Fermentation

Hydrogen gas, which is produced during fermentation in the human colon, is either excreted in breath or metabolised by gut bacteria through a variety of pathways. These may include methanogenesis, dissimilatory sulphate reduction, and acetogenesis. To determine which of these routes predominates in the large intestine, stools were taken from 30 healthy subjects and incubated as 5% (w/v) slurries with Lintner's starch. In 23 of 30 subjects, methane production was the main method of hydrogen disposal. In the remaining seven, high rates of sulphate reduction were recorded together with raised production of H2S. All samples showed relatively low rates of hydrogen evolution and of acetate formation from CO2 and H2. Sulphate reduction and

Consumers are becoming increasingly health conscious and therefore more discerning in their food choices. The production of fermented food products with elevated levels of B-vitamins increase both their commercial and nutritional value, and eliminate the need for subsequent fortification with these essential vitamins. Such novel products could reduce the incidence of inadequate vitamin intake which is common in many parts of the world, not only in developing countries, but also in many industrialised countries. Moreover, the concept of in situ fortification by bacterial fermentation opens the way for development of food products targeted at specific groups in society such as the elderly and adolescents. This review looks at how vitamin overproduction strategies have been developed, some of which have successfully been tested in animal models. Such innovative strategies could be relatively easily adapted by the food industry to develop novel vitamin-enhanced functional foods with enhanced consumer appeal.

Protected denomination of origin (PDO) cheeses have distinctive sensorial characteristics. They can be made only from raw milk possessing specific features, which is processed through the 'art' of the cheesemaker. In general, the distinctive sensorial traits of PDO cheese cannot be achieved under different environmental-production conditions for two main reasons: (1) some milk features are linked to specific animal production systems; (2) cheese ripening is affected by the interaction between milk (specific) and the traditional technology applied to the transformation process (non-specific). Also, the environment for a good ripening stage can be quite specific and not reproducible. With reference to milk, factors of typicality are species and/or breed, pedoclimatic conditions, animal management system and feeding. Other factors that influence cheese quality are milk treatments, milk processing and the ripening procedures. The technology applied to most cheeses currently know...

Committee in Charge 2014 ii Acknowledgements I would be remiss not to acknowledge the many people who have made this work possible, more or less chronologically: My parents, Martha Jurchak and Larry Johnson, for encouraging and pushing my intellectual, scientific, and creative development from an early age; my brother and sister, Eban and Adriana Johnson; my Grandmother, Marie Jurchak, for planting the seed of bon vivantism and supplying the younger me with plenty of cookbooks to read; to my de-facto in-laws Alice Meadows and Pete, Grace, Jack and Joe Pold for welcoming me into their family. From the early days of what would turn out to be my career, Kent Kirshenbaum, for letting me stand in the back of the room at the first Experimental Cuisine Collective meeting and giving me the space and support to start developing ideas about how to do scientific research on culinary questions; and Dave Arnold for taking my half-developed ideas seriously and giving me a lot of challenging questions about smell and chemistry to figure out. At UC Davis, my advisor, Susan Ebeler, for providing the tools and space to develop as an analytical chemist and learn the hard work of a writing, lecturing scientist, and putting up with my scientific wanderings; Hildegarde Heymann, for teaching me everything I know about sensory science and experimental design, cultivating my ideas about how science should be dealing with questions of flavor, chemistry, and cuisine, and freely offering profound words of encouragement when I needed them. Carolyn Doyle, for invaluable instrumentation help. My lab and office mates, for their support and friendship, Larry Lerno, Helene Hopfer, Ellie King, Maya Hood White and especially Anna Hjelmeland, a stalwart friend both in and outside of work. Roger Boulton, for introducing me to the technology of distilled beverages and being a valuable and enjoyably challenging presence on both my qualifying exam and dissertation committees. Alyson Mitchell and Doug Adams for their presence on my qualifying exam committee and help with academic issues and conference travel. Harold McGee, first as a role model, then as a QE committee member, and now as a dear friend and colleague. iii Related to the University of Copenhagen, Line Holler Mielby for being an early scientific role model and encouraging me to go to Denmark, Michael Bom Frøst, for enabling my coming to the Nordic Food Lab and KU, my sensory panel at KU, and Wender Bredie, Belinda Nielsen, and Charlotte Dandanell of the sensory science group.

Pectinases are the group of enzymes that catalyze the degradation of pectic substances. It has wide applications in food industries for the production and clarification of wines and juices. The aim of this study was to isolate, screen and characterize pectinase from fungi isolated from various soil samples and evaluate its application in juice clarification. Fungal strains were isolated and screened primarily using 1% citruspectin incorporated potato dextrose agar (PDA) and secondarily using pectinase screening agar medium (PSAM) for pectinolytic organisms. The enzyme was produced by submerged state fermentation and assayed using the dinitro salicylic acid (DNS) method. From 20 different soil samples, 55 fungal isolates were screened primarily and, among them, only 14 isolates were subjected for secondary screening. Out of 14, only four strains showed the highest pectinolytic activity. Among four strains, Aspergillus spp. Gm showed the highest enzyme production at a 48-h incubation ...

