effect of pH-induced gene regulation on solvent production by C. acetobutylicum in continuous culture must be understood as fully as possible. Results We present an ordinary differential equation model combining the metabolic network governing solvent production with regulation at the genetic level of the enzymes required for this process. Parameterizing the model with experimental data from continuous culture, we demonstrate the influence of pH upon fermentation products: at high pH (pH 5.7 acids are the dominant product while at low pH (pH 4.5 this switches to solvents. Through steady-state analyses of the model we focus our investigations on how alteration in gene expression of C. acetobutylicum could be exploited to increase butanol yield in a continuous culture fermentation. Conclusions Incorporating gene regulation into the model of solvent production by C. acetobutylicum enables an accurate representation of the pH-induced switch to solvent production to be obtained and theoretical investigations of possible synthetic-biology approaches to be pursued. Steady-state analyses suggest that, to increase butanol yield, alterations in the expression of single solvent-associated genes are insufficient; a more complex approach targeting two or more genes is required.

  4. Dynamic model of temperature impact on cell viability and major product formation during fed-batch and continuous ethanolic fermentation in Saccharomyces cerevisiae.

    Science.gov (United States)

    Amillastre, Emilie; Aceves-Lara, César-Arturo; Uribelarrea, Jean-Louis; Alfenore, Sandrine; Guillouet, Stéphane E

    2012-08-01

    The impact of the temperature on an industrial yeast strain was investigated in very high ethanol performance fermentation fed-batch process within the range of 30-47 °C. As previously observed with a lab strain, decoupling between growth and glycerol formation occurred at temperature of 36 °C and higher. A dynamic model was proposed to describe the impact of the temperature on the total and viable biomass, ethanol and glycerol production. The model validation was implemented with experimental data sets from independent cultures under different temperatures, temperature variation profiles and cultivation modes. The proposed model fitted accurately the dynamic evolutions for products and biomass concentrations over a wide range of temperature profiles. R2 values were above 0.96 for ethanol and glycerol in most experiments. The best results were obtained at 37 °C in fed-batch and chemostat cultures. This dynamic model could be further used for optimizing and monitoring the ethanol fermentation at larger scale. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Quantification of viable bacterial starter cultures of Virgibacillus sp. and Tetragenococcus halophilus in fish sauce fermentation by real-time quantitative PCR.

    Science.gov (United States)

    Udomsil, Natteewan; Chen, Shu; Rodtong, Sureelak; Yongsawatdigul, Jirawat

    2016-08-01

    Real-time quantitative polymerase chain reaction (qPCR) methods were developed for the quantification of Virgibacillus sp. SK37 and Tetragenococcus halophilus MS33, which were added as starter cultures in fish sauce fermentation. The PCR assays were coupled with propidium monoazide (PMA) treatment of samples to selectively quantify viable cells and integrated with exogenous recombinant Escherichia coli cells to control variabilities in analysis procedures. The qPCR methods showed species-specificity for both Virgibacillus halodenitrificans and T. halophilus as evaluated using 6 reference strains and 28 strains of bacteria isolated from fish sauce fermentation. The qPCR efficiencies were 101.1% for V. halodenitrificans and 90.2% for T. halophilus. The quantification limits of the assays were 10(3) CFU/mL and 10(2) CFU/mL in fish sauce samples with linear correlations over 4 Logs for V. halodenitrificans and T. halophilus, respectively. The matrix effect was not observed when evaluated using fish sauce samples fermented for 1-6 months. The developed PMA-qPCR methods were successfully applied to monitor changes of Virgibacillus sp. SK37 and T. halophilus MS33 in a mackerel fish sauce fermentation model where culture-dependent techniques failed to quantify the starter cultures. The results demonstrated the usability of the methods as practical tools for monitoring the starter cultures in fish sauce fermentation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Fermentative and growth performances of Dekkera bruxellensis in different batch systems and the effect of initial low cell counts in co-cultures with Saccharomyces cerevisiae.

    Science.gov (United States)

    Meneghin, Maria Cristina; Bassi, Ana Paula Guarnieri; Codato, Carolina Brito; Reis, Vanda Renata; Ceccato-Antonini, Sandra Regina

    2013-08-01

    Dekkera bruxellensis is a multifaceted yeast present in the fermentative processes used for alcoholic beverage and fuel alcohol production - in the latter, normally regarded as a contaminant. We evaluated the fermentation and growth performance of a strain isolated from water in an alcohol-producing unit, in batch systems with/without cell recycling in pure and co-cultures with Saccharomyces cerevisiae. The ethanol resistance and aeration dependence for ethanol/acid production were verified. Ethanol had an effect on the growth of D. bruxellensis in that it lowered or inhibited growth depending on the concentration. Acid production was verified in agitated cultures either with glucose or sucrose, but more ethanol was produced with glucose in agitated cultures. Regardless of the batch system, low sugar consumption and alcohol production and expressive growth were found with D. bruxellensis. Despite a similar ethanol yield compared to S. cerevisiae in the batch system without cell recycling, ethanol productivity was approximately four times lower. However, with cell recycling, ethanol yield was almost half that of S. cerevisiae. At initial low cell counts of D. bruxellensis (10 and 1000 cells/ml) in co-cultures with S. cerevisiae, a decrease in fermentative efficiency and a substantial growth throughout the fermentative cycles were displayed by D. bruxellensis. Due to the peculiarity of cell repitching in Brazilian fermentation processes, D. bruxellensis is able to establish itself in the process, even when present in low numbers initially, substantially impairing bioethanol production due to the low ethanol productivity, in spite of comparable ethanol yields. Copyright © 2013 John Wiley & Sons, Ltd.

  7. Staphylococcus aureus in Continuous Culture: A Tool for the Rational Design of Antibiotic Treatment Protocols

    Science.gov (United States)

    Udekwu, Klas I.; Levin, Bruce R.

    2012-01-01

    In vitro measures of the pharmacodynamics of antibiotics that account for the factors anticipated for bacteria in infected patients are central to the rational design of antibiotic treatment protocols. We consider whether or not continuous culture devices are a way to obtain these measures. Staphylococcus aureus PS80 in high-density continuous cultures were exposed to oxacillin, ciprofloxacin, vancomycin, gentamicin, daptomycin and linezolid. Contrary to results from low density retentostats as well as to predictions of traditional PK/MIC ratios, daily dosing with up to 100× MIC did not clear these cultures. The densities of S. aureus in these cultures oscillated with constant amplitude and never fell below 105 CFU per ml. Save for daptomycin “treated” populations, the densities of bacteria in these cultures remained significantly below that of similar antibiotic-free cultures. Although these antibiotics varied in their pharmacodynamic properties there were only modest differences in their mean densities. Mathematical models and experiments suggest that the dominant factor preventing clearance was wall-adhering subpopulations reseeding the planktonic population which can be estimated and corrected for. Continuous cultures provide a way to evaluate the potential efficacy of antibiotic treatment regimes in vitro under conditions that are more clinically realistic and comprehensive than traditional in vitro PK/PD indices. PMID:22911681

  8. Staphylococcus aureus in continuous culture: a tool for the rational design of antibiotic treatment protocols.

    Science.gov (United States)

    Udekwu, Klas I; Levin, Bruce R

    2012-01-01

    In vitro measures of the pharmacodynamics of antibiotics that account for the factors anticipated for bacteria in infected patients are central to the rational design of antibiotic treatment protocols. We consider whether or not continuous culture devices are a way to obtain these measures. Staphylococcus aureus PS80 in high-density continuous cultures were exposed to oxacillin, ciprofloxacin, vancomycin, gentamicin, daptomycin and linezolid. Contrary to results from low density retentostats as well as to predictions of traditional PK/MIC ratios, daily dosing with up to 100× MIC did not clear these cultures. The densities of S. aureus in these cultures oscillated with constant amplitude and never fell below 10(5) CFU per ml. Save for daptomycin "treated" populations, the densities of bacteria in these cultures remained significantly below that of similar antibiotic-free cultures. Although these antibiotics varied in their pharmacodynamic properties there were only modest differences in their mean densities. Mathematical models and experiments suggest that the dominant factor preventing clearance was wall-adhering subpopulations reseeding the planktonic population which can be estimated and corrected for. Continuous cultures provide a way to evaluate the potential efficacy of antibiotic treatment regimes in vitro under conditions that are more clinically realistic and comprehensive than traditional in vitro PK/PD indices.

  9. Staphylococcus aureus in continuous culture: a tool for the rational design of antibiotic treatment protocols.

    Directory of Open Access Journals (Sweden)

    Klas I Udekwu

    Full Text Available In vitro measures of the pharmacodynamics of antibiotics that account for the factors anticipated for bacteria in infected patients are central to the rational design of antibiotic treatment protocols. We consider whether or not continuous culture devices are a way to obtain these measures. Staphylococcus aureus PS80 in high-density continuous cultures were exposed to oxacillin, ciprofloxacin, vancomycin, gentamicin, daptomycin and linezolid. Contrary to results from low density retentostats as well as to predictions of traditional PK/MIC ratios, daily dosing with up to 100× MIC did not clear these cultures. The densities of S. aureus in these cultures oscillated with constant amplitude and never fell below 10(5 CFU per ml. Save for daptomycin "treated" populations, the densities of bacteria in these cultures remained significantly below that of similar antibiotic-free cultures. Although these antibiotics varied in their pharmacodynamic properties there were only modest differences in their mean densities. Mathematical models and experiments suggest that the dominant factor preventing clearance was wall-adhering subpopulations reseeding the planktonic population which can be estimated and corrected for. Continuous cultures provide a way to evaluate the potential efficacy of antibiotic treatment regimes in vitro under conditions that are more clinically realistic and comprehensive than traditional in vitro PK/PD indices.

  10. Influence of Starter Cultures, Fermentation Techniques, and Acetic Acid on the Volatile Aroma and Sensory Profile of Cocoa Liquor and Chocolate

    DEFF Research Database (Denmark)

    Crafack, Michael

    the principal raw material for chocolate production, good quality cocoa beans are in high demand on the World market as a prerequisite for the production of high quality chocolates and other confectionary products. To produce good quality cocoa suitable for chocolate production, it is essential that the beans...... properties. With the object ive of improving the volatile aroma and sensory properties of Ghanaian Forastero cocoa, the present Ph.D. study investigates the use of two defined mixed starter cultures encompassing strains of Acetobacter pasteurianus and Lactobacillus fermentum in combination with either...... and tray fermented samples, aroma analysis of the roasted cocoa liquors showed great variation between the incubated and conventionally fermented samples. While the fermented samples displayed the most diverse composition of volatile compounds, the incubated samples completely lacked essential cocoa aroma...

  11. The pentose moiety of adenosine and inosine is an important energy source for the fermented-meat starter culture Lactobacillus sakei CTC 494.

    Science.gov (United States)

    Rimaux, T; Vrancken, G; Vuylsteke, B; De Vuyst, L; Leroy, F

    2011-09-01

    The genome sequence of Lactobacillus sakei 23K has revealed that the species L. sakei harbors several genes involved in the catabolism of energy sources other than glucose in meat, such as glycerol, arginine, and nucleosides. In this study, a screening of 15 L. sakei strains revealed that arginine, inosine, and adenosine could be used as energy sources by all strains. However, no glycerol catabolism occurred in any of the L. sakei strains tested. A detailed kinetic analysis of inosine and adenosine catabolism in the presence of arginine by L. sakei CTC 494, a fermented-meat starter culture, was performed. It showed that nucleoside catabolism occurred as a mixed-acid fermentation in a pH range (pH 5.0 to 6.5) relevant for sausage fermentation. This resulted in the production of a mixture of acetic acid, formic acid, and ethanol from ribose, while the nucleobase (hypoxanthine and adenine in the case of fermentations with inosine and adenosine, respectively) was excreted into the medium stoichiometrically. This indicates that adenosine deaminase activity did not take place. The ratios of the different fermentation end products did not vary with environmental pH, except for the fermentation with inosine at pH 5.0, where lactic acid was produced too. In all cases, no other carbon-containing metabolites were found; carbon dioxide was derived only from arginine catabolism. Arginine was cometabolized in all cases and resulted in the production of both citrulline and ornithine. Based on these results, a pathway for inosine and adenosine catabolism in L. sakei CTC 494 was presented, whereby both nucleosides are directly converted into their nucleobase and ribose, the latter entering the heterolactate pathway. The present study revealed that the pentose moiety (ribose) of the nucleosides inosine and adenosine is an effective fermentable substrate for L. sakei. Thus, the ability to use these energy sources offers a competitive advantage for this species in a meat environment.

  12. The Pentose Moiety of Adenosine and Inosine Is an Important Energy Source for the Fermented-Meat Starter Culture Lactobacillus sakei CTC 494▿

    Science.gov (United States)

    Rimaux, T.; Vrancken, G.; Vuylsteke, B.; De Vuyst, L.; Leroy, F.

    2011-01-01

    The genome sequence of Lactobacillus sakei 23K has revealed that the species L. sakei harbors several genes involved in the catabolism of energy sources other than glucose in meat, such as glycerol, arginine, and nucleosides. In this study, a screening of 15 L. sakei strains revealed that arginine, inosine, and adenosine could be used as energy sources by all strains. However, no glycerol catabolism occurred in any of the L. sakei strains tested. A detailed kinetic analysis of inosine and adenosine catabolism in the presence of arginine by L. sakei CTC 494, a fermented-meat starter culture, was performed. It showed that nucleoside catabolism occurred as a mixed-acid fermentation in a pH range (pH 5.0 to 6.5) relevant for sausage fermentation. This resulted in the production of a mixture of acetic acid, formic acid, and ethanol from ribose, while the nucleobase (hypoxanthine and adenine in the case of fermentations with inosine and adenosine, respectively) was excreted into the medium stoichiometrically. This indicates that adenosine deaminase activity did not take place. The ratios of the different fermentation end products did not vary with environmental pH, except for the fermentation with inosine at pH 5.0, where lactic acid was produced too. In all cases, no other carbon-containing metabolites were found; carbon dioxide was derived only from arginine catabolism. Arginine was cometabolized in all cases and resulted in the production of both citrulline and ornithine. Based on these results, a pathway for inosine and adenosine catabolism in L. sakei CTC 494 was presented, whereby both nucleosides are directly converted into their nucleobase and ribose, the latter entering the heterolactate pathway. The present study revealed that the pentose moiety (ribose) of the nucleosides inosine and adenosine is an effective fermentable substrate for L. sakei. Thus, the ability to use these energy sources offers a competitive advantage for this species in a meat environment

  13. Preparation of glycerol-enriched yeast culture and its effect on blood metabolites and ruminal fermentation in goats.

    Science.gov (United States)

    Ye, Gengping; Zhu, Yongxing; Liu, Jin; Chen, Xingxiang; Huang, Kehe

    2014-01-01

    The aim of this study was to isolate a glycerol-producing yeast strain from nature to prepare glycerol-enriched yeast culture (GY), and preliminarily evaluate the effects of GY on blood metabolites and ruminal fermentation in goats. During the trial, six isolates were isolated from unprocessed honey, and only two isolates with higher glycerol yield were identified by analysis of 26S ribosomal DNA sequences. One of the two isolates was identified as Saccharomyces cerevisiae, a direct-fed microbe permitted by the FDA. This isolate was used to prepare GY. The fermentation parameters were optimized through single-factor and orthogonal design methods to maximize the glycerol yield and biomass. The final GY contained 38.7±0.6 g/L glycerol and 12.6±0.5 g/L biomass. In vivo, eight castrated male goats with ruminal fistula were used in a replicated 4×4 Latin square experiment with four consecutive periods of 15 d. Treatments were as follows: control, LGY, MGY, and HGY with 0, 100, 200, and 300 mL GY per goat per day, respectively. The GY was added in two equal portions at 08∶00 and 17∶00 through ruminal fistula. Samples of blood and ruminal fluid were collected on the last one and two days of each period, respectively. Results showed that the plasma concentrations of triglyceride and total cholesterol were not affected by the supplemented GY. Compared with the control, goats supplemented with MGY and HGY had significantly higher (P<0.05) concentrations of plasma glucose and total protein, ruminal volatile fatty acid and molar proportion of propionate, and significantly lower (P<0.05) ruminal pH and ammonia nitrogen. These parameters changed linearly with increasing GY supplementation level (P<0.05). In conclusion, GY has great potential to be developed as a feed additive with dual effects of glycerol and yeast for ruminants.

  14. Culture-independent bacterial community analysis of the salty-fermented fish paste products of Thailand and Laos.

    Science.gov (United States)

    Marui, Junichiro; Boulom, Sayvisene; Panthavee, Wanchai; Momma, Mari; Kusumoto, Ken-Ichi; Nakahara, Kazuhiko; Saito, Masayoshi

    2015-01-01

    A bacterial community analysis, using a culture-independent method (polymerase chain reaction-denaturing gradient gel electrophoresis), detected 17 species of bacteria including species of the genera Tetragenococcus, Lactobacillus, Pediococcus, Weissella Halanaerobium, Clostridium, and Sphingomonas in a traditional salty-fermented fish paste known as pla-ra or pa-daek in Thailand and Laos, which is used as a storage-stable multi-purpose seasoning. The representative genus of lactic acid bacteria seemed to vary in the 10 products collected from Thailand and Laos. Tetragenococci were common in products from central Thailand and Vientiane in Laos which had salinities of not less than 11% and pH values ranging from 5.6 to 6.1. However, lactobacilli were common in products from northern Thailand which had the lowest salinities (8.3-8.6%) and pH values (4.5-4.8) of all the samples examined. Two Lactobacillus and one Tetragenococcus species were detected in one product from northeastern Thailand containing 10% salt. These results suggest that salinity in pla-ra/pa-daek is an important determinant of the representative genus of lactic acid bacteria such as, Tetragenococcus or Lactobacillus. Additionally, differences in the acidity between these two groups seemed to be related to the production of d-/l-lactic acid in the lactic acid bacteria in each product. This is the first study to report a correlation between bacterial community structure and taste components in pla-ra/pa-daek products from various regions. This scientific work on a traditional fermented food will be useful in helping local producers meet differing consumer preferences in various regions.

