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Increased demand for biofuels promotes the search for new biomass-degrading fungi. Acremonium strictum is an environmentally widespread filamentous fungi found on plant debris; that secretes lignocellulose-degrading enzymes. A recently isolated A. strictum strain, AAJ6; native to the Brazilian Cerrado biome was evaluated for its capacity to degrade lignocellulosic substrates. In this study, whole-genome sequencing of AAJ6 was performed and 775 CAZy domains were identified which correlated to those of A. strictum strain DS1bioAY4a and other lignocellulolytic fungi; suggesting AAJ6 is a high CAZyme producer. We expressed the glycoside hydrolase families GH74 and GH3 from plasmid or genome-integrated to evaluate the ethanol production from cellulosic substrates in Brazilian industrial Saccharomyces cerevisiae strains (PE-2 and SA-1) evolved for thermotolerance (AMY12 and AMY35). Those expressing the genome-integrated enzymes showed the highest β-glucosidase activity and growth in medium with cellobiose at 40°C. The strain AGY005 (integrated cassettes) showed 19, 23 and 46% higher ethanol production in SHF, pSSF (partial hydrolysis SSF) and SSF processes, respectively, using Avicel, and ∼50% more ethanol using pre-treated sugarcane bagasse, compared to the strain with a plasmid-based expression. These results indicate the improved performance of thermotolerant industrial strains with genome-integrated CAZymes in the SSF process for 2G ethanol.

The Isopropanol-Butanol-Ethanol productivity by solventogenic clostridia can increase when cells are immobilized on low-cost, renewable fibrous materials; however, butanol inhibition imposes the need for dilute sugar solutions (less than40 g/L). To alleviate this problem, the in-situ vacuum product recovery technique was applied to recover IBE in repeated-batch cultivation of Clostridium beijerinckii DSM 6423 immobilized on sugarcane bagasse. Five repeated batch cycles were conducted in a 7-L bioreactor containing P2 medium (∼60 g/L glucose) and bagasse packed in 3D-printed concentric annular baskets. In three cycles, glucose was consumed by 86% on average, the IBE productivity was 0.35 g/L∙h or 30% and 17% higher relative to free- and immobilized (without vacuum)-cell cultures. Notably, the product stream contained 45 g/L IBE. However, the fermentation was unsatisfactory in two cycles. Finally, by inserting a fibrous bed with hollow annuli in a vacuum fermentation, this work introduces the concept of an internal-loop boiling-driven fibrous-bed bioreactor.

Mixed sugar co-fermentation represents an interesting fermentation strategy to improve bioethanol production from low-cost raw materials, such as sugarcane bagasse. The aim of this study was to evaluate a mixture of sugars (hexoses and pentoses) from sugarcane bagasse hemicellulosic hydrolysate diluted with sugarcane molasses as substrate to be converted either in monoculture or co-culture fermentations. A co-culture fermentation technique using hexoses-fermenting yeasts (Saccharomyces cerevisiae: from Santa Adelia Mill, an industrial strain (SA) and a respiratory-deficient mutant strain (ScP)) together with xylose-fermenting yeasts (Scheffersomyces stipitis (SS) and Spathaspora passalidarum (SP)) was carried out to enhance bioethanol production. Co-culture fermentation in a medium with a high mixed sugar concentration (100 g.L−1) resulted in a complete sugar consumption, ethanol titer of 30.2 g.L−1 and increased ethanol productivity (Qp =4.44 g.L−1. h−1) using wild type strains (SP + SA). In contrast, the maximum ethanol titer (49.2 g.L−1) was reached during co-culture performed with S. stipitis and the respiratory-deficient mutant strain of S. cerevisiae, however ethanol productivity (Qp =0.60 g.L−1. h−1) decreased due to the poor fermentation performance of the mutant strain. This work suggests that improved efficiency and good scalability of the mixed sugar fermentation process makes an important basis for the economic viability of bioethanol production from lignocelluloses.

Enzymatic hydrolysis of lignocellulose under industrial conditions is prone to contamination by lactic acid bacteria, and in this study, a cellulose hydrolysate produced from dilute-acid pretreatedsugarcane bagasse contained 13 g/L lactic acid and was used for IBE production by Clostridium beijerinckii DSM 6423. In fermentation of the cellulose hydrolysate supplemented with sugarcane molasses for nutrients and buffering of the medium (40 g/L total sugar), 92% of the lactic acid was consumed, and the butanol yield was as high as 0.28 (7.9 g/L butanol), suggesting that lactic acid was preferentially metabolized to butanol. When the hydrolysate was mixed with a detoxified bagasse hemicellulose hydrolysate and supplemented with molasses (35 g/L total sugar), the culture was able to exhaust glucose and utilized sucrose (by 38%), xylose (31%), and lactic acid (70%). Overall, this study shows that C. beijerinckii DSM 6423 can co-ferment first- and second-generation sugars while consuming lactic acid.