BACKGROUND: 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. RESULTS: 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. CONCLUSION: This study provides information on how Akpan, and other fermented yoghurt-type cereal products, could be adapted to African and European consumer preferences.

whole-plant forage crops which is based on lactic acid fermentation under anaerobic conditions, whereby lactic acid bacteria (LAB) convert watersoluble carbohydrates (WSC) into organic acids, mainly lactic acid. As a result, pH decrease and thus forage is preserved for a long time . The application of silage additives has become the conventional implement to control the ensiling process. Although the main objective in using silage additives is to ensure the fermentation process to produce well preserved silages, attention is also paid to methods of reducing ensiling losses and improving aerobic stability of silages during the feed-out period . In order to improve the ensiling process various chemical and biological Kafkas Univ Vet Fak Derg 15 (2): 195-199, 2009 DOI:10.9775/kvfd.2008.91-A RESEARCH ARTICLE

Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a method for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailor...

Hydrogen gas can be recovered from the microbial fermentation of organic substrates at high concentrations when interspecies hydrogen transfer to methanogens is prevented. Two techniques that have been used to limit methanogenesis in mixed cultures are heat treatment, to remove nonsporeforming methanogens from an inoculum, and low pH during culture growth. We found that high hydrogen gas concentrations (57-72%) were produced in all tests and that heat treatment (HT) of the inoculum (pH 6.2 or 7.5) produced greater hydrogen yields than low pH (6.2) conditions with a nonheat-treated inoculum (NHT). Conversion efficiencies of glucose to hydrogen (based on a theoretical yield of 4 mol-H 2 /mol-glucose) were as follows: 24.2% (HT, pH ) 6.2), 18.5% (HT, pH ) 7.5), 14.9% (NHT, pH ) 6.2), and 12.1% (NHT, pH ) 7.5). The main products of glucose (3 g-COD/L) utilization (g99%) in batch tests were acetate (3.4-24.1%), butyrate (6.4-29.4%), propionate (0.3-12.8%), ethanol (15.4-28.8%), and hydrogen (4.0-8.1%), with lesser amounts of acetone, propanol, and butanol (COD basis). Hydrogen gas phase concentrations in all batch cultures reached a maximum of 57-72% after 30 h but thereafter rapidly declined to nondetectable levels within 80 h. Separate experiments showed substantial hydrogen losses could occur via acetogenesis and that heat treatment did not prevent acetogenesis. Heat treatment consistently eliminated the production of measurable concentrations of methane. The disappearance of ethanol produced during hydrogen production was likely due to acetic acid production as thermodynamic calculations show that this reaction is spontaneous once hydrogen is depleted. Overall, these results show that low pH was, without heat treatment, sufficient to control hydrogen losses to methanogens in mixed batch cultures and suggest that methods will need to be found to limit acetogenesis in order to increase hydrogen gas yields by batch cultures.

Solid-state fermentation (SSF) has built up credibility in recent years in biotech industries due to its potential applications in the production of biologically active secondary metabolites, apart from feed, fuel, food, industrial chemicals and pharmaceutical products and has emerged as an attractive alternative to submerged fermentation. Bioremediation, bioleaching, biopulping, biobeneficiation, etc. are the major applications of SSF in bioprocesses which have set another milestone. Utilization of agro-industrial residues as substrates in SSF processes provides an alternative avenue and value-addition to these otherwise under-or non-utilized residues. Innovation is the key to success and it is imperative to be up-to-date with the changing demands of the industries and meet their needs for better product and services. Better understanding of biochemical engineering aspects, particularly on mathematical modeling and design of bioreactors (fermenters) has made it possible to scale-up SSF processes and some designs have been developed for commercialization, making the technology economically feasible. In future, SSF technology would be well developed at par with SmF if rationalization and standardization continues in current trend. This review describes the state-of-art scenario in totality on SSF although the focus is on the most recent developments of last 5 years or so on SSF processes and products developments.

The objective of this study is to perform a comprehensive enzyme kinetics analysis in view of validating and consolidating a semimechanistic kinetic model consisting of homogeneous and heterogeneous reactions for enzymatic hydrolysis of lignocellulosic biomass proposed by the U.S. National Renewable Energy Laboratory (Kadam et al., Biotechnol Prog 20(3):698-705, 2004) and its variations proposed in this work. A number of dedicated experiments were carried out under a range of initial conditions (Avicel® versus pretreated barley straw as substrate, different enzyme loadings and different product inhibitors such as glucose, cellobiose and xylose) to test the hydrolysis and product inhibition mechanisms of the model. A nonlinear least squares method was used to identify the model and estimate kinetic parameters based on the experimental data. The suitable mathematical model for industrial application was selected among the proposed models based on statistical information (weighted sum of square errors). The analysis showed that transglycosylation plays a key role at high glucose levels. It also showed that the values of parameters depend on the selected experimental data used for parameter estimation. Therefore, the parameter values are not universal and should be used with caution. The model proposed by Kadam et al. (Biotechnol Prog 20(3):698-705, 2004) failed to predict the hydrolysis phenomena at high glucose levels, but when combined with transglycosylation reaction(s), the prediction of cellulose hydrolysis behaviour over a broad range of substrate concentrations (50-150 g/L) and enzyme loadings (15.8-31.6 and 1-5.9 mg protein/g cellulose for Celluclast and Novozyme 188, respectively) was possible. This is the first study introducing transglycosylation into the semimechanistic model. As long as these type of models are used within the boundary of their validity (substrate type, enzyme source and substrate concentration), they can support process design and technology improvement efforts at pilot and full-scale studies.