  15. Preparation of glycerol-enriched yeast culture and its effect on blood metabolites and ruminal fermentation in goats.

    Directory of Open Access Journals (Sweden)

    Gengping Ye

    Full Text Available The aim of this study was to isolate a glycerol-producing yeast strain from nature to prepare glycerol-enriched yeast culture (GY, and preliminarily evaluate the effects of GY on blood metabolites and ruminal fermentation in goats. During the trial, six isolates were isolated from unprocessed honey, and only two isolates with higher glycerol yield were identified by analysis of 26S ribosomal DNA sequences. One of the two isolates was identified as Saccharomyces cerevisiae, a direct-fed microbe permitted by the FDA. This isolate was used to prepare GY. The fermentation parameters were optimized through single-factor and orthogonal design methods to maximize the glycerol yield and biomass. The final GY contained 38.7±0.6 g/L glycerol and 12.6±0.5 g/L biomass. In vivo, eight castrated male goats with ruminal fistula were used in a replicated 4×4 Latin square experiment with four consecutive periods of 15 d. Treatments were as follows: control, LGY, MGY, and HGY with 0, 100, 200, and 300 mL GY per goat per day, respectively. The GY was added in two equal portions at 08∶00 and 17∶00 through ruminal fistula. Samples of blood and ruminal fluid were collected on the last one and two days of each period, respectively. Results showed that the plasma concentrations of triglyceride and total cholesterol were not affected by the supplemented GY. Compared with the control, goats supplemented with MGY and HGY had significantly higher (P<0.05 concentrations of plasma glucose and total protein, ruminal volatile fatty acid and molar proportion of propionate, and significantly lower (P<0.05 ruminal pH and ammonia nitrogen. These parameters changed linearly with increasing GY supplementation level (P<0.05. In conclusion, GY has great potential to be developed as a feed additive with dual effects of glycerol and yeast for ruminants.

  16. Enhanced Anti-Obesity Activities of Red Mold Dioscorea When Fermented Using Deep Ocean Water as the Culture Water

    Directory of Open Access Journals (Sweden)

    Tzu-Ming Pan

    2013-10-01

    Full Text Available Deep ocean water (DOW has, in previous studies, been found to be a novel anti-obesity drink and useful in raising Monascus-produced monascin and ankaflavin levels. This may resolve the limited anti-obesity ability of red mold dioscorea (RMD known as the Monascus purpureus-fermented Disocorea batatas. This study aims to compare the anti-obesity effect of DOW-cultured RMD (DOW-RMD and ultra-pure water-cultured RMD (UPW-RMD in rats fed on a high fat diet. Moreover, the effect of ions composition of DOW and DOW-influenced functional metabolites change of RMD on the differentiation and lipogenesis regulation were investigated using 3T3-L1 pre-adipocytes. In the animal test, compared to UPW-RMD, DOW-RMD possessed better ability to inhibit increases in weight gain, and better feed efficiency, body-fat pad and cross-sectional area of adipocytes. In the cell test, the anti-obesity abilities of DOW-RMD in inhibiting PPARγ and C/EBPα expression in differentiation and lipoprotein lipase activity in lipogenesis were contributed to by the DOW-increased monascin and ankaflavin levels and the ions of DOW, respectively.

  17. Concomitant biohydrogen and poly-β-hydroxybutyrate production from dark fermentation effluents by adapted Rhodobacter sphaeroides and mixed photofermentative cultures.

    Science.gov (United States)

    Ghimire, Anish; Valentino, Serena; Frunzo, Luigi; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

    2016-10-01

    This work aimed at investigating concomitant production of biohydrogen and poly-β-hydroxybutyrate (PHB) by photofermentation (PF) using dark fermentation effluents (DFE). An adapted culture of Rhodobacter sphaeroides AV1b (pH 6.5, 24±2°C) achieved H2 and PHB yields of 256 (±2) NmLH2/g Chemical Oxygen Demand (COD) and 273.8mgPHB/gCOD (32.5±3% of the dry cells weight (DCW)), respectively. When a diluted (1:2) DFE medium was applied to the adapted pure and mixed photofermentative culture, the respective H2 yields were 164.0 (±12) and 71.3 (±6) NmLH2/gCOD and the PHB yields were 212.1 (±105.2) and 50.7 (±2.7) mgPHB/gCOD added, corresponding to 24 (±0.7) and 6.3 (±0) % DCW, respectively. The concomitant H2 and PHB production from the PF process gave a good DFE post treatment achieving up to 80% COD removal from the initial DFE. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Quality determination of vegetable oils used as an addition to fermented meat products with different starter cultures

    Directory of Open Access Journals (Sweden)

    Hana Šulcerová

    2017-01-01

    Full Text Available There were developed samples of fermented meat products of „Mettwurst" with an addition of a starter culture pentosacceus AS-3/100 or probiotic culture Lactobacillus casei Lc-01 and its combinations for this thesis. A part of animal fat was replaced with vegetable oils - sunflower oil and rapeseed oil. For comparison, there was also used a sample without an addition of vegetable oil. There were determined the characteristics of fats in samples: saponification value, acidity value, esteric, iodine and peroxide value. The samples were determined on the day of production and always once a week in a period of three following weeks. Every single sample was hereby determined 3 times. According to the results, it is more advantageous to use the samples with sunflower oil with an addition of specific cultures Lactobacillus casei Lc-01 and Pediococcus pentosaceus AS-3/100. The saponification value when adding sunflower oil detects that the quality of fat remains stable till the 14th day of storage (p <0.05. The comparison of acid value detects that a sample with sunflower oil and culture Pediococcus pentosaceus AS-3/100 is more advantageous due to fast acidification in the first half of storage period. Good results of iodine and peroxide value had the variation of a sample with sunflower oil and a combination of both cultures. The variation of peroxide value maintained the lowest values. By using the samples with sunflower oil and unispecific cultures L. casei Lc-01 and P. pentosaceus AS-3/100, the culture P. pentosaceus AS-3/100, which remained stable till the 14th day of production, reached the best values of peroxide value. The sunflower oil is in spite of high content of PUFA more stable to which also contributes the increased content of vitamin E that works as an antioxidant here. The disadvantage of rapeseed oil is its higher susceptibility to oxidation. For reasons of faster decomposition of vegetable oils would be essential to cut down on the

  19. Kinetic Analysis of Strains of Lactic Acid Bacteria and Acetic Acid Bacteria in Cocoa Pulp Simulation Media toward Development of a Starter Culture for Cocoa Bean Fermentation

    Science.gov (United States)

    Lefeber, Timothy; Janssens, Maarten; Camu, Nicholas; De Vuyst, Luc

    2010-01-01

    The composition of cocoa pulp simulation media (PSM) was optimized with species-specific strains of lactic acid bacteria (PSM-LAB) and acetic acid bacteria (PSM-AAB). Also, laboratory fermentations were carried out in PSM to investigate growth and metabolite production of strains of Lactobacillus plantarum and Lactobacillus fermentum and of Acetobacter pasteurianus isolated from Ghanaian cocoa bean heap fermentations, in view of the development of a defined starter culture. In a first step, a selection of strains was made out of a pool of strains of these LAB and AAB species, obtained from previous studies, based on their fermentation kinetics in PSM. Also, various concentrations of citric acid in the presence of glucose and/or fructose (PSM-LAB) and of lactic acid in the presence of ethanol (PSM-AAB) were tested. These data could explain the competitiveness of particular cocoa-specific strains, namely, L. plantarum 80 (homolactic and acid tolerant), L. fermentum 222 (heterolactic, citric acid fermenting, mannitol producing, and less acid tolerant), and A. pasteurianus 386B (ethanol and lactic acid oxidizing, acetic acid overoxidizing, acid tolerant, and moderately heat tolerant), during the natural cocoa bean fermentation process. For instance, it turned out that the capacity to use citric acid, which was exhibited by L. fermentum 222, is of the utmost importance. Also, the formation of mannitol was dependent not only on the LAB strain but also on environmental conditions. A mixture of L. plantarum 80, L. fermentum 222, and A. pasteurianus 386B can now be considered a mixed-strain starter culture for better controlled and more reliable cocoa bean fermentation processes. PMID:20889778

  20. Interesting Starter Culture Strains for Controlled Cocoa Bean Fermentation Revealed by Simulated Cocoa Pulp Fermentations of Cocoa-Specific Lactic Acid Bacteria ▿

    Science.gov (United States)

    Lefeber, Timothy; Janssens, Maarten; Moens, Frédéric; Gobert, William; De Vuyst, Luc

    2011-01-01

    Among various lactic acid bacterial strains tested, cocoa-specific strains of Lactobacillus fermentum were best adapted to the cocoa pulp ecosystem. They fermented glucose to lactic acid and acetic acid, reduced fructose to mannitol, and converted citric acid into lactic acid and 2,3-butanediol. PMID:21803901

  1. Hydrogen production by Hup{sup -} mutant and wild type strains of Rhodobacter capsulatus on dark fermenter effluent of sugar beet thick juice in batch and continuous photobioreactors

    Energy Technology Data Exchange (ETDEWEB)

    Oezguer, Ebru [Middle East Technical Univ., Ankara (Turkey). Dept. of Chemical Engineering; Uyar, Basar [Kocaeli Univ. (Turkey). Dept. of Chemical Engineering; Guergan, Muazzez; Yuecel, Meral [Middle East Technical Univ., Ankara (Turkey). Dept. of Biology

    2010-07-01

    The HYVOLUTION project (EU 6th frame) is aimed to develop an integrated process in which biomass is fermented to acetate, lactate, CO{sub 2} and hydrogen followed by photofermentation of acetate and lactate to hydrogen and CO{sub 2} with photosynthetic purple nonsulfur bacteria (PNS bacteria). Growth and hydrogen production of Rhodobacter capsulatus was investigated on the dark fermenter effluent of thick juice (processed raw sugar beet juice) which contained acetate and NH{sub 4}Cl. In this effluent media, the hydrogen production of wild type bacterium and an uptake-hydrogenase deficient mutant (hup-) were compared in small scale (55 ml) batch and large scale (4 L) continuous photobioreactors in indoor conditions under constant illumination of 2000 lux. In continuous operation mode, the overall hydrogen production yields were 1.84 and 1.92 mol H{sub 2}/mol acetate, the maximum hydrogen productivities were 1.29 and 0.89 mmol H{sub 2}/L.h, for the wild type and mutant strains, respectively. On the other hand, in batch operation mode, the overall hydrogen production yields were 1.25 and 1.44 mol H{sub 2}/mol acetate, the maximum hydrogen productivities were 0.28 and 0.52 mmol H{sub 2}/L.h, for the wild type and mutant strains, respectively. The results show that Rhodobacter capsulatus is capable of using sugar beet thick juice effluent as substrate for hydrogen production; which makes it a suitable bacterium to be employed in integrated termophilic fermentation-photofermentation process. (orig.)

  2. The effect of tea fermentation on rosmarinic acid and antioxidant properties using selected in vitro sprout culture of Orthosiphon aristatus as a model study.

    Science.gov (United States)

    Hunaefi, Dase; Smetanska, Iryna

    2013-12-01

    Orthosiphon aristatus, an Indonesian medicinal plant, is normally used as a traditional herbal tea. Recently, this plant has begun to attract attention due to its antioxidant properties. However, little is known about tea fermentation effect on antioxidant properties of this plant. Thus, to extend the tea fermentation study, in vitro sprout culture of this plant was established as a new feature model. This model plant was selected based on three reasons. Firstly, as a native tropical plant, to grow this plant in sub-tropic area is considered difficult. Secondly, the in vitro sprout culture is more genetically stable compared to other types of in vitro cultures. Thirdly, results showed that this in vitro sprout culture grew faster and produced higher biomass than in vitro tissue culture. Both characteristics are important in producing tea leaves. Accordingly, the aim of the current study was twofold. First was to establish high rosmarinic acid line of in vitro sprout culture of Orthosiphon aristatus by elicitation. Second was to evaluate the effect of tea fermentation on antioxidant properties of this plant. Results showed that yeast extract (5 g/L) elicitation resulted in the highest production of rosmarinic acid. This elicited plant was subjected to partial and full tea fermentation. Results revealed that both tea fermentations decreased the level of rosmarinic acid, total phenolic compounds, flavonoids, and flavonols. These decreases were concomitant with reduced antioxidant activities as measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, Trolox equivalent antioxidant capacity (TEAC), and Superoxide dismutase (SOD)-like activity assays. HPLC results showed that the longer the tea fermentation was, the greater reduction rosmarinic acid was found. High correlation value of 0.922 between rosmarinic acid and antioxidant activities was also observed. These results indicated that rosmarinic acid is the major contributor to the antioxidant activities

  3. Cell-to-cell contact and antimicrobial peptides play a combined role in the death of Lachanchea thermotolerans during mixed-culture alcoholic fermentation with Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Kemsawasd, Varongsiri; Branco, Patrícia; Almeida, Maria Gabriela

    2015-01-01

    The roles of cell-to-cell contact and antimicrobial peptides in the early death of Lachanchea thermotolerans CBS2803 during anaerobic, mixed-culture fermentations with Saccharomyces cerevisiae S101 were investigated using a commercially available, double-compartment fermentation system separated ...

  4. Monitoring of changes in lactic acid bacteria during production of Thai traditional fermented shrimp (Kung-Som by culturing method and PCR-DGGE technique

    Directory of Open Access Journals (Sweden)

    Kanokwan Thongruck

    2017-02-01

    Full Text Available The lactic acid bacteria (LAB ecology of Kung-Som, a traditional Thai fermented shrimp, was investigated using culture-dependent and culture-independent methods. Kung-Som was fermented at room temperature under anaerobic condition for 7 days using autochthonous fermentation. The viable counts revealed a dominance of LAB, from the 16S rRNA gene V6-V8 sequence analysis of the isolates, Enterococcus faecalis, Enterococcus sanguinicola, Weissella cibaria, Weissella confusa, Enterococcus sp., Leuconostoc pseudomesenteroides and Lactobacillus plantarum were observed. The total microbial community was profiled without cultivation by analyzing the DNA that was directly extracted from the Kung-Som samples. The 16S rRNA gene V6-V8 regions were used as targets in the denaturing gradient gel electrophoresis (DGGE, profiling of the LAB. Pediococcus argentinicus, Lactococcus lactis subsp. lactis, Lactococcus garvieae, Lactobacillus curvatus, Lactobacillus sakei and Lact. plantarum were observed. Our results provide evidence of the necessity to combine the two methods for better description of microbial communities in Kung-Som fermentation.

  5. Essential oils have different effects on human pathogenic and commensal bacteria in mixed faecal fermentations compared with pure cultures.

    Science.gov (United States)

    Thapa, Dinesh; Louis, Petra; Losa, Riccardo; Zweifel, Béatrice; Wallace, R John

    2015-02-01

    A static batch culture system inoculated with human faeces was used to determine the influence of essential oil compounds (EOCs) on mixed faecal microbiota. Bacteria were quantified using quantitative PCR of 16S rRNA genes. Incubation for 24 h of diluted faeces from six individuals caused enrichment of Bifidobacterium spp., but proportions of other major groups were unaffected. Thymol and geraniol at 500 p.p.m. suppressed total bacteria, resulting in minimal fermentation. Thymol at 100 p.p.m. had no effect, nor did eugenol or nerolidol at 100 or 500 p.p.m. except for a slight suppression of Eubacterium hallii. Methyl isoeugenol at 100 or 500 p.p.m. suppressed the growth of total bacteria, accompanied by a large fall in the molar proportion of propionate formed. The relative abundance of Faecalibacterium prausnitzii was unaffected except with thymol at 500 p.p.m. The ability of EOCs to control numbers of the pathogen Clostridium difficile was investigated in a separate experiment, in which the faecal suspensions were amended by the addition of pure culture of C. difficile. Numbers of C. difficile were suppressed by thymol and methyl isoeugenol at 500 p.p.m. and to a lesser extent at 100 p.p.m. Eugenol and geraniol gave rather similar suppression of C. difficile numbers at both 100 and 500 p.p.m. Nerolidol had no significant effect. It was concluded from these and previous pure-culture experiments that thymol and geraniol at around 100 p.p.m. could be effective in suppressing pathogens in the small intestine, with no concern for beneficial commensal colonic bacteria in the distal gut. © 2015 The Authors.

  6. Bioethanol production from sweet potato (Ipomoea batatas L. flour using co-culture of Trichoderma sp. and Saccharomyces cerevisiae in solid-state fermentation

    Directory of Open Access Journals (Sweden)

    Manas Ranjan Swain

    2013-04-01

    Full Text Available The aim of this work was to study the optimiation of co-culturing of Trichoderma sp. and Saccharomyces cerevisiae (1:4 ratio on sweet potato (Ipomoea batatas L. flour (SPF for the production of bio-ethanol in solid-state fermentation (SSF. Maximum ethanol (172 g/kg substrate was produced in a medium containing 80% moisture, ammonium sulphate 0.2%, pH 5.0, inoculuted with 10% inoculum size and fermented at 30ºC for 72h. .Concomitant with highest ethanol concentration, maximum ethanol productivity (2.8 g/kg substrate/h, microbial biomass (23×10(8 CFU/ g substrate, ethanol yield (47 g/100g sugar consumed and fermentation efficiency (72% were also obtained under these conditions. Cell interaction was observed familiar between the viable cells of Trichoderma sp. and S. cerevisiae when co-cultured. Ethanol production ability by the co-culture was 65 % higher than the single culture of S. cerevisiae from un-saccharified SPF.