In this study, the behaviour of Lactobacillus fermentum CRL 722 and CRL 251 were evaluated under different pH conditions (pH 6.0, 5.5, 5.0, 4.5) and without pH control. Growth was similar under all conditions assayed except at pH 4.5. These microorganisms were able to eliminate raffinose, a nondigestible α-oligosaccharide (NDO) found in soy products, showing a consumption rate of 0.25 g l −1 h −1 (pH 6.0-5.0). The removal of raffinose was due to the high α-galactosidase (α-gal) activities of these lactic acid bacteria, which was highest at pH 5.5 (5.0 U/ml). The yield of organic acids produced during raffinose consumption was also highest at this pH. The results of this study will allow selection of the optimum growth conditions of L. fermentum with elevated levels of α-gal to be used in the reduction of NDO in soy products when used as starter cultures.

MSC (Avemar) is a medical nutriment of which preclinical and observational clinical studies suggested an antimetastatic activity with no toxicity. This open-label cohort trial has compared anticancer treatments plus MSC (9 g once daily) vs anticancer treatments alone in colorectal patients, enrolled from three oncosurgical centres; cohort allocation was on the basis of patients' choice. Sixty-six colorectal cancer patients received MSC supplement for more than 6 months and 104 patients served as controls (anticancer therapies alone): no statistical difference was noted in the time from diagnosis to the last visit between the two groups. End-point analysis revealed that progression-related events were significantly less frequent in the MSC group (new recurrences: 3.0 vs 17.3%, P<0.01; new metastases: 7.6 vs 23.1%, P<0.01; deaths: 12.1 vs 31.7%, P<0.01). Survival analysis showed significant improvements in the MSC group regarding progression-free (P=0.0184) and overall su...

This experiment was carried out to study the effect of a directly fed exogenous fibrolytic enzyme on intake and digestion of DM, OM, protein, NDF, ADF, and hemicellulose of alfalfa and ryegrass hay by sheep. Four diets were randomly assigned to four ruminally cannulated lambs using a 4 × 4 Latin square design, repeated in time, with a factorial arrangement (2 × 2) of diets: 1) alfalfa hay; 2) alfalfa hay + exogenous fibrolytic enzymes (enzyme); 3) ryegrass hay; and 4) ryegrass hay + enzyme. Lambs consumed more DM and OM from alfalfa than from ryegrass hay (P < 0.001). The ADF intake was not different between the hays, but NDF intake was lower for alfalfa (P < 0.001). For both hays, the enzyme increased intake of

Humans around the globe probably discovered natural remedies against disease and cancer by trial and error over the millennia. Biomolecular archaeological analyses of ancient organics, especially plants dissolved or decocted as fermented beverages, have begun to reveal the preliterate histories of traditional pharmacopeias, which often date back thousands of years earlier than ancient textual, ethnohistorical, and ethnological evidence. In this new approach to drug discovery, two case studies from ancient Egypt and China illustrate how ancient medicines can be reconstructed from chemical and archaeological data and their active compounds delimited for testing their anticancer and other medicinal effects. Specifically, isoscopoletin from Artemisia argyi, artemisinin from Artemisia annua, and the latter&#39;s more easily assimilated semi-synthetic derivative, artesunate, showed the greatest activity in vitro against lung and colon cancers. In vivo tests of these compounds previously u...

This project aimed to develop and utilize technology on Indian mango fruit processing. Chemical properties of matured unripe and ripe Indian mangoes were determined in terms of total sugar, reducing sugar, starch, titratable acidity and pH. Fermentation parameters investigated in the study were amount of sugar added (20 and 25%) fermentation medium, acidity of fermentation medium (addition of 1.33 and 1.66 grams of citric acid for ripe and dilution of water for unripe), degree of ripening of Indian mango fruits (ripe and unripe) and ageing period (3 and 4 months). Sixteen treatments were done in triplicates and a composite sample was taken from each treatment for sensory evaluation. Results of the preference test were subjected to statistical analysis. The physicochemical properties of Indian mango wine produced using best fermentation parameters were determined. Appropriate packaging material was selected and packaging design was developed for Indian mango wine. Project cooperators were selected and the technology was transferred through training and production runs. Results of preference test showed that the wine with best sensory properties was prepared using matured unripe Indian mango diluted with water and added with 25% sugar. According to the panel of sensory experts, the taste of Indian mango wine was strong with proper blending of sweetness and sourness, its mouth feel was smooth and good balance, aroma was hot pungent and its color and appearance was clear and light yellow. Its titratable acidity was 0.622%, pH was 5, alcohol content was 11% and brix was 5°.