  7. Optimization of cultural conditions for biosurfactant production by Pleurotus djamor in solid state fermentation.

    Science.gov (United States)

    Velioglu, Zulfiye; Ozturk Urek, Raziye

    2015-11-01

    Being eco-friendly, less toxic, more biodegradable and biocompatible, biological surfactants have higher activity and stability compared to synthetic ones. In spite of the fact that there are abundant benefits of biosurfactants over the synthetic congeners, the problem related with the economical and large scale production proceeds. The utilization of several industrial wastes in the production media as substrates reduces the production cost. This current study aims optimization of biosurfactant production conditions by Pleurotus djamor, grown on sunflower seed shell, grape wastes or potato peels as renewable cheap substrates in solid state fermentation. After determination of the best substrate for biosurfactant production, we indicate optimum size and amount of solid substrate, volume of medium, temperature, pH and Fe(2+) concentrations on biosurfactant production. In optimum conditions, by reducing water surface tension to 28.82 ± 0.3 mN/m and having oil displacement diameter of 3.9 ± 0.3 cm, 10.205 ± 0.5 g/l biosurfactant was produced. Moreover, chemical composition of biosurfactant produced in optimum condition was determined by FTIR. Lastly, laboratory's large-scale production was carried out in optimum conditions in a tray bioreactor designed by us and 8.9 ± 0.5 g/l biosurfactant was produced with a significant surface activity (37.74 ± 0.3 mN/m). With its economical suggestions and applicability of laboratory's large-scale production, this work indicates the possibility of using low cost agro-industrial wastes as renewable substrates for biosurfactant production. Therefore, using economically produced biosurfactant will reduce cost in several applications such as bioremediation, oil recovery and biodegradation of toxic chemicals. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  8. Fermentation of Isolated Pectin and Pectin from Intact Forages by Pure Cultures of Rumen Bacteria1

    Science.gov (United States)

    Gradel, Catherine M.; Dehority, B. A.

    1972-01-01

    Studies on the rate and extent of galacturonic acid and isolated pectin digestion were carried out with nine strains of rumen bacteria (Butyrivibrio fibrisolvens H10b and D16f, Bacteroides ruminicola 23 and D31d, Lachnospira multiparus D15d, Peptostreptococcus sp. D43e, B. succinogenes A3c, Ruminococcus flavefaciens B34b, and R. albus 7). Only three strains, 23, D16f, and D31d, utilized galacturonic acid as a sole energy source, whereas all strains except A3c and H10b degraded (solubilized) and utilized purified pectin. Nutrient composition of the basal medium and separate sterilization of the substrate affected the rate and extent of fermentation for both substrates. Pectin degradation and utilization were measured with two maturity stages each of intact bromegrass and alfalfa. For bromegrass I, all strains tested (B34b, 23, D16f, D31d, D15d, and D43e) degraded a considerable amount of pectin and, with the exception of B34b, utilized most of what was degraded. Similar, but lower, results were obtained with bromegrass II, except for the two strains of B. ruminicola, 23 and D31d, which were unable to degrade and utilize pectin from this forage. All strains were able to degrade and utilize pectin from both maturity stages of alfalfa; however, values were considerably lower for strains 23 and D31d. Synergism studies, in which a limited utilizing strain, B34b, was combined with the limited degrading strain, D31d, resulted in a slight increase in degradation and a very marked increase in utilization of the pectin in all four forages. Similar results were obtained on both alfalfa substrates with a combination of strains B34b and D16f; however, no increases were observed with this combination on bromegrass. PMID:4552890

  9. Xylose fermentation to biofuels (hydrogen and ethanol) by extreme thermophilic (70 C) mixed culture

    DEFF Research Database (Denmark)

    Chenxi, Zhao; Karakashev, Dimitar Borisov; Lu, W.

    2010-01-01

    Combined biohydrogen and bioethanol (CHE) production from xylose was achieved by an extreme thermophilic (70 degrees C) mixed culture. Effect of initial pH, xylose, peptone, FeSO4, NaHCO3, yeast extract, trace mineral salts, vitamins, and phosphate buffer concentrations on bioethanol and biohydro...

  10. Mixed Cultures Fermentation for the Production of Poly-ß-hydroxybutyrate

    Directory of Open Access Journals (Sweden)

    Thomas Shalin

    2014-10-01

    Full Text Available Poly-ß-hydroxybutyrate (PHB is a biodegradable intracellular microbial product produced by many bacteria and it is comparable to some of the petrochemical derived thermoplastics such as polypropylene. One of the main barriers for the commercial exploitation is the high cost of the substrate for the production of biopolymer. The utilization of mixed microbial cultures facilitates the use of complex substrates thereby reducing the cost of PHB production. In the present study, mixed culture systems were evaluated for PHB production. Bacillus firmus NII 0830 was used for the production of PHB since it accumulates a large amount of PHB and a second organism Lactobacillus delbrueckii NII 0925 was used to provide lactic acid. FTIR and 1H NMR analyses revealed that the PHB extracted from pure culture and mixed culture showed exact match to that of standard PHB. Biodegradation studies of the PHB blends showed 87% degradation. It was also found that a consortium of organisms degraded the films faster than a single organism.

  11. The dominant microbial community associated with fermentation of Obushera (sorghum and millet beverages) determined by culture-dependent and culture-independent methods.

    Science.gov (United States)

    Mukisa, Ivan M; Porcellato, Davide; Byaruhanga, Yusuf B; Muyanja, Charles M B K; Rudi, Knut; Langsrud, Thor; Narvhus, Judith A

    2012-11-01

    Obushera includes four fermented cereal beverages from Uganda namely: Obutoko, Enturire, Ekitiribita and Obuteire, whose microbial diversity has not hitherto been fully investigated. Knowledge of the microbial diversity and dynamics in these products is crucial for understanding their safety and development of appropriate starter cultures for controlled industrial processing. Culture-dependent and culture-independent techniques including denaturating gradient gel electrophoresis (DGGE) and mixed DNA sequencing of polymerase chain reaction (PCR) amplified ribosomal RNA genes were used to study the bacteria and yeast diversity of Obushera. The pH dropped from 6.0-4.6 to 3.5-4.0 within 1-2 days for Obutoko, Enturire and Obuteire whereas that of Ekitiribita decreased to 4.4 after 4 days. Counts of lactic acid bacteria (LAB) increased from 5.0 to 11.0 log cfug(-1) and yeasts increased from 3.4 to 7.1 log cfug(-1) while coliform counts decreased from 2.0 to analysis. LAB isolates included: Enterococcus spp., Lactobacillus (Lb.) plantarum, Lb. fermentum, Lb. delbrueckii, Lactococcus lactis, Leuconostoc lactis, Streptococcus (S.) infantarius subsp. infantarius, Pediococcus pentosaceus and Weisella (W.) confusa. DGGE indicated predominance of S. gallolyticus, S. infantarius subsp. infantarius, Lb. fermentum, Lb. delbrueckii, W. confusa, Lb. reuteri, Fructobacillus spp., L. lactis and L. lactis. Yeast isolates included Clavispora lusitaniae, Cyberlindnera fabianii, Issatchenkia orientalis and Saccharomyces cerevisiae. DGGE indicated predominance of S. cerevisiae in Obutoko, Enturire and Obuteire and also detected Pichia spp. and I. orientalis in Obutoko. Obushera produced in the laboratory was initially dominated by Enterobacteriaceae and later by Lactococcus spp. Enterobacteriaceae and Bacillus spp. were also detected in Ekitiribita. Development of starters for Obushera may require combinations of LAB and S. cerevisiae for Obutoko, Enturire and Obuteire and LAB for

  12. Impact of a continuing professional development intervention on midwifery academics' awareness of cultural safety.

    Science.gov (United States)

    Fleming, Tania; Creedy, Debra K; West, Roianne

    2017-06-01

    Cultural safety in higher education learning and teaching environments is paramount to positive educational outcomes for Aboriginal and/or Torres Strait Islander (hereafter called First Peoples) students. There is a lack of research evaluating the impact of continuing professional development on midwifery academics' awareness of cultural safety. To implement and evaluate a continuing professional development intervention to improve midwifery academics' awareness of cultural safety in supporting First Peoples midwifery students success. A pre-post intervention mixed methods design was used. Academics (n=13) teaching into a Bachelor of Midwifery program agreed to participate. The intervention consisted of two workshops and five yarning circles across a semester. Data included the Awareness of Cultural Safety Scale, self-assessment on cultural safety and perceptions of racism, evaluation of the intervention, participants' journal entries, and researcher's reflections. Responses on the Awareness of Cultural Safety Scale revealed significant improvement in participants' awareness of cultural safety. There was an upward trend in self-assessment ratings. Participants reported high levels of satisfaction with the intervention or workshops and yarning circles. Participants' journal entries revealed themes willingness to participate and learn, confidence as well as anger and distress. Increased awareness of cultural safety can be transformative for midwifery academics. Workshops and yarning circles can support academics in moving beyond a 'sense of paralysis' and engage in challenging conversations to transform their learning and teaching and in turn foster a culturally safe learning and teaching environment for First Peoples midwifery students towards success. Copyright © 2017 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

  13. Enriched cultures of lactic acid bacteria from selected Zimbabwean fermented food and medicinal products with potential as therapy or prophylaxis against yeast infections

    Directory of Open Access Journals (Sweden)

    Alec Chabwinja

    2017-10-01

    Full Text Available Objective: To investigate the antifungal activity of crude cultures of putative strains of lactic acid bacteria (LAB from a selection of Zimbabwean traditional and commercial food/ medicinal products against yeasts (strains of environmental isolates of Candida albicans and Rhodotorula spp.. Methods: Cultures of putative LAB from our selection of fermented products were enriched in de Man, Rogosa and Sharpe and isolated on de Man, Rogosa and Sharpe agar. Results: The crude microbial cultures from the products that showed high antifungal activities (zone of inhibition, mm were as follows: supernatant-free microbial pellet (SFMP from an extract of Melia azedarach leaves [(27.0 ± 2.5 mm] > cell-free culture supernatants (CFCS from Maaz Dairy sour milk and Mnandi sour milk [approximately (26.0 ± 1.8/2.5 mm] > CFCS and SFMP from Amansi hodzeko [(25.0 ± 1.5 mm] > CFCS from Parinari curatellifolia fruit [(24.0 ± 1.5 mm], SFMP from Parinari curatellifolia fruit [(24.0 ± 1.4 mm] and SFMP from mahewu [(20.0 ± 1.5 mm]. These cultures also showed high tolerance to acidic conditions (pH 4.0 and pH 5.0. However, culture from WAYA LGG (shown elsewhere to harbour antimicrobial activities showed no antifungal activity. The LAB could have inhibited yeasts by either competitive exclusion or the release of antimicrobial metabolites. Conclusions: Our cultures of LAB from a selection of Zimbabwean fermented products, especially Ziziphus mauritiana and fermented milk products have great potential for use as antifungal probiotics against yeast infections. Studies are ongoing to determine the exact mechanisms that are employed by the putative LAB to inhibit Candida albicans.

  14. Affective, Normative, and Continuance Commitment Levels across Cultures: A Meta-Analysis

    Science.gov (United States)

    Meyer, John P.; Stanley, David J.; Jackson, Timothy A.; McInnis, Kate J.; Maltin, Elyse R.; Sheppard, Leah

    2012-01-01

    With increasing globalization of business and diversity within the workplace, there has been growing interest in cultural differences in employee commitment. We used meta-analysis to compute mean levels of affective (AC; K=966, N=433,129), continuance (CC; K=428, N=199,831), and normative (NC; K=336, N=133,277) organizational commitment for as…

  15. Continuing Bonds in Bereaved Pakistani Muslims: Effects of Culture and Religion

    Science.gov (United States)

    Suhail, Kausar; Jamil, Naila; Oyebode, Jan; Ajmal, Mohammad Asir

    2011-01-01

    This study explores the bereavement process and continuing bond in Pakistani Muslims with the focus on how culture and religion influence these processes. Ten participants were interviewed and their transcribed interviews were analyzed using a grounded theory approach. Three main domains were identified from the narratives expressed by the…

  16. Regulation of ribulose-bisphosphate carboxylase activity and synthesis in Rhodopseudomonas blastica grown in continuous culture

    NARCIS (Netherlands)

    Sani, A.; Dijkhuizen, Lubbert

    1992-01-01

    The growth of Rhodopseudomonas blastica in continuous culture under different limitations show that the organism is metabolically versatile. It responds to changes in the environmental growth conditions which results in large variations in the amount of Ribulose-bisphosphate carboxylase/oxygenase

  17. Traditional ranching heritage and cultural continuity in the southwestern United States

    Science.gov (United States)

    Carol Raish; Alice M. McSweeney

    2008-01-01

    This study, conducted among ranchers on the Santa Fe and Carson National Forests in the Southwestern United States, examines the role of ranching in maintaining traditional heritage and cultural continuity. The mainly Hispanic ranching families of northern New Mexico first came into the region in 1598 with Spanish colonization. Many of the villages received community...

  18. PHOSPHATE-LIMITED GROWTH OF CHROMATIUM-VINOSUM IN CONTINUOUS CULTURE

    NARCIS (Netherlands)

    MAS, J; VANGEMERDEN, H

    Chromatium vinosum DSM 185 was grown in continuous culture at a constant dilution rate of 0.071 h-1 with sulfide as the only electron donor. The organism was subjected to conditions ranging from phosphate limitation (S(R-phosphate) = 2.7-mu-M and S(R-sulfide) = 1.8 mM) to sulfide limitation

  19. Physiology of Continuous Bone Marrow Culture Derived Permanent Granulocyte-Macrophage Progenitor Cells

    Science.gov (United States)

    1983-08-01

    continuous marrow cultures. As shown in the accompAnying figures, there was no effect of Lithium Chloride (Figure 2), Sodium Selenite (Figure 3...tosis, respiratory burst, superoxide generation, degranulation and bactericidal capacity. When injected at 107 cells per day over 5 days these cells

  20. Selection of Lactobacillus plantarum strains for their use as starter cultures in Algerian olive fermentations

    Directory of Open Access Journals (Sweden)

    Mokhbi, Abdelouahab

    2009-03-01

    Full Text Available The aim of this research was to evaluate some technological traits of L. plantarum strains previously isolated from fermented olives. For this purpose, 11 strains were tested for their in vitro antibiotic susceptibility, resistance to low pH values, acidifying activity, proteolytic activity, haemolytic activity, lactic acid and exopolysaccharide production and resistance to freeze-drying .Collectively, the strains were susceptible to most of the antibiotics tested and showed survival at pH 2. Most strains showed high (1.035 ± 0.29 to 0.912 ± 0.21 mmol/l ± sd of lactic acid or medium (0.556 ± 0.29 to 0.692 ± 0.18 mmol/l ±sd acidification activity with good proteolytic activity (1.49 ± 0.25 to 5.25 ± 0.11 mg L-1 tyrosine. None of the strains produced exopolysaccharides or haemolysis in sheep's blood.El objetivo de esta investigación fue evaluar algunos aspectos tecnológicos de cepas de L. plantarum previamente aisladas de aceitunas fermentadas. Para este propósito, 11 cepas fueron usadas para estudiar su susceptibilidad a antibióticos in vitro, resistencia a valores de pH bajos, actividad acidificante, proteolítica, y hemolítica, producción de ácido láctico y exopolisacáridos, y resistencia a la liofilización. En general, las cepas fueron susceptibles a la mayoría de los antibióticos ensayados y mostraron supervivencia a pH 2. La mayoría de las cepas mostraron una actividad de acidificación alta (1.035 ± 0.29 a 0.912 ± 0.21 mmol/l de ácido láctico o media (0.556 ± 0.29 a 0.692 ± 0.18 mmol/l con una buena actividad proteolítica (1.49 ± 0.25 a 5.25 ± 0.11 mg L-1 tirosina. Ninguna de las cepas produjo exopolisacáridos o hemolisis en sangre de oveja.

  1. Influence of starter culture and a protease on the generation of ACE-inhibitory and antioxidant bioactive nitrogen compounds in Iberian dry-fermented sausage “salchichón”

    National Research Council Canada - National Science Library

    Fernández, Margarita; Benito, María J; Martín, Alberto; Casquete, Rocío; Córdoba, Juan J; Córdoba, María G

    2016-01-01

    ...)-inhibitory and antioxidant compounds by the dry-fermented sausage “salchichón” was investigated. Sausages were prepared with purified EPg222 and Pediococcus acidilactici MS200 and Staphylococcus vitulus RS34 as the starter culture...

  2. Ammonia tolerant enriched methanogenic cultures as bioaugmentation inocula to alleviate ammonia inhibition in continuous anaerobic reactors

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Wang, Han; Angelidaki, Irini

    methanogens are more robust to ammonia toxicity effect. It has been shown that bioaugmentation of a pure strain of a hydrogenotrophic methanogen (i.e. Methanoculleus bourgensis) in an ammonia inhibited continuous anaerobic reactor can improve methane production more than 30%. Nevertheless, cultivation...... of a pure culture, to be used as bioaugmentation inoculum, poses technical difficulties due to the required sterile conditions and the special growing media. On the contrary acclimatized enrichment methanogenic cultures have lower requirements to sterility. In the present study, we used an enriched ammonia...... tolerant methanogenic culture as potential bioaugmentation inoculum in a continuous stirred tank reactor (CSTR) operating under “inhibited steady-state”, triggered by high ammonia levels (5 g NH4+-N L-1). The results of the current study established for the first time that bioaugmentation of an enriched...

  3. Comparison of Different Strategies for Selection/Adaptation of Mixed Microbial Cultures Able to Ferment Crude Glycerol Derived from Second-Generation Biodiesel

    DEFF Research Database (Denmark)

    Varrone, Cristiano; Heggeset, T. M. B.; Le, S. B.

    2015-01-01

    Objective of this study was the selection and adaptation of mixed microbial cultures (MMCs), able to ferment crude glycerol generated from animal fat-based biodiesel and produce building-blocks and green chemicals. Various adaptation strategies have been investigated for the enrichment of suitabl......,3-propanediol and butyrate production. Changes in microbial composition were monitored by means of Next Generation Sequencing, revealing a dominance of glycerol consuming species, such as Clostridium, Klebsiella, and Escherichia....