Hydrogen gas can be produced by electrohydrogenesis in microbial electrolysis cells (MECs) at greater yields than fermentation and at greater energy efficiencies than water electrolysis. It has been assumed that a membrane is needed in an MEC to avoid hydrogen losses due to bacterial consumption of the product gas. However, high cathodic hydrogen recoveries (78 ( 1% to 96 ( 1%) were achieved in an MEC despite the absence of a membrane between the electrodes (applied voltages of 0.3 < E ap < 0.8 V; 7.5 mS/cm solution conductivity). Through the use of a membrane-less system, a graphite fiber brush anode, and close electrode spacing, hydrogen production rates reached a maximum of 3.12 ( 0.02 m 3 H 2 /m 3 reactor per day (292 ( 1 A/m 3 ) at an applied voltage of E ap ) 0.8 V. This production rate is more than double that obtained in previous MEC studies. The energy efficiency relative to the electrical input decreased with applied voltage from 406 ( 6% (E ap ) 0.3 V) to 194 ( 2% (E ap ) 0.8 V). Overall energy efficiency relative to both E ap and energy of the substrate averaged 78 ( 4%, with a maximum of 86 ( 2% (1.02 ( 0.05 m 3 H 2 /m 3 day, E ap ) 0.4 V). At E ap ) 0.2 V, the hydrogen recovery substantially decreased, and methane concentrations increased from an average of 1.9 ( 1.3% (E ap ) 0.3-0.8 V) to 28 ( 0% of the gas, due to the long cycle time of the reactor. Increasing the solution conductivity to 20 mS/ cm increased hydrogen production rates for E ap ) 0.3-0.6 V, but consistent reactor performance could not be obtained in the high conductivity solution at E ap > 0.6 V. These results demonstrate that high hydrogen recovery and production rates are possible in a single chamber MEC without a membrane, potentially reducing the costs of these systems and allowing for new and simpler designs.

To facilitate metabolic analysis, batch fermentations of Lactobacillus rhamnosus were carried out in a new defined medium. Biomass at 10.5 g/l and lactic acid at 67 g/l with a Y P/S of 0.84 were achieved. The maximum specific growth rate and the average productivity were 0.49/h and 2.48 g/l.h, respectively. These are comparable to those of this organism and related organisms in complex media. Preliminary amino acid studies were also conducted, highlighting the importance of serine, asparagine, glutamine and cysteine. Kinetic analysis revealed that lactic acid production was predominantly growth-associated with growth associated and non-growth associated lactic acid constants of 0.389 mol/g-cell and 0.0025 mol/g-cell.h, respectively. Finally a kinetic model has been included to describe the fermentation of L. rhamnosus.

The aim of this work was to determine the effect of yeast extract and of its vitamin contents on autotrophic and heterotrophic growth and metabolism of four acetogenic bacteria from the human colon. Yeast extract exerted a stimulatory effect on autotrophic growth of the colonic acetogens, but concentration of this compound above 1-2 g. L Ϫ1 in the medium did not enhance utilization of H 2 /CO 2 . Vitamins provided by yeast extract were shown to be essential cofactors of the reductive pathway of acetate synthesis except for one Clostridium strain. Yeast extract was also necessary to maintain heterotrophic growth and acetate synthesis from glucose in acetogenic species, except in the Streptococcus strain. In the absence of yeast extract, vitamins could efficiently restore glucose fermentation via acetate. The reductive and oxidative pathways of acetate synthesis might, therefore, depend on vitamin cofactors supplied by yeast extract in most of the human acetogenic bacteria. Non-vitaminic factors appeared also to be involved in the metabolism of some of these acetogenic species.

Orientador: Marco Aurélio CremascoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuímicaResumo: O tacrolimo é um potente imunossupressor produzido por meio da fermentação por bactérias do gênero Streptomyces, sendo a Streptomyces tsukubaensis a primeira do gênero a comprovadamente produzir o tacrolimo. A maltose e a glicose foram avaliadas como fontes primárias de carbono neste trabalho, bem como a peptona de soja e licor íngreme de milho como fontes de nitrogênio. As fontes de carbono e nitrogênio foram avaliadas quanto à sua razão presentes no meio fermentativo. Ainda, com o intuito de avaliar o processo fermentativo, foram realizadas alterações de processo como, velocidade de agitação da incubadora (shaker) e temperatura de fermentação. As fermentações foram conduzidas em frascos erlenmeyer no Laboratório de Engenharia Bioquímica, Biorrefino e Produtos de Origem Renováveis, as análises analíticas foram realizadas no Laboratório de Processos de Trans...

Lignocellulosic ethanol has been considered as an alternative transportation fuel. Utilization of hemicellulosic fraction in lignocelluloses is crucial in economical production of lignocellulosic ethanol. However, this fraction has not efficiently been utilized by traditional yeast Saccharomyces cerevisiae. Genetically modified S. cerevisiae, which can utilize xylose, has several limitations including low ethanol yield, redox imbalance, and undesired metabolite formation similar to native xylose utilizing yeasts. Besides, xylose uptake is a major issue, where sugar transport system plays an important role. These genetically modified and wild-type yeast strains have further been engineered for improved xylose uptake. Various techniques have been employed to facilitate the xylose transportation in these strains. The present review is focused on the sugar transport machineries, mechanisms of xylose transport, limitations and how to deal with xylose transport for xylose assimilation in ...

The process of desalting of a proline modelling solution by electrodialysis in five-and six-chamber electrodialysis apparatus was investigated. It has been shown that the process effectively proceeded in the six-chamber device. Changes of dry substances and pH of the proline modeling solution and also voltage in a circuit in the course of the desalting process were determined depending on the current density. Kinetic curves of migration of proline through a CМ-40 membrane in the desalting process have been registered and the optimum density of a current necessary to carry out the desalting process of proline solution has been determined. Kinetic curves of the proline solution desalting have shown that in optimal and close to optimal areas of current density 99.3%, desalting of the proline solution was achieved, while with a current higher than optimal the degree of desalting of solution was about 94.6%. It was shown that the obtained relationships of the desalting process of the proline modelling solution were completely reproduced in permeate desalting during the chalk-free L-proline, L-valine and L-alanine fermentations. On the basis of the obtained results, it is possible to develop technologically accessible electrodialysis of amino acids as well as other biologically active substance desalting from cultured liquids.

To investigate the microbial and nutritional characteristics of dry feed, liquid feed containing fermented liquid cereal grains, and fermented liquid feed, and their effect on gastrointestinal ecology and growth performance, 120 piglets from 40 litters were used ...

Gasification of biomass produces a mixture of gas (mainly carbon monoxide (CO), carbon dioxide (CO 2), and hydrogen (H 2)) called synthesis gas, or syngas, by thermal degradation without combustion. Syngas can be used for heat or electricity production by thermochemical processes. This project aims at developing an alternative way to bioupgrade syngas into biogas (mainly methane), via anaerobic fermentation. Nonacclimated industrial granular sludge to be used as reactor inoculum was initially evaluated for mesophilic carboxydotrophic methanogenesis potential in batch tests at 4 and 8 mmol CO/g VSS.d, in the absence and presence of H 2 and CO 2 , respectively. Granular sludge was then introduced into a 30 L gas-lift reactor and supplied with CO, to study the production of methane and other metabolites, at different gas dilutions as well as feeding and recirculation rates. A maximal CO conversion efficiency of 75%, which was gas-liquid mass transfer limited, occurred at a CO partial pressure of 0.6 atm combined with a gas recirculation ratio of 20:1. The anaerobic granule potential for methanogenesis from CO was likely hydrogenotrophic, combined with CO-dependent H 2 formation, either under mesophilic or thermophilic conditions. Thermophilic conditions provide the anaerobic granules with a CO-bioconversion potential significantly larger (5-fold) than under mesophilic conditions, so long as the gas-liquid transfer is alleviated.

An autoclavable sensing film was developed for monitoring dissolved CO 2. The sensing film, based on fluorescence resonance energy transfer (FRET), consisted of a fluorescent donor, an acceptor, and a quaternary ammonium hydroxide, which were doped in a two-component silicone film. As no aqueous solution was used in the sensing film matrix, the sensing film was unaffected by osmotic pressure. Fluorescence lifetime was selected as the sensing parameter, and measured in frequency domain using phase fluorometry. Upon exposure to 20% CO 2-saturated water, a 43°increase in phase angle was observed at 100 MHz. The process was fully reversible when the sensing film was exposed to nitrogen-saturated water. The estimated response and recovery times for 90% signal change were 1 min (for a step change from 0 to 6.7% CO 2-saturated water) and 1.5 min (for a step change from 6.7 to 3.3% CO 2-saturated water). When used for on-line monitoring of dissolved CO 2 produced by a culture of Escherichia coli, the sensing film showed a similar trend to that obtained from off-line measurements using a wet chemistry analyzer.

Rice straw was treated with a mixed solution of acetic acid and propionic acid to enhance its biodegradability. The effect of acid concentration, pretreatment time, and the ratio of solid to liquid on the delignification performance of rice straw were investigated. It was found that the optimal conditions for hydrolysis were 0.75 mol/L acid concentration, 2 h pretreatment time and 1:20 solid to liquid ratio. Batch methane fermentation of untreated rice straw, pretreated rice straw, and the hydrolysates (the liquid fraction) of pretreatment were conducted at 35°C for 30 days, and the results indicated that methane production of rice straw can be enhanced by dilute organic acid pretreatment. Moreover, most of the acid in hydrolysates can also be converted into methane gas.

Lactose maldigestion and intolerance affect a large part of the world population. The underlying factors of lactose intolerance are not fully understood. In this review, the role of colonic metabolism is discussed, i.e. fermentation of lactose by the colonic microbiota, colonic processing of the fermentation metabolites and how these processes would play a role in the pathophysiology of lactose intolerance. We suggest that the balance between the removal and production rate of osmotic-active components (lactose, and intermediate metabolites, e.g. lactate, succinate, etc.) in the colon is a key factor in the development of symptoms. The involvement of the colon may provide the basis for designing new targeted strategies for dietary and clinical management of lactose intolerance.

Integrative flourishing stems from patterns of eating, living and engaging with the world that promote well-being and a healthy environment. For proliferating integrative flourishing, we need to explore novel, design-led collaborations for remaking artifacts and human organization. In this study, participants-cum-makers fermented their urine for a substrate in which to grow lettuce (Lactuca sativa) and thereby create a simple material relationship between their bodies and the plants. Process documentation and interviews with the twenty-two participants evaluated the key aspects that promoted their social engagement and thriving during the two-month experiment. The analysis revealed how jointly encountered technical ambiguity stimulated curiosity and how a unifying purpose promoted adaptive co-creation and mutual support. In synergetic dynamics, these factors contributed to the integrative flourishing in the waste upcycling collective. The findings indicate the importance of recursive self-regulation following interaction with an 'other.' The study outlines a systemic model for practitioners' use to orient collectivist design that positively affects environmental relationships.