  4. Continuing Education Effects on Cultural Competence Knowledge and Skills Building among Health Professionals

    Directory of Open Access Journals (Sweden)

    Marla B. Hall

    2013-08-01

    Full Text Available Racial and ethnic minority health data from a national perspective indicates there is much to learn in the public health workforce about the ongoing health disparities crisis. This suggests a level of urgency to assist our public health professionals in obtaining specific skills sets that will assist them in working better with vulnerable populations. The purpose of this research is to assess cultural competence knowledge and programmatic skill sets, utilizing an explorational case study, of individuals employed within an urban public health department. In order to effectively evaluate these constructs, a quantitative research approach was employed to examine participants’ knowledge and competencies of the subject matter. This data was further analyzed to determine if continuing education participation and training was correlated to the levels of culturally competent practice engagement and self-reported confidence. In addition, researchers obtained data on the availability of employer sponsored training opportunities. The data suggested when health professionals engage in cultural competence education, their level of awareness of unique characteristics between ethnic and racial minorities increased. Those who exhibited the healthiest behaviors, as it relates to effectively working with diverse populations, had a heightened sense of knowledge related to culture and healthcare services. Continuing education in cultural competence is an essential strategy for improving public health employees’ effectiveness in working with diverse clients and reducing racial and ethnic health disparities. As the finding illustrated, training programs must incorporate educational components which foster skill building to enable subsequent culturally appropriate clinical interactions.

  5. Definition and dynamic control of a continuous chromatography process independent of cell culture titer and impurities.

    Science.gov (United States)

    Chmielowski, Rebecca A; Mathiasson, Linda; Blom, Hans; Go, Daniel; Ehring, Hanno; Khan, Heera; Li, Hong; Cutler, Collette; Lacki, Karol; Tugcu, Nihal; Roush, David

    2017-12-01

    Advances in cell culture technology have enabled the production of antibody titers upwards of 30g/L. These highly productive cell culture systems can potentially lead to productivity bottlenecks in downstream purification due to lower column loadings, especially in the primary capture chromatography step. Alternative chromatography solutions to help remedy this bottleneck include the utilization of continuous processing systems such as periodic counter-current chromatography (PCC). Recent studies have provided methods to optimize and improve the design of PCC for cell culture titers up to about 3g/L. This paper defines a continuous loading strategy for PCC that is independent of cell culture background and encompasses cell culture titers up to about 31g/L. Initial experimentation showed a challenge with determining a difference in change in UV280nm signal (ie. ΔUV) between cell culture feed and monoclonal antibody (mAb) concentration. Further investigation revealed UV280nm absorbance of the cell culture feedstock without antibody was outside of the linear range of detection for a given cell pathlength. Additional experimentation showed the difference in ΔUV for various cell culture feeds can be either theoretically predicted by Beer's Law given a known absorbance of the media background and impurities or experimentally determined using various UV280nm cell pathlengths. Based on these results, a 0.35mm pathlength at UV280nm was chosen for dynamic control to overcome the background signal. The pore diffusion model showed good agreement with the experimental frontal analysis data, which resulted in definition of a ΔUV setpoint range between 20 and 70% for 3C-PCC experiments. Product quality of the elution pools was acceptable between various cell culture feeds and titers up to about 41g/L. Results indicated the following ΔUV setpoints to achieve robust dynamic control and maintain 3C-PCC yield: ∼20-45% for titers greater than 10g/L depending on UV absorbance of

  6. L-lactic acid production from starch by simultaneous saccharification and fermentation in a genetically engineered Aspergillus oryzae pure culture.

    Science.gov (United States)

    Wakai, Satoshi; Yoshie, Toshihide; Asai-Nakashima, Nanami; Yamada, Ryosuke; Ogino, Chiaki; Tsutsumi, Hiroko; Hata, Yoji; Kondo, Akihiko

    2014-12-01

    Lactic acid is a commodity chemical that can be produced biologically. Lactic acid-producing Aspergillus oryzae strains were constructed by genetic engineering. The A. oryzae LDH strain with the bovine L-lactate dehydrogenase gene produced 38 g/L of lactate from 100g/L of glucose. Disruption of the wild-type lactate dehydrogenase gene in A. oryzae LDH improved lactate production. The resulting strain A. oryzae LDHΔ871 produced 49 g/L of lactate from 100g/L of glucose. Because A. oryzae strains innately secrete amylases, A. oryzae LDHΔ871 produced approximately 30 g/L of lactate from various starches, dextrin, or maltose (all at 100 g/L). To our knowledge, this is the first report describing the simultaneous saccharification and fermentation of lactate from starch using a pure culture of transgenic A. oryzae. Our results indicate that A. oryzae could be a promising host for the bioproduction of useful compounds such as lactic acid. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Co-culturing of Pichia guilliermondii enhanced volatile flavor compound formation by Zygosaccharomyces rouxii in the model system of Thai soy sauce fermentation.

    Science.gov (United States)

    Wah, Thin Thin; Walaisri, Supawan; Assavanig, Apinya; Niamsiri, Nuttawee; Lertsiri, Sittiwat

    2013-01-01

    The roles of salt-tolerant yeasts such as Zygosaccharomyces rouxii, Candida versatilis, and Candida etchellsii in the production of volatile flavor compounds (VFCs) in soy sauce fermentation have been well documented. However, the knowledge of VFC production by other salt-tolerant yeasts is still limited. In this work, the roles of Z. rouxii and Pichia guilliermondii strains in VFC production were investigated in moromi medium as a model system for soy sauce fermentation. Inoculation of a single culture of either Z. rouxii or P. guilliermondii as well as co-cultures of these two yeasts into moromi medium showed increased numbers of viable yeast at around 0.7 to 1.9 log CFU/mL after 7days of cultivation at 30°C. During cultivation, both single and co-cultures displayed survival over a 7-day time period, compared with the controls (no culture added). Overall, yeast inoculation enhanced the production of VFCs in the moromi media with higher amounts of ethanol, alcohols, furanones, esters, aldehyde, acid, pyrone and phenols, known as important characteristic flavor compounds in soy sauce. Moreover, the co-culture produced more alcohols, furanones, esters, maltol and benzoic acid than the single culture of Z. rouxii. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Metabolic activity and enzyme induction in rat fecal microflora maintained in continuous culture.

    Science.gov (United States)

    Mallett, A K; Bearne, C A; Rowland, I R

    1983-01-01

    The enzyme activity of the rat hindgut microflora maintained in an anaerobic two-stage continuous culture was compared with that of rat cecal contents. A qualitative comparison (API ZYM) showed a high degree of similarity between the two populations. Quantitative determinations showed that azoreductase, beta-glucosidase, nitrate reductase, and nitroreductase activities were comparable, and that beta-glucuronidase activity was very low in the culture. beta-Glucuronidase, beta-glucosidase, and nitrate reductase activities were induced within the culture by their respective substrates. Bile acids influenced microbial activity in vitro, with cholic acid inducing beta-glucosidase, azoreductase, and beta-glucuronidase activities and decreasing nitrate reductase activity. Chenodeoxycholic acid increased beta-glucosidase and beta-glucuronidase activities and decreased azoreductase, nitrate reductase, and nitroreductase activities in vitro. These studies demonstrate that the rat hindgut microflora may be successfully cultured in vitro and suggest control mechanisms that regulate the metabolic activity of these organisms in vivo. PMID:6416166

  9. Parameter oscillations in a very high gravity medium continuous ethanol fermentation and their attenuation on a multistage packed column bioreactor system.

    Science.gov (United States)

    Bai, F W; Chen, L J; Anderson, W A; Moo-Young, M

    2004-12-05

    The quasi-steady-states, marked by small fluctuations of residual glucose, ethanol, and biomass concentrations, and sustainable oscillations marked by big fluctuations of these monitored fermentation parameters were observed during the continuous ethanol fermentation of Saccharomyces cerevisiae when very high gravity media were fed and correspondingly high ethanol concentrations reached. A high ethanol concentration was shown to be one of the main factors that incited these oscillations, although the residual glucose level affected the patterns of these oscillations to some extent. The lag response of S. cerevisiae to high ethanol stress that causes the shifts of morphology, viability loss, and death of yeast cells is assumed to be one of the probable mechanisms behind these oscillations. It was predicted that the longer the delay of this response was, the longer the oscillation periods would be, which was validated by the experimental data and the comparison with the oscillatory behaviors reported for the ethanologen bacterium, Zymomonas mobilis. Furthermore, three tubular bioreactors in series were arranged to follow a stirred tank bioreactor to attenuate these oscillations. However, exaggerated oscillations were observed for the residual glucose, ethanol, and biomass concentrations measured in the broth from these tubular bioreactors. After the tubular reactors were packed with Intalox ceramic saddle packing, these oscillations were effectively attenuated and quasi-steady-states were observed during which there were very small fluctuations of residual glucose, ethanol, and biomass within the entire experimental run.

  10. Evaluation of continuous ethanol fermentation of dilute-acid corn stover hydrolysate using thermophilic anaerobic bacterium Thermoanaerobacter BG1L1

    DEFF Research Database (Denmark)

    Georgieva, Tania I.; Ahring, Birgitte Kiær

    2007-01-01

    Dilute sulfuric acid pretreated corn stover is potential feedstock of industrial interest for second generation fuel ethanol production. However, the toxicity of corn stover hydrolysate (PCS) has been a challenge for fermentation by recombinant xylose fermenting organisms. In this work...

  11. Enhancing acetone biosynthesis and acetone-butanol-ethanol fermentation performance by co-culturing Clostridium acetobutylicum/Saccharomyces cerevisiae integrated with exogenous acetate addition.

    Science.gov (United States)

    Luo, Hongzhen; Ge, Laibing; Zhang, Jingshu; Ding, Jian; Chen, Rui; Shi, Zhongping

    2016-01-01

    Acetone is the major by-product in ABE fermentations, most researches focused on increasing butanol/acetone ratio by decreasing acetone biosynthesis. However, economics of ABE fermentation industry strongly relies on evaluating acetone as a valuable platform chemical. Therefore, a novel ABE fermentation strategy focusing on bio-acetone production by co-culturing Clostridium acetobutylicum/Saccharomyces cerevisiae with exogenous acetate addition was proposed. Experimental and theoretical analysis revealed the strategy could, enhance C. acetobutylicum survival oriented amino acids assimilation in the cells; control NADH regeneration rate at moderately lower level to enhance acetone synthesis but without sacrificing butanol production; enhance the utilization ability of C. acetobutylicum on glucose and direct most of extra consumed glucose into acetone/butanol synthesis routes. By implementing the strategy using synthetic or acetate fermentative supernatant, acetone concentrations increased to 8.27-8.55g/L from 5.86g/L of the control, while butanol concentrations also elevated to the higher levels of 13.91-14.23g/L from 11.63g/L simultaneously. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Rumen fermentation patterns in buffalo bulls fed total mixed ration supplemented with exogenous fibrolytic enzyme and/or live yeast culture

    OpenAIRE

    Ravikanth Reddy Poonooru; Srinivasa Kumar Dhulipalla; Raghava Rao Eleneni; Ananda Rao Kancharana

    2015-01-01

    The objective of this study was to evaluate the effect of exogenous fibrolytic enzyme (EFE) and/or live yeast culture supplementation in total mixed ration (TMR) on rumen fermentation patterns in buffalo. For this, four adult buffalo bulls weighing 377.05+/-43.36 kg were randomly allotted to four dietary treatments viz., TMR containing R:C ratio of 70:30 (T1), T1 supplemented with EFE at 15 g/animal/day (T2), T1 supplemented with live yeast culture at 10 g/animal/day (T3), and T1 supplemented...

  13. A continuous culture of pluripotent fetal hepatocytes derived from the 8-day epiblast of the pig.

    Science.gov (United States)

    Talbot, N C; Rexroad, C E; Powell, A M; Pursel, V G; Caperna, T J; Ogg, S L; Nel, N D

    1994-12-01

    Continuous cultures of pluripotent parenchymal hepatocytes were derived from the epiblasts of 8-day-old pig blastocysts. The cells were polygonal and had phase-contrast dark, granular cytoplasm with prominent nuclei and nucleoli. These feeder-dependent cell cultures differentiated into large, multicellular, secretory, duct-like structures or formed small canaliculi between individual cells. Alternatively, the cells accumulated droplets that stained intensely with Oil Red O, a lipid-specific stain. Alpha-fetoprotein (AFP), albumin, and beta-fibrinogen mRNAs were expressed as the cells differentiated in culture. Serum-free medium that was conditioned by the cells contained transferrin, AFP, and albumin. The growth and viability of the cells were inhibited by transforming growth factor beta 1 (TGF beta 1) at concentrations > or = 1 ng/ml. The cell cultures grew slowly with doubling times of 2 to 3 d. One of the cultures, pig inner cell mass-19 (PICM-19), was passaged continuously for over 2 yr [> 100 population doublings (PD)] and appears to be an infinitely self-renewing cell population. The stem cell characteristics of the epiblast-derived fetal hepatocytes indicate that the cells may be unique for investigations of liver differentiation and organogenesis.

  14. Characterizing steady states of genome-scale metabolic networks in continuous cell cultures.

    Directory of Open Access Journals (Sweden)

    Jorge Fernandez-de-Cossio-Diaz

    2017-11-01

    Full Text Available In the continuous mode of cell culture, a constant flow carrying fresh media replaces culture fluid, cells, nutrients and secreted metabolites. Here we present a model for continuous cell culture coupling intra-cellular metabolism to extracellular variables describing the state of the bioreactor, taking into account the growth capacity of the cell and the impact of toxic byproduct accumulation. We provide a method to determine the steady states of this system that is tractable for metabolic networks of arbitrary complexity. We demonstrate our approach in a toy model first, and then in a genome-scale metabolic network of the Chinese hamster ovary cell line, obtaining results that are in qualitative agreement with experimental observations. We derive a number of consequences from the model that are independent of parameter values. The ratio between cell density and dilution rate is an ideal control parameter to fix a steady state with desired metabolic properties. This conclusion is robust even in the presence of multi-stability, which is explained in our model by a negative feedback loop due to toxic byproduct accumulation. A complex landscape of steady states emerges from our simulations, including multiple metabolic switches, which also explain why cell-line and media benchmarks carried out in batch culture cannot be extrapolated to perfusion. On the other hand, we predict invariance laws between continuous cell cultures with different parameters. A practical consequence is that the chemostat is an ideal experimental model for large-scale high-density perfusion cultures, where the complex landscape of metabolic transitions is faithfully reproduced.

  15. Microchemostat - microbial continuous culture in a polymer-based, instrumented microbioreactor

    DEFF Research Database (Denmark)

    Zhang, Z.; Bocazzi, P.; Choi, H. G.

    2006-01-01

    In a chemostat, microbial cells reach a steady state condition at which cell biomass production, substrates and the product concentrations remain constant. These features make continuous culture a unique and powerful tool for biological and physiological research. We present a polymer-based micro......In a chemostat, microbial cells reach a steady state condition at which cell biomass production, substrates and the product concentrations remain constant. These features make continuous culture a unique and powerful tool for biological and physiological research. We present a polymer......-based microbioreactor system integrated with optical density (OD), pH, and dissolved oxygen (DO) real-time measurements for continuous cultivation of microbial cells. Escherichia coli (E. coli) cells are continuously cultured in a 150 mL, membrane-aerated, well-mixed microbioreactor fed by a pressure-driven flow......(dimethylsiloxane) ( PDMS) of the microbioreactor are modified to generate bio-inert surfaces resistant to non-specific protein adsorption and cell adhesion. The modified surfaces of microbioreactor effectively reduce wall growth of E. coli for a prolonged period of cultivation. Steady state conditions at different...

  16. Computer graphics and cultural heritage, part 2: continuing inspiration for future tools.

    Science.gov (United States)

    Arnold, David

    2014-01-01

    The availability of large quantities of cultural-heritage data will enable new, previously inconceivable, types of analysis and new applications. Currently, most emerging analysis methods are experimental research. It's likely to take many years before the research matures and provides cultural-heritage professionals with novel research methods that they use routinely. Indeed, we can expect further disruptive technologies to emerge in the foreseeable future and a "steady state" of continuing rapid change. Part 1 can be found at 10.1109/MCG.2014.47.

  17. Suitability of the probiotic lactic acid bacteria strains as the starter cultures in unripe cornelian cherry (Cornus mas L.) fermentation.

    Science.gov (United States)

    Czyżowska, Agata; Kucharska, Alicja Z; Nowak, Agnieszka; Sokół-Łętowska, Anna; Motyl, Ilona; Piórecki, Narcyz

    2017-08-01

    This study examines the influence of lactic acid fermentation on iridoid and polyphenolic compounds in unripe Cornus mas L. fruits. Fermentation was carried out at room temperature over 6 weeks. Eight versions of the fermentation process were conducted: with inoculation by microflora isolated from black olives, Lb. brevis 18 M, Lb. casei 0919, Lb. paracasei 920, Lb. rhamnosus 0900, Lb. rhamnosus 0908, and spontaneous fermentation with and without summer savory (Satureja hortensis). The polyphenolic compounds, iridoids and antioxidant activities were examined in the products obtained. After fermentation, the polyphenols detected were: gallic acid and one of its derivatives, protocatechuic and ellagic acids, neochlorogenic and chlorogenic acids, and a chlorogenic acid derivative. Loganic acid and cornuside were found to be present in both the fermented fruits and the brines. The tested microorganisms produced varying amounts of lactic acid and had varying degrees of impact on the content of biologically active compounds. Lb. rhamnosus 908 proved to be the most effective strain. Unripe cornelian cherries fermented with probiotic strains could be used as an innovative pro-health product.

  18. ARCHITECTURAL CONSERVATION AS A TOOL FOR CULTURAL CONTINUITY: A Focus on the Built Environment of Islam

    Directory of Open Access Journals (Sweden)

    Hasan-Uddin Khan

    2015-03-01

    Full Text Available Architectural historic preservation has been used as a means to express or represent national, Islamic and even ethnic identity, and often this is linked to tourism or used to serve political ends, particularly in nation building. This article investigates agency and utility in the conservation and restoration of religious built environments in different societies in the Islamic world and its meaning to these societies today. Conservation should be interpreted more broadly than the physical continuity of historic structures; it should also enable the continuity of non-material aspects of culture.