Most commercial yeast strains are nonflocculent. However, controlled flocculation phenotypes could provide significant benefits to many fermentation-based industries. In nonflocculent laboratory strains, it has been demonstrated that it is possible to adjust flocculation and adhesion phenotypes to desired specifications by altering expression of the otherwise silent but dominant flocculation (FLO) genes. However, FLO genes are characterized by high allele heterogeneity and are subjected to epigenetic regulation. Extrapolation of data obtained in laboratory strains to industrial strains may therefore not always be applicable. Here, we assess the adhesion phenotypes that are associated with the expression of a chromosomal copy of the FLO1, FLO5, or FLO11 open reading frame in two nonflocculent commercial wine yeast strains, BM45 and VIN13. The chromosomal promoters of these genes were replaced with stationary phase-inducible promoters of the HSP30 and ADH2 genes. Under standard laboratory and wine making conditions, the strategy resulted in expected and stable expression patterns of these genes in both strains. However, the specific impact of the expression of individual FLO genes showed significant differences between the two wine strains and with corresponding phenotypes in laboratory strains. The data suggest that optimization of the flocculation pattern of individual commercial strains will have to be based on a strain-by-strain approach.

Different pH control agents (NaOH/H 2 SO 4 -SodSulp, NaOH/CH 3 COOH-SodAcet, NH 4 OH/CH 3 CO-OH-AmmoAcet and NH 4 OH/H 2 SO 4 -AmmoSulp) were used to investigate their effects on growth, enzyme production (alkaline protease and amylase), and entomotoxicity of Bacillus thuringiensis var. kurstaki HD-1 (Btk) against eastern spruce budworm larvae (Choristoneura fumiferana) using starch industry wastewater (SIW) as a raw material in a 15-l fermentor. AmmoSulp and SodSulp were found to be the best pH control agents for alkaline protease and amylase production, respectively; whereas, the fermented broth obtained by using SodAcet as pH control agents recorded the highest delta-endotoxin production of 1043.0 mg/l and entomotoxicity value 18.4 9 10 9 SBU/l. Entomotoxicity of re-suspended centrifuged pellet in onetenth of original volume in case of SodAcet as pH control agents was 26.7 9 10 9 SBU/l and was the highest value compared to three other pH control agents.

The present study describes citric acid fermentation by Aspergillus niger GCB-47 in a 15-l stainless steel stirred fermentor. Among the alcohols tested as stimulating agents, 1.0% (v/v) methanol was found to give maximum amount of anhydrous citric acid (90:02 AE 2:2 g/l), 24 h after inoculation. This yield of citric acid was 1.96 fold higher than the control. Methanol has a direct effect on mycelial morphology and it promotes pellet formation. It also increases the cell membrane permeability to provoke more citric acid excretion from the mycelial cells. The sugar consumed and % citric acid was 108 AE 3:8 g/l and 80:39 AE 4:5%, respectively. The desirable mycelial morphology was in the form of small round pellets having dry cell mass 14:5 AE 0:8 g/l. Addition of ethanol, however, did not found to enhance citric acid production, significantly. The maximum value of Y p=x (i.e., 5:825 AE 0:25 g/g) was observed when methanol was used as a stimulating agent. The best results of anhydrous citric acid were observed, 6 days after inoculation when the initial pH of fermentation medium was kept at 6.0.

Aims: The present investigation deals with the development of thermotolerant mutant strain of yeast for studying enhanced productivity of ethanol from molasses in a fully controlled bioreactor. Methods and Results: The parental culture of Saccharomyces cerevisiae ATCC 26602 was mutated using UV treatment. A single thermotolerant mutant was isolated after extensive screening and optimization, and grown on molasses medium in liquid cultures. The mutant was 1AE45-fold improved than its wild parent with respect to ethanol productivity (7AE2 g l )1 h )1 ), product yield (0AE44 g ethanol g )1 substrate utilized) and specific ethanol yield (19AE0 g ethanol g )1 cells). The improved ethanol productivity was directly correlated with titres of intracellular and extracellular invertase activities. The mutant supported higher volumetric and product yield of ethanol, significantly (P £ 0AE05) higher than the parental and other strains. The mutated cultures produced 1AE8-and 2AE6-fold more extracellular and intracellular invertase productivity, respectively, than that produced by its wild parent at 40°C. Thermodynamic studies revealed that the cell system exerted protection against thermal inactivation during formation of products. Conclusions: A mutant derivative of Sacchromyces cerevisiae with improved productivity of ethanol and invertases has been obtained, which showed concomitant improvement in thermostability of endogenous metabolism for formation of both ethanol and invertases. Significance and Impact of the Study: The results of the present study are of commercial value as the mutant can be used for ethanol production in parts of Pakistan where the temperature may go up to 40°C in April. Ethanol product yield coefficient and volumetric productivity, revealed the hyper-productivity of ethanol from molasses at 40°C, which is not appropriate for wild organism.

An in vitro ruminal gas production study was conducted to assess the effect of yeast supplementation on rumen fermentation of tanniniferous tropical browse mixtures prepared by mixing Berchemia discolor with Acacia brevispica, Acacia elatior, Acacia mellifera, Balanites aegyptiaca, Grewia bicolor or Zizyphus mucronata in a 1:1 dry weight ratio. The six browse mixtures were incubated with buffered rumen fluid alone or supplemented with dried Japanese Sake yeast (JSY) or polyethylene glycol (PEG). Ruminal gas production characteristics were evaluated using the Gompertz equation. The JSY addition increased gas production volume (P < 0.05) and numerically increased the maximum gas production rate constant. Time to reach the maximum gas production rate was shortened by PEG addition as compared to the JSY and control treatments. It is possible that JSY promoted the rumen microbial activity in addition to forming complexes with tannins thereby upgrading the in vitro ruminal digestion of tropical browse mixtures.