  19. Use of the gfp gene in monitoring bacteriocin-producing Lactobacillus plantarum N014, a potential starter culture in nham fermentation.

    Science.gov (United States)

    Phumkhachorn, Parichat; Rattanachaikunsopon, Pongsak; Khunsook, Sumpars

    2007-02-01

    Lactobacillus plantarum N014 is a bacteriocin-producing lactic acid bacteria originally isolated from nham, a traditional Thai fermented sausage, and in the process of development to be used as a starter culture for nham fermentation. During the fermentation process, there is a need to identify the starter culture among several naturally occurring bacteria. In this study, a new plasmid carrying the gfp (green fluorescent protein) gene was constructed based on pGKV210, an Escherichia coli/ Lactococcus shuttle vector containing an erythromycin resistance marker. The gfp gene derived from pGFPuv was placed under the control of an L-lactate dehydrogenase promoter and then inserted at the EcoRI site of pGKV210, leading to pN014-GFP. The novel plasmid was used to transform L. plantarum N014, which is a bacteriocin-producing lactic acid bacteria isolated from nham. The resulting transformant, L. plantarum N014-GFP+, was brightly fluorescent and harbored the expected plasmid. A plasmid stability test revealed that pN014-GFP was stable after 100 generations of growth under nonselective pressure. L. plantarum N014-GFP+ and its parent strain were shown to be very similar in growth rate, bacteriocin production, and lactate production. L. plantarum N014-GFP+ was able to survive in a nham model. The survival clones were still fluorescent and harbored pN014-GFP.

  20. Determination of microbial diversity in Daqu, a fermentation starter culture of Maotai liquor, using nested PCR-denaturing gradient gel electrophoresis.

    Science.gov (United States)

    Xiu, Liu; Kunliang, Guo; Hongxun, Zhang

    2012-06-01

    This study endeavored to investigate the diversity of microbes present during the shaping, ripening and drying of Daqu, a fermentation starter culture and substrata complex of Maotai alcoholic spirit. A nested PCR-denaturing gradient gel electrophoresis technique was utilized with different combinations of primers. The results showed the presence of bacteria, yeasts and molds. The microflora, which originate from wheat, were readily detectable during every stage of the fermentation process. However, the microbial structure had clear differences in the shaping, ripening and drying processes. In the shaping stage, there was a high level of diversity of the LAB (lactic acid bacteria) and fungi in the shaped samples. In the ripening stage, however, a reduction of diversity of fungi with a high level of diversity of the Bacilli was observed in the ripened samples. In the drying stage, the diversity of Bacilli and fungi, especially acid-producing bacteria, reduced dramatically. Interestingly, uncultured Lactococcus sp., Microbacterium testaceum, Cochliobolus sp., and Thermoascus crustaceus were the first to be detected in the fermentation starters used in liquor production. This study revealed the microbial diversity and distributions during the shaping, ripening and drying of Daqu-making, facilitating evaluation of the hygienic conditions and aiding in the design of specific starter and/or adjunct cultures.

  1. PUSAKA SAUJANA BOROBUDUR: PERUBAHAN DAN KONTINUITASNYA (Borobudur Cultural Landscape: Change and Continuity

    Directory of Open Access Journals (Sweden)

    Dwita Hadi Rahmi

    2012-03-01

    Full Text Available ABSTRAK Penelitian ini dilakukan di kawasan Borobudur, Kabupaten Magelang, Jawa Tengah, untuk mengkaji potensi dan nilai keunggulan pusaka saujana Borobudur, serta mengetahui perubahan dan kontinuitasnya. Dengan interpretasi sejarah dan penjelasan secara naratif, wujud pusaka saujana Borobudur dapat diapresiasi dalam bentuk: a pola pengolahan lahan; b tata kehidupan; c arsitektur tradisional kawasan; dan d bentukan-bentukan alami. Potensi yang dimiliki pusaka saujana Borobudur meliputi potensi budaya, sejarah, bentukan-bentukan alami, dan panorama kawasan. Potensi-potensi yang dimiliki kawasan Borobudur, serta kontinuitas kondisi bentanglahan dan budayanya menjadikan kawasan Borobudur sebuah pusaka saujana yang unggul, dan nilai keunggulan ini meliputi: a kandungan sejarah lingkungan kawasan, b kawasan peninggalan benda-benda arkeologi, c saujana-saujana desa yang menunjukkan kehidupan agraris masyarakatnya, dan d panorama indah bentanglahan. Dalam lingkungan yang dinamis, pusaka saujana Borobudur terus mengalami perubahan yang dapat mengancam kontinuitasnya. Perubahan terjadi terutama pada tata guna lahan, kualitas visual, dan sebagian budaya masyarakat, sedangkan kontinuitas masih dapat ditemui pada kegiatan pertanian secara tradisional; sebagian tradisi atau adat istiadat yang berkaitan dengan pertanian, keagamaan, dan kepercayaan; arsitektur tradisional kawasan perdesaan; dan panorama indah bentanglahan. Sampai saat ini, perubahan-perubahan yang terjadi belum berdampak pada hilangnya atau menurunnya kontinuitas pusaka saujana Borobudur. Meskipun demikian, upaya-upaya pelestarian dan pengelolaannya diperlukan untuk menjaga kontinuitasnya.   ABSTRACT This research was conducted in Borobudur area, Magelang Regency, Central Java, to examine the potencies and  outstanding values of Borobudur cultural landscape heritage, and to understand its changes and continuity. By historic interpretation and narrative explanation, the forms of Borobudur

  2. Yeasts Diversity in Fermented Foods and Beverages

    Science.gov (United States)

    Tamang, Jyoti Prakash; Fleet, Graham H.

    People across the world have learnt to culture and use the essential microorganisms for production of fermented foods and alcoholic beverages. A fermented food is produced either spontaneously or by adding mixed/pure starter culture(s). Yeasts are among the essential functional microorganisms encountered in many fermented foods, and are commercially used in production of baker's yeast, breads, wine, beer, cheese, etc. In Asia, moulds are predominant followed by amylolytic and alcohol-producing yeasts in the fermentation processes, whereas in Africa, Europe, Australia and America, fermented products are prepared exclusively using bacteria or bacteria-yeasts mixed cultures. This chapter would focus on the varieties of fermented foods and alcoholic beverages produced by yeasts, their microbiology and role in food fermentation, widely used commercial starters (pilot production, molecular aspects), production technology of some common commercial fermented foods and alcoholic beverages, toxicity and food safety using yeasts cultures and socio-economy

  3. Production of microsclerotia by Brazilian strains of Metarhizium spp. using submerged liquid culture fermentation.

    Science.gov (United States)

    Mascarin, Gabriel Moura; Kobori, Nilce Naomi; de Jesus Vital, Rayan Carlos; Jackson, Mark Alan; Quintela, Eliane Dias

    2014-05-01

    We investigated the potential production and desiccation tolerance of microsclerotia (MS) by Brazilian strains of Metarhizium anisopliae (Ma), M. acridum (Mc) and M. robertsii (Mr). These fungi were grown in a liquid medium containing 16 g carbon l⁻¹ with a carbon:nitrogen ratio of 50:1. One hundred milliliters cultures were grown in 250 ml Erlenmeyer flasks in a rotary incubator shaker at 28 °C and 200 rpm for 5 days. Five-day-old MS were harvested, mixed with diatomaceous earth (DE) and air-dried for 2 days at 30 °C. The air-dried MS-DE granular preparations were milled by mortar + pestle and stored in centrifuged tubes at either 26 or -20 °C. Desiccation tolerance and conidia production were assessed for dried MS granules by measuring hyphal germination after incubation for 2 days on water agar plates at 26 °C and for conidia production following 7 days incubation. Yields of MS by all strains of Metarhizium were 6.1-7.3 × 10⁶ l⁻¹ after 3 days growth with maximum MS yields (0.7-1.1 × 10⁷ l⁻¹) after 5 days growth. No differences in biomass accumulation were observed after 3 days growth, whereas Ma-CG168 showed the highest biomass accumulation after 5 days growth. Dried MS-DE preparations of all fungal strains were equally tolerant to desiccation (≥93 % germination) and the highest conidia production was obtained by MS granules of Mc-CG423 (4 × 10⁹ conidia g⁻¹). All MS granules showed similar stability after storage at either 26 or -20 °C for 3.5 months.

  4. Suitability of the probiotic lactic acid bacteria strains as the starter cultures in unripe cornelian cherry (Cornus mas L.) fermentation

    National Research Council Canada - National Science Library

    Czyżowska, Agata; Kucharska, Alicja Z; Nowak, Agnieszka; Sokół-Łętowska, Anna; Motyl, Ilona; Piórecki, Narcyz

    2017-01-01

    ...: with inoculation by microflora isolated from black olives, Lb. brevis 18 M, Lb. casei 0919, Lb. paracasei 920, Lb. rhamnosus 0900, Lb. rhamnosus 0908, and spontaneous fermentation with and without summer savory...

  5. Extreme thermophilic biohydrogen production from wheat straw hydrolysate using mixed culture fermentation: effect of reactor configuration.

    Science.gov (United States)

    Kongjan, Prawit; Angelidaki, Irini

    2010-10-01

    Hydrogen production from hemicellulose-rich wheat straw hydrolysate was investigated in continuously-stirred tank reactor (CSTR), up-flow anaerobic sludge bed (UASB) reactor, and anaerobic filter (AF) reactor. The CSTR was operated at an hydraulic retention time (HRT) of 3 days, and the UASB and AF reactors were operated at 1 day HRT, using mixed extreme thermophiles at 70 °C. The highest hydrogen production yield of 212.0±6.6 mL-H₂/g-sugars, corresponding to a hydrogen production rate of 821.4±25.5 mL-H₂/dL was achieved with the UASB reactor. Lowering the HRT to 2.5 days caused cell mass washout in the CSTR, while the UASB and AF reactors gave fluctuating and reducing hydrogen production at a 0.5-day HRT. The original rate and yield were recovered when the HRT was increased back to 1 day. These results demonstrate that reactor configuration is an important factor for enhancing and stabilizing H₂ production. Copyright © 2010 Elsevier Ltd. All rights reserved.

  6. Microbiological characterization of traditional dough fermentation starter (Jiaozi) for steamed bread making by culture-dependent and culture-independent methods.

    Science.gov (United States)

    Li, Zhijian; Li, Haifeng; Bian, Ke

    2016-10-03

    In this study, the microbial composition of two types of Jiaozi (a dough fermentation starter in making steamed bread) was investigated using both culture-dependent and culture-independent (PCR-DGGE) methods. The numbers of the cultivable bacteria on MRS at 30°C and yeast on YPD at 28°C in the maize flour Jiaozi (MFJ) were 9.21±0.16 Log CFU/g and 9.18±0.05 Log CFU/g, respectively, which were higher than that in the rice flour Jiaozi (RFJ) (Pculture-dependent method showed that Acetobacter tropicalis and Enterococcus durans were the predominant bacteria strains in MFJ, and accounted for 45.7% and 25.7% of the bacteria, and Lactobacillus plantarum and Pediococcus pentosaceus represented 12.8% and 8.6%. In the RFJ sample, the most prominent isolate was P. pentosaceus (38.6%), followed by L. plantarum (24.3%), A. tropicalis (22.8%), and E. durans (5.7%). P. pentosaceus and L. plantarum were also detected in both starters by PCR-DGGE, while some bacteria species such as A. tropicalis and E. durans, recovered as pure cultures, were not detected by direct PCR-DGGE. On the other hand, Lactobacillus brevis, Weissella sp. and Lactobacillus alimentarius detected by PCR-DGGE were not recovered in any of the media and conditions used. In the MFJ sample, the isolated main yeast species were identified as Wickerhamomyces anomalus (67.2%), Saccharomyces cerevisiae (27.9%) and Torulaspora delbrueckii (4.9%). In addition to S. cerevisiae (42.9%), W. anomalus (27.0%) and T. delbrueckii (7.9%), Saccharomycopsis fibuligera was also identified as the predominant isolate in RFJ samples and accounted for 22.2%. PCR-DGGE also indicated the presence of W. anomalus and S. cerevisiae in both MFJ and RFJ starters and S. fibuligera was also detected in RFJ, but T. delbrueckii was not detected in both samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Selection of ethanol-tolerant yeast hybrids in pH-regulated continuous culture

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, J.; Benitez, T.

    1988-04-01

    Hybrids between naturally occurring wine yeast strains and laboratory strains were formed as a method of increasing genetic variability to improve the ethanol tolerance of yeast strains. The hybrids were subjected to competition experiments under continuous culture controlled by pH with increasing ethanol concentrations over a wide range to select the fastest-growing strain at any concentration of ethanol. The continuous culture system was obtained by controlling the dilution rate of a chemostat connected to a pH-meter. The nutrient pump of the chemostat was switched on and off in response to the pH of the culture, which was thereby kept near a critical value (pH/sub c/). Under these conditions, when the medium was supplemented with ethanol, the ethanol concentration of the culture increased with each pulse of dilution. A hybrid strain was selected by this procedure that was more tolerant than any of the highly ethanol-tolerant wine yeast strains at any concentration of ethanol and was able to grow at up to 16% (vol/vol) ethanol. This improvement in ethanol tolerance led to an increase in both the ethanol production rate and the total amount of ethanol produced.

  8. Characterisation and biochemical properties of predominant lactic acid bacteria from fermenting cassava for selection as starter cultures

    CSIR Research Space (South Africa)

    Kostinek, M

    2007-03-01

    Full Text Available of major food crops in developing countries after rice, wheat and maize (Mingli et al., 1992). Cassava grows in poor and acidic soils, which are often not suitable for other crops, and a Federal Research Centre for Nutrition and Food, Institute... (Moorthy and Mathew, 1998). Cassava fermentation for the production of Gari is associated with the fermentative activities of bacteria and yeasts (Moorthy and Mathew, 1998). The positive effects of these microorganisms are thought to include product...

  9. Aroma profile of Montepulciano d’Abruzzo wine fermented by single and co-culture starters of autochthonous Saccharomyces and non-Saccharomyces yeasts

    Directory of Open Access Journals (Sweden)

    Rosanna eTofalo

    2016-04-01

    Full Text Available Montepulciano d’Abruzzo is a native grape variety of Vitis vinifera L., grown in central Italy and used for production of high quality red wines. Limited studies have been carried out to improve its enological characteristics through the use of indigenous strains of Saccharomyces cerevisiae. The main objective of the present work was to test two indigenous strains of S. cerevisiae (SRS1, RT73, a strain of Starm. bacillaris (STS12, one of H. uvarum (STS45 and a co-culture of S. cerevisiae (SRS1 and Starm. bacillaris (STS12, in an experimental cellar to evaluate their role in the sensory characteristic of Montepulciano d’Abruzzo wine. A S. cerevisiae commercial strain was used. Fermentations were conducted under routine Montepulciano d’Abruzzo wine production, in which the main variables were the yeast strains used for fermentation. Basic winemaking parameters, some key chemical analysis and aroma compounds were considered. Saccharomyces cerevisiae strain dynamics during fermentation were determined by molecular methods. The musts inoculated with the co-culture were characterized by a faster fermentation start and a higher content of glycerol after three days of fermentation, as well as the musts added with strains Starm. bacillaris (STS12 and H. uvarum (STS45. At the end of fermentation the parameters studied were quite similar in all the wines. Total biogenic amines (BA content of all the wines was low. Ethanolamine was the predominant BA, with a concentration ranging from 21 to 24 mg/l. Wines were characterized by esters and alcohols. In particular, 2-phenylethanol, 3-methylbut-1-yl methanoate and ethyl ethanoate were the major aroma volatile compounds in all wines. Statistical analysis highlighted the different role played by aroma compounds in the differentiation of wines, even if it was impossible to select a single class as the most important for a specific yeast. The present study represents a further step towards the use of tailored

  10. Effect of Novel Starter Culture on Reduction of Biogenic Amines, Quality Improvement, and Sensory Properties of Doenjang, a Traditional Korean Soybean Fermented Sauce Variety.

    Science.gov (United States)

    Shukla, Shruti; Lee, Jong Suk; Park, Hae-Kyong; Yoo, Jung-Ah; Hong, Sung-Yong; Kim, Jong-Kyu; Kim, Myunghee

    2015-08-01

    To select appropriate microorganisms as starter cultures for the reliable and reproducible fermentation of soybean fermented products of Korean Doenjang, various ratios of fungi (Aspergillus oryzae J, Mucor racemosus 15, M. racemosus 42) combined with Bacillus subtilis TKSP 24 were selected as either single, double, or multiple Meju strains for commercial mass production of Doenjang, followed by analysis of sensory characteristics. In the sensory evaluation, Doenjang BAM15-1 and BAM42-1, which were fermented with multiple strains (1:1:1), showed the highest sensory scores as compared to control. Based on sensory characteristics, 6 Doenjang samples were subjected to quantitative determination of amino acids, free sugars, and organic acids (volatile and nonvolatile) contents, followed by determination of biogenic amines. Total sweet taste amino acid contents were highest in BAM15-1 and BAM42-1 samples (333.7 and 295.8 mg/100 g, respectively) and similar that of control (391.1 mg/100 g). Samples BAM15-1 and BAM42-1 showed the relatively high volatile and nonvolatile organic acid contents (154.24, 192.26, and 71.31, 82.42 mg/100 g, respectively). In addition, BAM15-1 and BAM42-1 showed negligible biogenic amine formation, ranging from 0.00 to 1.02 and 0.00 to 3.92 mg/100 g, respectively. These findings indicate that determination of food components along with sensory and quality attributes using multiple microbial Meju strains as a starter culture may provide substantial results on improved quality fermented Doenjang products. © 2015 Institute of Food Technologists®

  11. The Use of Plastic Lemonade Bottles as Fermenter Reaction Vessels.

    Science.gov (United States)

    Walker, David; Howard, Barry

    1988-01-01

    Describes the construction and uses of a low cost fermenter reaction vessel which is suitable for laboratory growth of microorganisms by continuous and batch cultures from plastic soft drink bottles. Lists materials, discusses modifications that can be made and gives examples of use. (CW)

  12. Bioprocess Intensification of Beer Fermentation Using Immobilised Cells

    Science.gov (United States)

    Verbelen, Pieter J.; Nedović, Viktor A.; Manojlović, Verica; Delvaux, Freddy R.; Laskošek-Čukalović, Ida; Bugarski, Branko; Willaert, Ronnie

    Beer production with immobilised yeast has been the subject of research for approximately 30 years but has so far found limited application in the brewing industry, due to engineering problems, unrealised cost advantages, microbial contaminations and an unbalanced beer flavor (Linko et al. 1998; Brányik et al. 2005; Willaert and Nedović 2006). The ultimate aim of this research is the production of beer of desired quality within 1-3 days. Traditional beer fermentation systems use freely suspended yeast cells to ferment wort in an unstirred batch reactor. The primary fermentation takes approximately 7 days with a subsequent secondary fermentation (maturation) of several weeks. A batch culture system employing immobilization could benefit from an increased rate of fermentation. However, it appears that in terms of increasing productivity, a continuous fermentation system with immobilization would be the best method (Verbelen et al. 2006). An important issue of the research area is whether beer can be produced by immobilised yeast in continuous culture with the same characteristic as the traditional method.

  13. Building a Culture of Continuous Quality Improvement in an Academic Radiology Department.

    Science.gov (United States)

    Katzman, Gregory L; Paushter, David M

    2016-04-01

    As we enter a new era of health care in the United States, radiologists must be adequately prepared to prove, and continually improve, our value to our customers. This goal can be achieved in large part by providing high-quality services. Although quality efforts on the national and international levels provide a framework for improving radiologic quality, some of the greatest opportunities for quality improvement can be found at the departmental level, through the implementation of total quality management programs. Establishing such a program requires not only strong leadership and employee engagement, but also a firm understanding of the multiple total quality management tools and continuous quality improvement strategies available. In this article, we discuss key tools and strategies required to build a culture of continuous quality improvement in an academic department, based on our experience. Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  14. Continuous cultures of Methanobacterium thermoautotrophicum: thermodynamic analysis, growth physiology and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Schill, N.A.

    1996-12-31

    Methanogens perform the last step of anaerobic degradation of organic matter the oxidation of H{sub 2} and concomitant reduction of CO{sub 2} to methane. Since anaerobic waste degradation is only successful if the H{sub 2} concentration is kept low, methanogens are the key-organism of such processes.The present study dealt with different aspects of the growth of the anaerobic archaebacterium M. thermoautotrophicum. This bacterium generates the energy necessary for cell synthesis through methanogenesis. Growth of M. thermoautotrophicum is characterized by some particularities which instigated the present work: the energy and carbon sources are both gaseous substrates; only low biomass yields can be achieved; growth is highly exothermic; uncoupling of catabolism from anabolism is possible. The energy substrate H{sub 2} is most often the growth limiting substrate because of its poor solubility in water. Therefore, a simple measurement device for monitoring of dissolved H{sub 2} concentration was developed based on a commercially available pO{sub 2}-probe. Chlorine ions (which are present in the electrolyte) caused deactivation of the electrode when used as a pH{sub 2}-probe, and the system had to be modified accordingly in order to obtain a measurement device that is suitable for long-term application in continuous cultures of M. thermoautotrophicum. A simple, unstructured mathematical model describing growth in continuous cultures limited by a gaseous substrate was developed. The model is based on a Michaelis-Menten type saturation kinetics and uses the appropriate gas-liquid mass transfer equations. The fact that the gaseous substrate supply is independent of the dilution rate is reflected in the growth performance in gaseous substrate limited continuous cultures: constant conversion rates of substrates and products, as well as a hyperbolic reduction of the biomass concentration with increasing dilution rate characterize such cultures. (author)

  15. Effect of time of cutting and maceration on nutrient flow, microbial protein synthesis, and digestibility in dual-flow continuous culture.

    Science.gov (United States)

    Kokko, C; Soder, K J; Brito, A F; Hovey, R C; Berthiaume, R

    2013-04-01

    Maceration and evening-cutting are 2 forage management techniques that have independently improved forage quality and nutrient utilization in ruminants, but have not been evaluated in combination. Using a dual-flow continuous culture fermenter system, this preliminary study was designed to evaluate the individual and combined effects of time of cutting and maceration on in vitro ruminal digestion, nutrient flows, and microbial protein synthesis. Forages were harvested as hay from a timothy (Phleum pratense L.)-birdsfoot trefoil (Lotus corniculatus L.) stand in the morning (AM) or evening (PM). Half of each morning- and evening-cut treatment was macerated (AM-M, PM-M). The chemical composition (DM, OM, CP, NDF, ADF), including nonstructural carbohydrates (NSC) and water-soluble carbohydrates (WSC), was determined for each of the 4 treatments (AM, AM-M, PM, PM-M). Forages were ground to 2 mm and allocated to separate fermenters at 60 g of DM/d in a 4 × 4 Latin square design. Fermenters were operated over four 10-d periods with the first 7 d for adaptation followed by 3 d of sampling. Evening-cutting enhanced the apparent digestibility of NDF (P = 0.02) and ADF (P = 0.006), with a tendency (P digestibility and microbial protein synthesis. Molar proportions of individual VFA were not affected (P > 0.10) by time of cutting, though evening-cutting increased (P = 0.02) total concentration of VFA. Maceration had no effect (P > 0.10) on true nutrient digestibility or microbial protein synthesis. An interaction of time of cutting and maceration (P digestibilities in evening-cut treatments, but had no effect in morning-cut treatments. Similarly, maceration reduced total N supply (P digestibility and total VFA concentration, and independent use of maceration shifted molar proportions of VFA toward glucogenic fermentation. The combined use of these management techniques afforded no improvement for in vitro digestibility or metabolism when applied to morning-cut hay, and

  16. Optical biosensor optimized for continuous in-line glucose monitoring in animal cell culture.

    Science.gov (United States)

    Tric, Mircea; Lederle, Mario; Neuner, Lisa; Dolgowjasow, Igor; Wiedemann, Philipp; Wölfl, Stefan; Werner, Tobias

    2017-09-01

    Biosensors for continuous glucose monitoring in bioreactors could provide a valuable tool for optimizing culture conditions in biotechnological applications. We have developed an optical biosensor for long-term continuous glucose monitoring and demonstrated a tight glucose level control during cell culture in disposable bioreactors. The in-line sensor is based on a commercially available oxygen sensor that is coated with cross-linked glucose oxidase (GOD). The dynamic range of the sensor was tuned by a hydrophilic perforated diffusion membrane with an optimized permeability for glucose and oxygen. The biosensor was thoroughly characterized by experimental data and numerical simulations, which enabled insights into the internal concentration profile of the deactivating by-product hydrogen peroxide. The simulations were carried out with a one-dimensional biosensor model and revealed that, in addition to the internal hydrogen peroxide concentration, the turnover rate of the enzyme GOD plays a crucial role for biosensor stability. In the light of this finding, the glucose sensor was optimized to reach a long functional stability (>52 days) under continuous glucose monitoring conditions with a dynamic range of 0-20 mM and a response time of t 90 ≤ 10 min. In addition, we demonstrated that the sensor was sterilizable with beta and UV irradiation and only subjected to minor cross sensitivity to oxygen, when an oxygen reference sensor was applied. Graphical abstract Measuring setup of a glucose biosensor in a shake flask for continuous glucose monitoring in mammalian cell culture.

  17. Importance of Typological Analysis in Architecture for Cultural Continuity: An Example from Kocaeli (Turkey)

    Science.gov (United States)

    Ayyıldız, Sonay; Ertürk, Filiz; Durak, Şahin; Dülger, Alper

    2017-10-01

    Cities are formed from historical layers. When different periods are examined, it is possible to reach out the information about the relation with the built environment created with the society’s owned culture and the location where the built environment is through these historical layers. Cultural and natural values owned by the city, shape the city identity. To have a city identity, it is necessary to provide the continuity of these values and to protect moral and material values which transfer messages of city’s past to its future. City identities in the World and in Turkey have been gradually disappearing because of the immigrations which are the results of globalization and industrialization. This situation creates the feeling of “Alienation” in the people who live in the city. Also in Kocaeli, which lost its’ agricultural city feature owned until 1960s and whose industrial city feature has come into prominence for 50 years, same problems can be observed. Traditional houses are formed depending on the society’s different cultural values. Some places in the traditional houses have disappeared completely or have become useless time-dependently. That’s why it is very important to reveal the local similarities. Thanks to the datum gathered by analysing with the Typology method, the historical traces will be the guiding light of continuing structuring and future. On this purpose, Kapanca Street has been chosen as study area. This street is one of the historical layers of Kocaeli city and which is one of the rare places still protecting the authenticity. There are 10 traditional registered houses belonging to the late Ottoman Period in the end of 19th century and the beginning of 20th century on this street. The values of Kapanca Street, which constitutes an important place in the historical identity of Kocaeli and has a historical background more than a century are thought to be in need of being recorded to provide the cultural continuity and to be

  18. Growth and enzyme synthesis during continuous culture of Trichosporon cutaneum on phenol

    Energy Technology Data Exchange (ETDEWEB)

    Spanning, A.; Neujahr, H.

    1987-03-01

    The soil yeast Trichosporon cutaneum was grown in continuous culture with phenol as the sole carbon source. The cultures were operated as carbon-limited chemostats or as steady-state continuous cultures without carbon limitation. Selected comparative runs were also conducted on glucose or acetate as carbon source. In addition to growth parameters, the activities of several intracellular enzymes were determined, comprising those directly involved in the degradation of phenol as well as auxiliary enzymes required for the generation of reducing power. All enzymes were assayed in detergent-permeabilized cells. Phenol was found to serve as an excellent carbon source, comparable to glucose or acetate. The utilization of phenol in T. cutaneum is very efficient as indicated by a low maintenance requirement (0.01 g phenol/g cells.h). The cell yields obtained were of the order of 0.8 g cells/g phenol. Although the phenol-limited chemostats were run with fully phenol-induced cells, a further increase in the activities of isocitrate DH(NADP+), maleate DH and the phenol-degrading enzyme occurred after transition to nonlimiting conditions. Enzyme activities increased in parallel with increasing phenol levels in the effluent, as well as with increasing toxicity. The significance of this phenomenon is discussed. This elevation in enzyme activities is not related to an increase in specific growth rate. 30 references.

  19. Fermentative production of poly (γ-glutamic acid) from renewable carbon source and downstream purification through a continuous membrane-integrated hybrid process.

    Science.gov (United States)

    Kumar, Ramesh; Pal, Parimal

    2015-02-01

    Experimental investigations were carried out on continuous and direct production of poly-(γ-glutamic acid) in a hybrid reactor system that integrated conventional fermentative production step with membrane-based downstream separation and purification. Novelty of the integrated system lies in high degree of purity, conversion, yield and productivity of poly-(γ-glutamic acid) through elimination of substrate-product inhibitions of traditional batch production system. This new system is compact, flexible, eco-friendly and largely fouling-free ensuring steady and continuous production of poly-(γ-glutamic acid) directly from a renewable carbon source at the rate of 0.91 g/L/h. Cross-flow microfiltration membrane modules ensured almost complete separation and recycle of cells without much fouling problem. Well-screened ultrafiltration membrane module helped to concentrate poly-(γ-glutamic acid) while ensuring recovery and recycle of 96% unconverted carbon source resulting in yield of 0.6g/g along with high product purity. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Macromolecular composition of a Cellulomonas sp. cultivated in continuous culture under glucose and zinc limitation.

    Science.gov (United States)

    Summers, R J; Srinivasan, V R

    1979-01-01

    The mutant strain of Cellulomonas sp. (ATCC 21399) was cultivated under glucose and zinc limitation at a variety of growth rates in continuous culture. The growth characteristics and macromolecular composition of the population varied with the limitation imposed and the growth rate. Glucose- and zinc-limited cultures maintained a constant relative protein content. The relative ribonucleic acid content increased, whereas the carbohydrate and deoxyribonucleic acid contents decreased with an increase in the population growth rate in glucose-limited cultures. Free unbound lipid remained constant. The maximum population growth rate in zinc-limited cultures was directly proportional to the zinc concentration and demonstrated a traditional steady-state function. The nucleic acid content increased with increased growth rate; however, the relative nucleic acid content was significantly depressed when compared to glucose limited cells. This manner of cultivation may prove to be a useful tool for the production of single cell protein with lowered nucleic acid content and the elucidation of micronutrient involvement in growth-related processes. PMID:114114

  1. Effect of sole or combined administration of nitrate and 3-nitro-1-propionic acid on fermentation and Salmonella survivability in alfalfa-fed rumen cultures in vitro.

    Science.gov (United States)

    Correa, Alejandro Castañeda; Trachsel, Julian; Allen, Heather K; Corral-Luna, Agustin; Gutierrez-Bañuelos, Hector; Ochoa-Garcia, Pedro Antonia; Ruiz-Barrera, Oscar; Hume, Michael E; Callaway, Todd R; Harvey, Roger B; Beier, Ross C; Anderson, Robin C; Nisbet, David J

    2017-04-01

    Ruminal methanogenesis is a digestive inefficiency resulting in the loss of dietary energy consumed by the host and contributing to environmental methane emission. Nitrate is being investigated as a feed supplement to reduce rumen methane emissions but safety and efficacy concerns persist. To assess potential synergies of co-administering sub-toxic amounts of nitrate and 3-nitro-1-propionate (NPA) on fermentation and Salmonella survivability with an alfalfa-based diet, ruminal microbes were cultured with additions of 8 or 16mM nitrate, 4 or 12mM NPA or their combinations. All treatments decreased methanogenesis compared to untreated controls but volatile fatty acid production and fermentation of hexose were also decreased. Nitrate was converted to nitrite, which accumulated to levels inhibitory to digestion. Salmonella populations were enriched in nitrate only-treated cultures but not in cultures co- or solely treated with NPA. These results reveal a need for dose optimization to safely reduce methane production with forage-based diets. Published by Elsevier Ltd.

  2. Studies on changes in microstructure and proteolysis in cow and soy milk curd during fermentation using lactic cultures for improving protein bioavailability.

    Science.gov (United States)

    Ghosh, Debasree; Chattoraj, Dipti K; Chattopadhyay, Parimal

    2013-10-01

    Cow milk curd was prepared using 2% v/v of Streptococcus thermophilus DG1 and a mixed culture (0.5:1.5 v/v) of S. thermophilus DG1 and Lactobacillus plantarum and incubating at 37 °C for 16 h. Soy milk curd was prepared using different ratios of lactic cultures as stated earlier and also a mixed culture containing S. thermophilus DG1, L. plantarum and Leuconostoc mesenteroides sub spp. mesenteroides in the ratio 1:1:1 v/v along with beet pulp (2% w/w) and incubating at 37 °C for 18 h. This improved functional and probiotic properties of curd. Structural changes in curd samples during fermentation were observed by Scanning Electron Microscope (SEM). Soy milk curd showed loosened structure. The degradation of proteins into peptides and amino acids were evaluated by SDS PAGE and amino acid analysis. Maximum production of amino acids i.e. cystine, histidine and asparagine were observed in both the cow and soymilk after fermentation.

  3. Effect of Aloe vera (Aloe barbadensis Miller) on survivability, extent of proteolysis and ACE inhibition of potential probiotic cultures in fermented milk.

    Science.gov (United States)

    Basannavar, Santosh; Pothuraju, Ramesh; Sharma, Raj Kumar

    2014-10-01

    In the present investigation, the effect of Aloe vera gel powder on angiotensin-converting enzyme (ACE) inhibitory activity, extent of proteolysis during fermentation and survival of Lactobacillus casei NCDC19 during storage of fermented milk was studied. Among the different cultures screened for ACE inhibitory activity, Lactobacillus casei NCDC 19 exhibited the highest ACE inhibition (approx. 40%) as well as extent of proteolysis (0.37, Abs₃₄₀). In the presence of Aloe vera (0.5% and 1% w/v) an increase in extent of proteolysis (0.460 ± 0.047 and 0.480 ± 0.027) and percent ACE inhibitory activity (44.32 ± 2.83 and 47.52 ± 1.83) was observed in comparison to control. Aloe vera powder addition also led to an increase in viable counts (>11 log cfu mL⁻¹) of L. casei NCDC 19 in fermented milk during storage for 7 days and the counts were maintained in sufficiently higher numbers. The study suggests Aloe vera to be a good functional ingredient which can be further explored for different health attributes. © 2014 Society of Chemical Industry.

  4. Continuous fermentation and in-situ reed separation of butyric acid for higher sugar consumption rate and productivity

    DEFF Research Database (Denmark)

    Baroi, George Nabin; Skiadas, Ioannis; Westermann, Peter

    and development, and process improvement for higher yield, productivity and selectivity. Compared with other microbial strains Clostridium tyrobutyricum has been well characterised, exhibits higher yield and selectivity and can utilize glucose and xylose simultaneously. However, a prerequisite for cost effective...... that disconnection of the REED system resulted to much lower (48 and 83% for glucose and xylose, respectively) sugars consumption rates and consequently lower butyric acid production rates. It was also noticeable that continuous operation, even without the REED system, resulted to higher glucose consumption rates...

  5. Culture-independent analyses reveal novel Anaerolineaceae as abundant primary fermenters in anaerobic digesters treating waste activated sludge

    DEFF Research Database (Denmark)

    McIlroy, Simon Jon; Kirkegaard, Rasmus Hansen; Dueholm, Morten Simonsen

    2017-01-01

    primary and surplus sludge from wastewater treatment plants, yet are known only by their 16S rRNA gene sequence. This study applied metagenomics to obtain a complete circular genome (2.57 Mbp) from a representative of the A6 taxon. Preliminary annotation of the genome indicates these organisms...... to be anaerobic chemoorganoheterotrophs with a fermentative metabolism. Given their observed abundance, they are likely important primary fermenters in digester systems. Application of fluorescence in situ hybridisation probes designed in this study revealed their morphology to be short filaments present within...