A circulating loop bioreactor (CLB) with cells immobilized in loofa sponge was constructed for simultaneous aerobic and anaerobic processes. The CLB consists of an aerated riser and a non-aerated downcomer column connected at the top and bottom by cylindrical pipes. Ethanol production from raw cassava starch was investigated in the CLB. Aspergillus awamori IAM 2389 and Saccharomyces cerevisiae IR2 immobilized on loofa sponge were placed, respectively, in the aerated riser column and non-aerated downcomer column. Both aamylase and glucoamylase activities increased as the aeration rate was increased. Ethanol yield and productivity increased with an increase in the aeration rate up to 0.5 vvm, but decreased at higher aeration rates. The CLB was operated at an aeration rate of 0.5 vvm for more than 600 h, resulting in an average ethanol productivity and yield from raw cassava starch of 0.5 g-ethanol l-1 h-1 and 0.45 g ethanol/g starch, respectively. In order to increase ethanol productivity, it was necessary to increase the dissolved oxygen (DO) concentration in the riser column and decrease the DO concentration in the downcomer column. However, increasing the aeration rate resulted in increases in the DO concentration in both the riser and the downcomer columns. At high aeration rate, there was no significant difference in the DO concentration in the riser and downcomer columns. The aeration rate was therefore uncoupled from the liquid circulation by attaching a timecontrolled valve in the upper connecting pipe. By optimizing the time and frequency of valve opening, and operation at high aeration rate, it was possible to maintain a very high DO concentration in the riser column and a low DO concentration in the downcomer column. Under these conditions, ethanol productivity increased by more than 100%, to 1.17 g l-1 h-1 .

h i g h l i g h t s Biohydrogen production using coffee mucilage and swine manure was achieved. C/N ratio around 50 could support the increase in organic load keeping stability. Repetitive batch cultivation is useful to detect changes in the pathway. Butyric and acetic pathways are the main routes in biohydrogen production.

Methods used for biosurfactant recovery include solvent extraction, precipitation, crystallization, centrifugation and foam fractionation. These methods cannot be used when distillery wastewater (DW) is used as the nutrient medium for biosurfactant production by Pseudomonas aeruginosa strain BS2, because recovery of biosurfactant by any of these methods imparts color to the biosurfactant. The biosurfactant has a nonaesthetic appearance with lowered surface active properties. These methods cannot be used for continuous recovery of biosurfactant during cultivation. Hence, a new downstream technique for biosurfactant recovery from fermented DW comprised of adsorption-desorption processes using wood-based activated carbon (WAC) was developed. This study involves batch experiments to standardize the factors affecting the rate of biosurfactant adsorption onto WAC. WAC was the most efficient adsorbent among various ones tested (i.e., silica gel, activated alumina and zeolite). The WAC (1% w v-1), equilibrium time (90 min), pH range of 5-10 and temperature of 40°C were optimum to achieve 99.5% adsorption efficiency. Adsorption kinetics and intraparticle diffusion studies revealed the involvement of both boundary layer diffusion and intraparticle diffusion. The Langmuir adsorption isotherm of WAC indicated the formation of a monolayer coverage of the biosurfactant over a homogeneous carbon surface, while the Freundlich isotherm showed high adsorption at strong solute concentrations and low adsorption at dilute solute concentrations. WAC concentration of 4% w v-1 facilitated complete removal of the biosurfactant from collapsed foam (contained 5-fold higher concentration of biosurfactant than was present in fermented DW). Biosurfactant adsorption was of chemisorption type. Acetone (polar solvent) was a specific viable eluant screened among various ones tested because it selectively facilitated maximum recovery, i.e., 89% biosurfactant from WAC. By acetone treatment, complete regeneration of WAC was feasible and WAC can be reused for biosurfactant recovery up to 3 cycles. The recovered biosurfactant showed improved surface-active property (i.e., much lower critical micelle concentration value of 0.013 verses 0.028 mg mL-1 for biosurfactant recovered by classical methods). The reuse potential of WAC was assessed and results suggest that the carbon can be reused for three consecutive cycles for biosurfactant adsorption from fermented wastewater without any decrease in adsorption efficiency. Thus, this process forms a basis for continuous recovery of biosurfactant from fermented DW and concentrated foam. This process reduces the use of high cost solvent, avoids end product inhibition and minimizes product degradation.

Previous winery-based studies showed the strains Lalvin ® RC212 (RC212) and Lalvin ® ICV-D254 (D254), when present together during fermentation, contributed to >80% relative abundance of the Saccharomyces cerevisiae population in inoculated and spontaneous fermentations. In these studies, D254 appeared to out-compete RC212, even when RC212 was used as the inoculant. In the present study, under controlled conditions, we tested the hypotheses that D254 would out-compete RC212 during fermentation and have a greater impact on key fermentation-derived chemicals. The experiment consisted of four fermentation treatments, each conducted in triplicate: a pure culture control of RC212; a pure culture control of D254; a 1:1 co-inoculation ratio of RC212:D254; and a 4:1 co-inoculation ratio of RC212:D254. Strain abundance was monitored at four stages. Inoculation ratios remained the same throughout fermentation, indicating an absence of competitive exclusion by either strain. The chemical profile of the 1:1 treatment closely resembled pure D254 fermentations, suggesting D254, under laboratory conditions, had a greater influence on the selected sensory compounds than did RC212. Nevertheless, the chemical profile of the 4:1 treatment, in which RC212 dominated, resembled that of pure RC212 fermentations. Our results support the idea that co-inoculation of strains creates a new chemical profile not seen in the pure cultures. These findings may have implications for winemakers looking to control wine aroma and flavor profiles through strain selection.