  6. Ammonia tolerant enriched methanogenic cultures as bioaugmentation inocula to alleviate ammonia inhibition in continuous anaerobic reactors

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Wang, Han; Angelidaki, Irini

    Ammonia is the most common inhibitor of anaerobic digestion (AD) process, resulting in suboptimal exploitation of the biogas potential of the feedstocks, causing significant economic losses to the biogas plants. Ammonia is mainly inhibiting the aceticlastic methanogens, while the hydrogenotrophic...... methanogens are more robust to ammonia toxicity effect. It has been shown that bioaugmentation of a pure strain of a hydrogenotrophic methanogen (i.e. Methanoculleus bourgensis) in an ammonia inhibited continuous anaerobic reactor can improve methane production more than 30%. Nevertheless, cultivation...... tolerant methanogenic culture as potential bioaugmentation inoculum in a continuous stirred tank reactor (CSTR) operating under “inhibited steady-state”, triggered by high ammonia levels (5 g NH4+-N L-1). The results of the current study established for the first time that bioaugmentation of an enriched...

  7. Use of real time gas production data for more accurate comparison of continuous single-stage and two-stage fermentation.

    Science.gov (United States)

    Massanet-Nicolau, Jaime; Dinsdale, Richard; Guwy, Alan; Shipley, Gary

    2013-02-01

    Changes in fermenter gas composition within a given 24h period can cause severe bias in calculations of biogas or energy yields based on just one or two measurements of gas composition per day, as is common in other studies of two-stage fermentation. To overcome this bias, real time recording of gas composition and production were used to undertake a detailed and controlled comparison of single-stage and two-stage fermentation using a real world substrate (wheat feed pellets). When a two-stage fermentation system was used, methane yields increased from 261 L kg(-1)VS using a 20 day HRT, single-stage fermentation, to 359 L kg(-1) VS using a two-stage fermentation with the same overall retention time--an increase of 37%. Additionally a hydrogen yield of 7 L kg(-1) VS was obtained when two-stage fermentation was used. The two-stage system could also be operated at a shorter, 12 day HRT and still produce higher methane yields (306 L kg(-1) VS). Both two-stage fermentation systems evaluated exhibited methane yields in excess of that predicted by a biological methane potential test (BMP) performed using the same feedstock (260 L kg(-1)VS). Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Dry fermentation of manure with straw in continuous plug flow reactor: Reactor development and process stability at different loading rates.

    Science.gov (United States)

    Patinvoh, Regina J; Kalantar Mehrjerdi, Adib; Sárvári Horváth, Ilona; Taherzadeh, Mohammad J

    2017-01-01

    In this work, a plug flow reactor was developed for continuous dry digestion processes and its efficiency was investigated using untreated manure bedded with straw at 22% total solids content. This newly developed reactor worked successfully for 230days at increasing organic loading rates of 2.8, 4.2 and 6gVS/L/d and retention times of 60, 40 and 28days, respectively. Organic loading rates up to 4.2gVS/L/d gave a better process stability, with methane yields up to 0.163LCH4/gVSadded/d which is 56% of the theoretical yield. Further increase of organic loading rate to 6gVS/L/d caused process instability with lower volatile solid removal efficiency and cellulose degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. The effects of co-culturing non-Saccharomyces yeasts with S. cerevisiae on the sugar cane spirit (cachaça) fermentation process.

    Science.gov (United States)

    Duarte, Whasley Ferreira; Amorim, Juliana Cunha; Schwan, Rosane Freitas

    2013-01-01

    Twenty non-Saccharomyces strains were previously tested in pure culture for their ability to grow in 12 % ethanol, their β-glucosidase activity, flocculation, glycerol, ethanol and acetic acid production, fermentation kinetics and their production of volatile compounds. Of these 20 strains, three strains, namely, Pichia anomala UFLA CAF70, P. anomala UFLA CAF119 and Pichia caribbica UFLA CAF733, were evaluated in co-culture with Saccharomyces cerevisiae UFLA CA11. Of the mixed inocula, the mixture of P. caribbica UFLA CAF733 and S. cerevisiae UFLA CA11 gave the highest ethanol concentration (75.37 g/L), the lowest levels of residual glucose (1.14 g/L) and fructose (19.92 g/L), and the highest volumetric productivity (Q (p)) of ethanol. Twenty-three minor volatile compounds were identified in the fermented sugar cane juice. The mixed culture of P. caribbica UFLA CAF733 and S. cerevisiae UFLA CA11 gave the highest concentration of volatile compounds with good sensory descriptors; these compounds included ethyl esters (290.13 μg/L), acetates (715.21 μg/L) and monoterpenic alcohols (195.56 μg/L). This mixed culture also gave the lowest concentration of volatile acids (1774.46 μg/L) and aldehydes (121.10 μg/L). In principal component analysis, the mixed inoculum of UFLA CAF733 and UFLA CA11 was positively characterized by ethyl hexanoate, 2-phenylethanol, linalool, nonanoic acid, ethyl butyrate, phenylethyl acetate, diethylsuccinate, hexanoic acid, and geraniol. In conclusion, we found that clear improvements could be achieved in the fermentation process with mixed, rather than pure, S. cerevisiae culture. The use of the non-Saccharomyces strain P. caribbica UFLA CAF733 in co-culture with S. cerevisiae UFLA CA11 may therefore be an interesting means by which to improve the quality of cachaça.

  10. The Effect of Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM Fermentation on Antioxidant Properties of Selected in Vitro Sprout Culture of Orthosiphon aristatus (Java Tea) as a Model Study

    Science.gov (United States)

    Hunaefi, Dase; Akumo, Divine N.; Riedel, Heidi; Smetanska, Iryna

    2012-01-01

    High rosmarinic acid (RA) productivity has been achieved by applying jasmonic acid and yeast extract elicitors to the in vitro sprout culture of Orthosiphon aritatus (IOSC). The highest RA accumulation from three solvents was detected in IOSC after treatment with yeast extract (5 g/L). HPLC analysis clearly confirmed a drastic increase in RA subjected to yeast extract elicitation. Therefore, this yeast extract elicited IOSC was chosen for a lactic acid bacteria (LAB) fermentation study as a model system. This selected IOSC was subjected to different types of LAB fermentations (Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM) for different periods of time 24, 48 and 72 h. The LAB fermentations consisted of solid state fermentations (SSF) and liquid state fermentations (LSF) in a Digital Control Unit (DCU) fermenter system. The aim was to determine the effect of fermentation on the antioxidant properties of the plant extract. Results indicated that all types of LAB fermentation decreased the level of RA and total phenolics, however, a slight increase in total flavonoids and flavonols was observed in SSF samples. HPLC results confirmed that the longer the fermentation, the greater the reduction in RA content. The highest reduction was obtained in the sample of LSF inoculated with L. plantarum for a period of 72 h. The temperature of fermentation (37 °C) was predicted as contributing to the declining level in RA content. The loss in RA was concomitant with a loss of total antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, Trolox Equivalent Antioxidant Capacity (TEAC), and Superoxide Dismutase (SOD)-like activity). These results indicate that RA is the major contributor to the antioxidant activity of this plant. PMID:26787613

  11. The Effect of Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM Fermentation on Antioxidant Properties of Selected in Vitro Sprout Culture of Orthosiphon aristatus (Java Tea as a Model Study

    Directory of Open Access Journals (Sweden)

    Dase Hunaefi

    2012-09-01

    Full Text Available High rosmarinic acid (RA productivity has been achieved by applying jasmonic acid and yeast extract elicitors to the in vitro sprout culture of Orthosiphon aritatus (IOSC. The highest RA accumulation from three solvents was detected in IOSC after treatment with yeast extract (5 g/L. HPLC analysis clearly confirmed a drastic increase in RA subjected to yeast extract elicitation. Therefore, this yeast extract elicited IOSC was chosen for a lactic acid bacteria (LAB fermentation study as a model system. This selected IOSC was subjected to different types of LAB fermentations (Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM for different periods of time 24, 48 and 72 h. The LAB fermentations consisted of solid state fermentations (SSF and liquid state fermentations (LSF in a Digital Control Unit (DCU fermenter system. The aim was to determine the effect of fermentation on the antioxidant properties of the plant extract. Results indicated that all types of LAB fermentation decreased the level of RA and total phenolics, however, a slight increase in total flavonoids and flavonols was observed in SSF samples. HPLC results confirmed that the longer the fermentation, the greater the reduction in RA content. The highest reduction was obtained in the sample of LSF inoculated with L. plantarum for a period of 72 h. The temperature of fermentation (37 °C was predicted as contributing to the declining level in RA content. The loss in RA was concomitant with a loss of total antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH scavenging activity, Trolox Equivalent Antioxidant Capacity (TEAC, and Superoxide Dismutase (SOD-like activity. These results indicate that RA is the major contributor to the antioxidant activity of this plant.

  12. Stimulation of the Megasphaera elsdenii’s butyrate production in continuous culture by a yeast additive

    Directory of Open Access Journals (Sweden)

    Oscar Soto-Cruz

    2001-06-01

    Full Text Available Continuous culture study of the ruminal bacterium Megasphaera elsdenii using lactate as carbon source is reported. Butyrate, the minor product in batch culture, was the main product in continuous culture. Under steady state conditions the biomass concentration was increased from 0.46 to 0.72 g l-1. Addition of Yea Sacc did not result an increased availability of carbon. The produced amounts of valerate and CO2 were calculated by using a combined carbon and degree of reduction balances. According to these results, the lactate catabolism of M. elsdenii was changed by the presence of yeast additive, yielding more butyrate and diminishing the production of valerate, while acetate and propionate production was not affected. Results reported in this work suggested that soluble compounds present in the yeast additive filtrate enhanced the anabolism of M. elsdenii and modified the carbon fluxes through its pathways by increasing butyrate and decreasing valerate production in continuous culture.Estudo em cultura contínua da bactéria ruminal Megasphaera elsdenii que utiliza lactato como fonte de carbono foi realizada. Butirato, foi o produto produzido em menor concentração na cultura em batelada, porém em cultura contínua foi o produto de maior concentração. Sob condições definidas a concentração de biomassa aumentou de 0.46 a 0.72 g l-1. A adição do aditivo Yea Sacc não resultou num aumento da disponibilidade do carbono. As quantidades produzidas de valerato e CO2 foram calculadas pelo uso combinado do balanço e grau de redução do carbono. De acordo com esses resultados, o catabolismo de lactato de M. elsdenii foi mudado pela adição de aditivo a base de levedura. Maior rendimento em butirato e redução na produção de valerato foi observada, por outro lado a produção deacetato e propionato não foi afetada. Os resultados desse trabalho sugerem que os componentes solúveis presentes no aditivo a base de levedura aumentam o

  13. Development of a Continuous Phytoplankton Culture System for Ocean Acidification Experiments

    Directory of Open Access Journals (Sweden)

    Cathryn Wynn-Edwards

    2014-06-01

    Full Text Available Around one third of all anthropogenic CO2 emissions have been absorbed by the oceans, causing changes in seawater pH and carbonate chemistry. These changes have the potential to affect phytoplankton, which are critically important for marine food webs and the global carbon cycle. However, our current knowledge of how phytoplankton will respond to these changes is limited to a few laboratory and mesocosm experiments. Long-term experiments are needed to determine the vulnerability of phytoplankton to enhanced pCO2. Maintaining phytoplankton cultures in exponential growth for extended periods of time is logistically difficult and labour intensive. Here we describe a continuous culture system that greatly reduces the time required to maintain phytoplankton cultures, and minimises variation in experimental pCO2 treatments over time. This system is simple, relatively cheap, flexible, and allows long-term experiments to be performed to further our understanding of chronic responses and adaptation by phytoplankton species to future ocean acidification.

  14. Adaptation of the genetically tractable malaria pathogen Plasmodium knowlesi to continuous culture in human erythrocytes

    KAUST Repository

    Moon, Robert

    2012-12-24

    Research into the aetiological agent of the most widespread form of severe malaria, Plasmodium falciparum, has benefitted enormously from the ability to culture and genetically manipulate blood-stage forms of the parasite in vitro. However, most malaria outside Africa is caused by a distinct Plasmodium species, Plasmodium vivax, and it has become increasingly apparent that zoonotic infection by the closely related simian parasite Plasmodium knowlesi is a frequent cause of life-threatening malaria in regions of southeast Asia. Neither of these important malarial species can be cultured in human cells in vitro, requiring access to primates with the associated ethical and practical constraints. We report the successful adaptation of P. knowlesi to continuous culture in human erythrocytes. Human-adapted P. knowlesi clones maintain their capacity to replicate in monkey erythrocytes and can be genetically modified with unprecedented efficiency, providing an important and unique model for studying conserved aspects of malarial biology as well as species-specific features of an emerging pathogen.

  15. Nutritional value content, biomass production and growth performance of Daphnia magna cultured with different animal wastes resulted from probiotic bacteria fermentation

    Science.gov (United States)

    Endar Herawati, Vivi; Nugroho, R. A.; Pinandoyo; Hutabarat, Johannes

    2017-02-01

    Media culture is an important factor for the growth and quality of Daphnia magna nutrient value. This study has purpose to find the increasing of nutritional content, biomass production and growth performance of D. magna using different animal wastes fermented by probiotic bacteria. This study conducted using completely randomized experimental design with 10 treatments and 3 replicates. Those media used different animal manures such as chicken manure, goat manure and quail manure mixed by rejected bread and tofu waste fermented by probiotic bacteria then cultured for 24 days. The results showed that the media which used 50% chicken manure, 100% rejected bread and 50% tofu waste created the highest biomass production, population and nutrition content of D.magna about 2111788.9 ind/L for population; 342 grams biomass production and 68.85% protein content. The highest fatty acid profile is 6.37% of linoleic and the highest essential amino acid is 22.8% of lysine. Generally, the content of ammonia, DO, temperature, and pH during the study were in the good range of D. magna’s life. This research has conclusion that media used 50% chicken manure, 100% rejected bread and 50% tofu waste created the highest biomass production, population and nutrition content of D. magna.

  16. Assessing the impact of various ensilage factors on the fermentation of grass silage using conventional culture and bacterial community analysis techniques.

    Science.gov (United States)

    McEniry, J; O'Kiely, P; Clipson, N J W; Forristal, P D; Doyle, E M

    2010-05-01

    Grass silage is an important ruminant feedstuff on farms during winter. The ensilage of grass involves a natural lactic acid bacterial fermentation under anaerobic conditions, and numerous factors can influence the outcome of preservation. The aim of this study was to investigate the effect of dry matter concentration, ensiling system, compaction and air infiltration on silage bacterial community composition. The impact of these factors was examined using conventional methods of microbial analysis and culture-independent Terminal Restriction Fragment Length Polymorphism (T-RFLP). Silage fermentation was restricted in herbage with a high dry matter concentration, and this was reflected in a shift in the bacterial population present. In contrast, ensiling system had little effect on bacterial community composition. Air infiltration, in the absence of compaction, altered silage bacterial community composition and silage pH. Dry matter concentration and the absence of compaction were the main factors affecting silage microbial community composition, and this was reflected in both the conventional culture-based and T-RFLP data. T-RFLP proved a useful tool to study the factors affecting ensilage. Apart from monitoring the presence or absence of members of the population, shifts in the relative presence of members could be monitored.

  17. Evaluation of a Multi-Parameter Sensor for Automated, Continuous Cell Culture Monitoring in Bioreactors

    Science.gov (United States)

    Pappas, D.; Jeevarajan, A.; Anderson, M. M.

    2004-01-01

    offer automated, continuous monitoring of cell cultures with a temporal resolution of 1 minute, which is not attainable by sampling via handheld blood analyzer (i-STAT). Conclusion: The resulting bias and precision found in these cell culture-based studies is comparable to Paratrend sensor clinical results. Although the large error in p02 measurements (+/-18 mm Hg) may be acceptable for clinical applications, where Paratrend values are periodically adjusted to a BGA measurement, the O2 sensor in this bundle may not be reliable enough for the single-calibration requirement of sensors used in NASA's bioreactors. The pH and pC02 sensors in the bundle are reliable and stable over the measurement period, and can be used without recalibration to measure cell cultures in rn.jcrogravity biotechnology experiments. Future work will test additional Paratrend sensors to provide statistical assessment of sensor performance.

  18. Ethanol fermentation

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    The inulin of chicory slices was hydrolyzed enzymically and fermented to ethanol. Maximum ethanol yield was achieved with fermentation combined with saccharification, using cellulase and inulinase for saccharification. The fermenting organism was Saccharomyces cerevisiae. Kluyveromyces fragilis, containing endogenous inulinase, was also used, but with lower yield.

  19. Environmental, scanning electron and optical microscope image analysis software for determining volume and occupied area of solid-state fermentation fungal cultures.

    Science.gov (United States)

    Osma, Johann F; Toca-Herrera, José L; Rodríguez-Couto, Susana

    2011-01-01

    Here we propose a software for the estimation of the occupied area and volume of fungal cultures. This software was developed using a Matlab platform and allows analysis of high-definition images from optical, electronic or atomic force microscopes. In a first step, a single hypha grown on potato dextrose agar was monitored using optical microscopy to estimate the change in occupied area and volume. Weight measurements were carried out to compare them with the estimated volume, revealing a slight difference of less than 1.5%. Similarly, samples from two different solid-state fermentation cultures were analyzed using images from a scanning electron microscope (SEM) and an environmental SEM (ESEM). Occupied area and volume were calculated for both samples, and the results obtained were correlated with the dry weight of the cultures. The difference between the estimated volume ratio and the dry weight ratio of the two cultures showed a difference of 10%. Therefore, this software is a promising non-invasive technique to determine fungal biomass in solid-state cultures.