Gluconobacter oxydans converts glucose to gluconic acid and subsequently to 2-keto-D-gluconic acid (2-KGA) and 5-keto-D-gluconic acid (5-KGA) by membrane-bound periplasmic pyrroloquinoline quinone-dependent and flavin-dependent dehydrogenases. The product pattern obtained with several strains differed significantly. To increase the production of 5-KGA, which can be converted to industrially important L-(+)-tartaric acid, growth parameters were optimized. Whereas resting cells of G. oxydans ATCC 621H converted about 11% of the available glucose to 2-KGA and 6% to 5-KGA, with growing cells and improved growth under defined conditions (pH 5, 10% pO 2 , 0.05% pCO 2 ) a conversion yield of about 45% 5-KGA from the available glucose was achieved. As the accumulation of the by-product 2-KGA is highly disadvantageous for an industrial application of G. oxydans, a mutant was generated in which the membranebound gluconate-2-dehydrogenase complex was inactivated. This mutant, MF1, grew in a similar way to the wild type, but formation of the undesired 2-KGA was not observed. Under improved growth conditions, mutant MF1 converted the available glucose almost completely (84%) into 5-KGA. Therefore, this newly developed recombinant strain is suitable for the industrial production of 5-KGA.

A previously published two-dimensional discrete particle simulation model for radial mixing behavior of various slowly rotating drums for solid-state fermentation (SSF) has been extended to a three-dimensional model that also predicts axial mixing. Radial and axial mixing characteristics were predicted for three different drum designs: (1) without baf¯es; (2) with straight baf¯es; and (3) with curved baf¯es. The axial mixing behavior was studied experimentally with videoand image-analysis techniques. In the drum without baf¯es and with curved baf¯es the predicted mixing behavior matched the observed behavior adequately. The predicted axial mixing behavior in the drum with straight baf¯es was predicted less accurately, and it appeared to be strongly dependent on particle rotation, which was in contrast to the other drum designs. In the drum with curved baf¯es complete mixing in the radial and axial direction was achieved much faster than in the other designs; that is, it was already achieved after three to four rotations. This drum design may therefore be very well suited to SSF. It is concluded that discrete particle simulations provide valuable detailed knowledge about particle transport processes, and this may help to understand and optimize related heat and mass transfer processes in SSF.

The formation of hydroxystearic acid (HSA) and ketostearic acid (KSA) from oleic acid transformation has been documented in a variety of microbial species, including several isolated from the rumen of domesticated ruminant species. However, their ruminal production rates have not been established as influenced by fatty acid source. Dosing continuous cultures of mixed ruminal microorganisms with 1-(13C)-oleic acid increased the 13C enrichment of both HSA and KSA at 24 h postdosing, and showed that the majority (96 and 85%, respectively) of the HSA and KSA present in the 24-h samples originated from oleic acid. Several experiments using batch cultures of ruminal microorganisms showed that production of HSA and KSA was directly related to oleic acid input but was not affected by elaidic acid input, and that HSA was further metabolized to KSA but not to other fatty acids. When continuous cultures of ruminal microorganisms were supplemented with soybean oil or canola oil, production of 1...

Arabinoxylan-oligosaccharides (AXOS) are a recently newly discovered class of candidate prebiotics as – depending on their structure – they are fermented in different regions of gastrointestinal tract. This can have an impact on the protein/carbohydrate fermentation balance in the large intestine and, thus, affect the generation of potentially toxic metabolites in the colon originating from proteolytic activity. In this study, we screened different AXOS preparations for their impact on the in vitro intestinal fermentation activity and microbial community structure. Short-term fermentation experiments with AXOS with an average degree of polymerization (avDP) of 29 allowed part of the oligosaccharides to reach the distal colon, and decreased the concentration of proteolytic markers, whereas AXOS with lower avDP were primarily fermented in the proximal colon. Additionally, prolonged supplementation of AXOS with avDP 29 to the Simulator of Human Intestinal Microbial Ecosystem (SHIME) reactor decreased levels of the toxic proteolytic markers phenol and p-cresol in the two distal colon compartments and increased concentrations of beneficial short-chain fatty acids (SCFA) in all colon vessels (25–48%). Denaturant gradient gel electrophoresis (DGGE) analysis indicated that AXOS supplementation only slightly modified the total microbial community, implying that the observed effects on fermentation markers are mainly caused by changes in fermentation activity. Finally, specific quantitative PCR (qPCR) analysis showed that AXOS supplementation significantly increased the amount of health-promoting lactobacilli as well as of Bacteroides–Prevotella and Clostridium coccoides–Eubacterium rectale groups. These data allow concluding that AXOS are promising candidates to modulate the microbial metabolism in the distal colon.