  20. Influences of religion and culture on continuing bonds in a sample of British Muslims of Pakistani origin.

    Science.gov (United States)

    Hussein, Hanan; Oyebode, Jan R

    2009-11-01

    This study considered the nature of continuing bonds with deceased relatives in a sample of Pakistani Muslims living in the United Kingdom. Ten participants were interviewed following a cultural psychology approach and transcripts were analyzed using grounded theory methodology. Dreaming, talking with others about the deceased, following the deceased's example, keeping memories and mementos, and doing actions thought to help the deceased were forms of continued relationship found. These were intertwined with the process of grieving and were influenced by the family, culture, and religion. Religion was a strong influence on the prominence given by participants to finishing well and on the notion of doing actions thought to help the deceased. Cultural mores, such as the community, and collectivist ethos and the expectation that emotion would be expressed around the time of death, were found to be supportive for some but sources of tension for other participants. Expressing a continuing bond through following the deceased's example so as to make them proud or happy seemed to be reinforced by cultural roots in respect for elders. Participants gave instances of tensions in areas such as expression of emotion and communality versus individualism that arose as a result of their position between two cultural frameworks, some illustrating how assimilation into the host culture set up conflict with the expected norms of their family/ancestral culture. The study highlights how understanding different cultural and religious influences may enrich the concept of continuing bonds.

  1. Controlling light-use by Rhodobacter capsulatus continuous cultures in a flat-panel photobioreactor

    NARCIS (Netherlands)

    Hoekema, S.; Douma, R.D.; Janssen, M.G.J.; Tramper, J.; Wijffels, R.H.

    2006-01-01

    The main bottleneck in scale-up of phototrophic fermentation is the low efficiency of light energy conversion to the desired product, which is caused by an excessive dissipation of light energy to heat. The photoheterotrophic formation of hydrogen from acetate and light energy by the microorganism

  2. Feeder-independent continuous culture of the PICM-19 pig liver stem cell line.

    Science.gov (United States)

    Talbot, Neil C; Blomberg, Le Ann; Garrett, Wesley M; Caperna, Thomas J

    2010-10-01

    The PICM-19 pig liver stem cell line is a bipotent cell line, i.e., capable of forming either bile ductules or hepatocyte monolayers in vitro, that was derived from the primary culture of pig embryonic stem cells. The cell line has been strictly feeder-dependent in that cell replication, morphology, and function were lost if the cells were cultured without STO feeder cells. A method for the feeder-independent continuous culture of PICM-19 cells (FI-PICM-19) is presented. PICM-19 cells were maintained and grown without feeder cells on collagen I-coated tissue culture plastic for 26 passages (P26) with initial split ratios of 1:3 that diminished to split ratios of less than 1:2 after passage 16. Once plated, the FI-PICM-19 cells were overlaid with a 1:12 to 1:50 dilution of Matrigel or related extracellular matrix product. Growth of the cells was stimulated by daily refeedings with STO feeder-cell conditioned medium. The FI-PICM-19 cells grew to an approximate confluence of 50% prior to each passage at 2-wk intervals. Growth curve analysis showed their average cell number doubling time to be ~96 h. Morphologically, the feeder-independent cells closely resembled PICM-19 cells grown on feeder cells, and biliary canalicui were present at cell-to-cell junctions. However, no spontaneous multicellular ductules formed in the monolayers of FI-PICM-19 cells. Ultrastructural subcellular features of the FI-PICM-19 cells were similar to those of PICM-19 cells cultured on feeder cells. The FI-PICM-19 cells produced a spectrum of serum proteins and expressed many liver/hepatocyte-specific genes. Importantly, cytochrome P450 (EROD) activity, ammonia clearance, and urea production were maintained by the feeder-independent cells. This simple method for the propagation of the PICM-19 cell line without feeder cells should simplify the generation and selection of functional mutants within the population and enhances the cell line's potential for use in toxicological

  3. Bifurcations of a periodically forced microbial continuous culture model with restrained growth rate

    Science.gov (United States)

    Ren, Jingli; Yuan, Qigang

    2017-08-01

    A three dimensional microbial continuous culture model with a restrained microbial growth rate is studied in this paper. Two types of dilution rates are considered to investigate the dynamic behaviors of the model. For the unforced system, fold bifurcation and Hopf bifurcation are detected, and numerical simulations reveal that the system undergoes degenerate Hopf bifurcation. When the system is periodically forced, bifurcation diagrams for periodic solutions of period-one and period-two are given by researching the Poincaré map, corresponding to different bifurcation cases in the unforced system. Stable and unstable quasiperiodic solutions are obtained by Neimark-Sacker bifurcation with different parameter values. Periodic solutions of various periods can occur or disappear and even change their stability, when the Poincaré map of the forced system undergoes Neimark-Sacker bifurcation, flip bifurcation, and fold bifurcation. Chaotic attractors generated by a cascade of period doublings and some phase portraits are given at last.

  4. Enriched ammonia-tolerant methanogenic cultures as bioaugmentation inocula in continuous biomethanation processes

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Treu, Laura; Angelidaki, Irini

    2017-01-01

    Many ammonia-rich biomass sources, such as manures and protein-rich substrates, are potential inhibitors of the anaerobic digestion (AD) process. It was previously demonstrated that bioaugmentation of Methanoculleus bourgensis MS2T in an ammonia inhibited process in a continuous stirred tank...... requirements. In the current study, an enriched ammonia-tolerant methanogenic culture was bioaugmented in a CSTR reactor operating under ammonia-induced, inhibited-steady-state. The results demonstrated that bioaugmentation, completely counteracted the ammonia toxicity effect. This indicates that a commercial...... application of bioaugmentation could improve up to 36% the methane production, the greenhouse gas reduction efficiency and the gross revenue of ammonia inhibited full scale biogas reactors. 16S rRNA gene sequencing showed that bioaugmentation changed the microbial composition of the reactors resulting...

  5. Effect of starchy or fibrous carbohydrate supplementation of orchardgrass on ruminal fermentation and methane output in continuous culture

    National Research Council Canada - National Science Library

    Soder, K.J; Brito, A.F; Hafla, A.N; Rubano, M.D

    2016-01-01

    ... (Dactylis glomerata L.) with 2 levels [5 and 10% of total dry matter (DM) fed] of starchy (barley grain, BAR) or fibrous (beet pulp, BP) carbohydrate sources on nutrient digestibility, volatile fatty acid...

  6. Traditional fermented foods and beverages of Namibia

    Directory of Open Access Journals (Sweden)

    Jane Misihairabgwi

    2017-09-01

    Conclusion: Fermented foods and beverages play a major role in the diet, socioeconomic, and cultural activities of the Namibian population. Most are spontaneously fermented. Research is scarce and should be conducted on the microbiology, biochemistry, nutritional value, and safety of the fermented foods and beverages to ensure the health of the population.

  7. A comprehensive model of simultaneous denitrification and methanogenic fermentation processes.

    Science.gov (United States)

    Tugtas, A Evren; Tezel, U; Pavlostathis, Spyros G

    2010-01-01

    The denitrification process was incorporated into the IWA Anaerobic Digestion Model No. 1 (ADM1) in order to account for the effect of denitrification on the methanogenic fermentation process. The model was calibrated and optimized using previously published experimental data and kinetic parameter values obtained with a mixed, mesophilic (35 degrees C) methanogenic culture. Model simulations were used to predict the effect of nitrate reduction on the methanogenic fermentation process in batch, semi-continuous, and continuous flow reactors experiencing operational changes and/or system disturbances. The extended model clearly revealed the importance of substrate competition between denitrifiers and non-denitrifiers as well as the impact of N-oxide inhibition on process interactions between fermentation, methanogenesis, and denitrification.

  8. Influence of lactic acid bacteria, probiotic cultures and pH value in fermented yoghurt drink to sensory quality

    Directory of Open Access Journals (Sweden)

    Hana Šulcerová

    2009-01-01

    Full Text Available Nowadays, we can see on market mainly fermented milk products with addition of probiotic microorganisms, especially strains of Lactobacillus and Bifidobacterium. We can meet also other types of pro­bio­tic products. It is recommended to consume at least 100 grams of fermented milk products with mi­ni­mal concentration of 106 of probiotics in one gram or mililitr of product daily for reaching positive effect on men’s health. During fermentation of the carbohydrates, proteins and lipids are disunite and many of aromatic compounds ane compose. They give a typical sensory characteristic to fermented milk products. For quality and quantity level of probiotics, changes of pH value and sensory qua­li­ty of five kinds of fermented milk product Yoghurt Drink with different flavour were analyzed during the whole expiration period (28 days. Obtained results were statistically evaluated via the analysis of variance and the method of multiple comparison according to Tukey test (P < 0,010 and (P < 0,001. During the minimal endurance time lactic acid bacteria and Bifidobacterium sp. were evaluated and changes of descriptors and pH value were detected. Number of LAB was up to 107 CFU/ml in all samples during 28 days of analysis. Only at sample 2 the number of LAB was 106 CFU/ml. Bifidobacterium sp. grew about degree. The number of LAB and Bifidobacterium sp. of yoghurt drink correspond with public notice number 77/2003 Sb, LAB 107 nad Bifidobacterium sp. 106 KTJ / ml. During 28 days of storage the pH value decreased. The biggest pH drop was recorded between 21. and 28. days of sto­ra­ge in all samples. The beginning pH value was 4.03–4.07 and the final value was between 3.80–3.95.The results of sensory evaluation processed by analysis of dispersion according to type were statistically conlusive in descriptors thickness, texture, intensity of smell, pleasantness of taste and general impression. The results of sensory evaluation processed by

  9. Electro-Fermentation - Merging Electrochemistry with Fermentation in Industrial Applications.

    Science.gov (United States)

    Schievano, Andrea; Pepé Sciarria, Tommy; Vanbroekhoven, Karolien; De Wever, Heleen; Puig, Sebastià; Andersen, Stephen J; Rabaey, Korneel; Pant, Deepak

    2016-11-01

    Electro-fermentation (EF) merges traditional industrial fermentation with electrochemistry. An imposed electrical field influences the fermentation environment and microbial metabolism in either a reductive or oxidative manner. The benefit of this approach is to produce target biochemicals with improved selectivity, increase carbon efficiency, limit the use of additives for redox balance or pH control, enhance microbial growth, or in some cases enhance product recovery. We discuss the principles of electrically driven fermentations and how EF can be used to steer both pure culture and microbiota-based fermentations. An overview is given on which advantages EF may bring to both existing and innovative industrial fermentation processes, and which doors might be opened in waste biomass utilization towards added-value biorefineries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Pigment production and isotopic fractionations in continuous culture: okenone producing purple sulfur bacteria Part II.

    Science.gov (United States)

    Smith, D A; Steele, A; Fogel, M L

    2015-05-01

    Okenone is a carotenoid pigment unique to certain members of Chromatiaceae, the dominant family of purple sulfur bacteria (PSB) found in euxinic photic zones. Diagenetic alteration of okenone produces okenane, the only recognized molecular fossil unique to PSB. The in vivo concentrations of okenone and bacteriochlorophyll a (Bchl a) on a per cell basis were monitored and quantified as a function of light intensity in continuous cultures of the purple sulfur bacterium Marichromatium purpuratum (Mpurp1591). We show that okenone-producing PSB have constant bacteriochlorophyll to carotenoid ratios in light-harvesting antenna complexes. The in vivo concentrations of Bchl a, 0.151 ± 0.012 fmol cell(-1), and okenone, 0.103 ± 0.012 fmol cell(-1), were not dependent on average light intensity (10-225 Lux) at both steady and non-steady states. This observation revealed that in autotrophic continuous cultures of Mpurp1591, there was a constant ratio for okenone to Bchl a of 1:1.5. Okenone was therefore constitutively produced in planktonic cultures of PSB, regardless of light intensity. This confirms the legitimacy of okenone as a signature for autotrophic planktonic PSB and by extrapolation water column euxinia. We measured the δ(13)C, δ(15)N, and δ(34)S bulk biomass values from cells collected daily and determined the isotopic fractionations of Mpurp1591. There was no statistical relationship in the bulk isotope measurements or stable isotope fractionations to light intensity or cell density under steady and non-steady-state conditions. The carbon isotope fractionation between okenone and Bchl a with respect to overall bulk biomass ((13)ε pigment - biomass) was 2.2 ± 0.4‰ and -4.1 ± 0.9‰, respectively. The carbon isotopic fractionation (13ε pigment-CO2) for the production of pigments in PSB is more variable than previously thought with our reported values for okenone at -15.5 ± 1.2‰ and -21.8 ± 1.7‰ for Bchl a. © 2015 John Wiley & Sons Ltd.

  11. Identification of peptides with antioxidant and antihypertensive capacities by RP-HPLC-Q-TOF-MS in dry fermented camel sausages inoculated with different starter cultures and ripening times.

    Science.gov (United States)

    Mejri, Lobna; Vásquez-Villanueva, Romy; Hassouna, Mnasser; Marina, María Luisa; García, María Concepción

    2017-10-01

    Low molecular weight peptides are produced during meat fermentation. They contribute to generate flavor compounds but they can also exert certain bioactivities. The aim of this work was to evaluate, for the first time, the generation of bioactive peptides during the preparation of dry fermented camel sausages and to study the influence of the ripening time and the starter culture on bacteria growing, peptide concentration and size, and antioxidant and antihypertensive capacities of peptides. Camel meat sausages inoculated with different starter bacteria and non-inoculated were ripened up to 28days. Results demonstrated that bacteria population, peptide concentration, and peptide size were affected by the ripening time and the inoculated bacteria. Moreover, the ripening process resulted in an increasing antioxidant and antihypertensive capacity showing the highest bioactivities in fractions with peptides below 3kDa. Peptides in these fractions were identified by RP-HPLC-Q-TOF-MS analysis. Identified peptides showed common features with peptides with antioxidant or antihypertensive activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Effects of culture conditions on the kinetic behavior of 1,3-propanediol fermentation by Clostridium butyricum with a kinetic model.

    Science.gov (United States)

    Zhu, Chunjie; Fang, Baishan; Wang, Shizhen

    2016-07-01

    The effects of culture conditions on the kinetic behavior of 1,3-propanediol (PD) fermentation were investigated with a kinetic model. First, with initial glycerol concentration (S0) increasing, μmax and PD inhibition increased. Glycerol assimilation was harder and a little glycerol was consumed on cell maintenance at high S0. Second, with yeast extract concentration increasing, PD inhibition decreased. However, μmax decreased and glycerol assimilation became harder. It seems that the stimulus effect of yeast extract resulted from decreased PD inhibition. Glycerol amount consumed on cell maintenance also decreased. Third, with temperature decreasing, μmax and PD inhibition decreased. Glycerol assimilation was harder and a little more glycerol was consumed on cell maintenance at low temperature. Fourth, with pH increasing, μmax and PD inhibition decreased. Glycerol assimilation was harder and much more glycerol was consumed on cell maintenance at pH 6.5 and 7.5 than 7.0. This work facilitates further fermentation process optimization. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Enhancement of fructosyltransferase and fructooligosaccharides production by A. oryzae DIA-MF in Solid-State Fermentation using aguamiel as culture medium.

    Science.gov (United States)

    Muñiz-Márquez, Diana B; Contreras, Juan C; Rodríguez, Raúl; Mussatto, Solange I; Teixeira, José A; Aguilar, Cristóbal N

    2016-08-01

    The aim of this work was to improve the production of fructosyltransferase (FTase) by Solid-State Fermentation (SSF) using aguamiel (agave sap) as culture medium and Aspergillus oryzae DIA-MF as producer strain. SSF was carried out evaluating the following parameters: inoculum rate, incubation temperature, initial pH and packing density to determine the most significant factors through Box-Hunter and Hunter design. The significant factors were then further optimized using a Box-Behnken design and response surface methodology. The maximum FTase activity (1347U/L) was obtained at 32°C, using packing density of 0.7g/cm(3). Inoculum rate and initial pH had no significant influence on the response. FOS synthesis applying the enzyme produced by A. oryzae DIA-MF was also studied using aguamiel as substrate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Synergetic effects of microbial binary cultures on microbial fuel cell performance

    Science.gov (United States)

    A binary culture of Lactococcus lactis and Shewanella oneidensis was studied for an efficient conversion of glucose into electricity in a continuously-operated chemostatic electrochemical reactor. The homolactic fermentation bacterium L. lactis fermented glucose almost exclusively to lactate – the ...

  15. Evolved aniline catabolism in Acinetobacter calcoaceticus during continuous culture of river water.

    Science.gov (United States)

    Wyndham, R C

    1986-01-01

    Adaptation of Acinetobacter calcoaceticus from river water to aniline depends on the dynamics of parent and mutant populations. The parent, Acinetobacter strain DON26 phenotype Ani0, was common in river water and assimilated aniline effectively at micromolar concentrations, but was inhibited at higher concentrations of aniline. The Ani0 phenotype was also characterized by a broad specificity for oxidation of chloroanilines by aniline-induced cells. The mutant Ani+ phenotype was represented by DON2, isolated from a population of less than 100 cells ml-1 in a mixed river water culture, and by DON261, isolated during continuous culture of DON26. Ani+ strains assimilated aniline at a greater maximum specific rate than the parent and were able to grow at concentrations of aniline greater than 16 mM. These strains cooxidized phenol after growth at high aniline concentrations, but showed reduced activity toward chloroanilines. These changes plus kinetic data, oxygen uptake data, and the results of auxanography indicate that the mutant has an increased activity and altered specificity of the initial enzyme in the aniline catabolic pathway. The parent strain, DON26, was at a selective advantage relative to the mutant at low concentrations of aniline, but was replaced by the mutant when aniline concentrations increased. Adaptation of the mixed river water community to aniline involved selection of both phenotypes. Reversion of the Ani+ to Ani0 phenotype occurred at a frequency of 10(-2) in the absence of aniline selection. Plasmid content was not altered during either acquisition or loss of the Ani+ phenotype. Adaptive changes in Acinetobacter spp. populations illustrate important differences in the catabolic activities of natural and pollutant selected strains.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:3707123

  16. The Effect of LAB as Probiotic Starter Culture and Gre