Anthocyanins were concentrated from ethanolic jussara (Euterpe edulis) extract by nanofiltration. Six commercial flat-sheet membranes with nominal molecular weight cut-off ranging from 150 to 1000 g mol−1 (NF270 and NF90 from Filmtec Dow, NP010 and NP030 from Microdyn Nadir and Desal 5-DK and Desal 5-DL from GE Osmonics) were characterized in terms of their textural properties, surface morphology and further evaluated for jussara extract nanofiltration performance. Nanofiltration trials were conducted on a stainless steel stirred dead-end cell, in which permeate fluxes were recorded by keeping operational conditions constant at 25 bar and 25 °C. N2 adsorption isotherms and atomic force microscopy images revealed a nanoporous bulk for all membranes. Changes in roughness and contact angle of membranes were observed to occur after nanofiltration trials. The Desal 5-DK membrane showed the highest efficiency for jussara extract nanofiltration due to its highest flux and smallest flux decline, in addition to the highest anthocyanins retention capacity in relation to the other commercial nanofiltration membranes.

In this work, four residual biomasses from the food industry (coconut husk, defatted grape seeds, sugar cane bagasse, and pressed palm fiber) were subjected to subcritical water hydrolysis assisted by CO2 (SubWH + CO2) with the objective of producing fermentable sugars. Hydrolysis kinetics were determined using a semi-batch unit equipped with a 50 mL reactor. The process was conducted at 250 °C for 30 min under 20 MPa. Total reducing sugars recovered using SubWH + CO2 were (wet basis): 13.5% for coconut husk, 10% for defatted grape seeds, 13.2% for sugar cane bagasse, and 11.2% for pressed palm fiber. For coconut husk and defatted grape seeds, adding CO2 increased total reducing sugars by 15 and 56%, respectively. For sugar cane bagasse and pressed palm fiber, adding CO2 to the process did not alter total reducing sugars recovered. In all cases, the byproduct yield increased when adding CO2 to the process.

Lipases from Geotrichum candidum were produced in two different medium: A = 12 % (w/v) clarified corn steep liquor (CCSL) + 0.6 % (w/v) soybean oil (SO) and B = 3.5 % (w/v) yeast hydrolysate (YH) + 0.7 % (w/v) SO. Lipases were partially purified from both media by hydrophobic interaction chromatography using 3.0 mol L−1 of NaCl as mobile phase, and they were characterized in the crude and partially purified forms. The recovery of lipase activity from CCSL and YH via HIC were 96 and 94.3 %, and the purification factors were 44.3 and 86.7-fold, respectively. All evaluated lipases had similar optimum pH (7.0–7.7), but, for the CCSL crude lipase, optimum temperature (47 °C) was 10 °C higher than others lipases evaluated. CCSL crude lipase possessed a higher thermo stability than YH crude lipase, e.g., at 37 °C (pH 7.0) the half-life of CCSL crude lipase was 19.25 h and at pH 8.0 (30 °C) the half-life was 48 h, which are five and ten times higher than with YH crude lipase, respectively. On the other hand, the YH crude lipase possessed a higher catalytic constant (kcat = 2.3 min−1) but with almost the same catalytic efficiency (Km/kcat = 32.12 mg mL min−1) in relation to CCSL crude lipase. The lipases differ in biocatalytic properties between substrates, suggesting that the two lipases can be employed for different applications.

The IBE mixture is a potential automotive fuel, and its production by Clostridium beijerinckii DSM 6423, the best known natural IBE producer, is hindered by low productivity and low butanol titer. To alleviate this problem, we cultivated C. beijerinckii DSM 6423 in repeated batches using sugarcane bagasse as a low-cost immobilization agent. Experiments were conducted in 250-mL bottles containing 150 mL P2 medium, glucose, and bagasse. In a fermentation with seven batch cycles (257 h) containing 7.5 g bagasse, glucose (60 g/L) conversion varied between 38% and 98%. In four of the batch cycles, IBE productivity was between 0.22 and 0.28 g/L∙h, and butanol titer reached 6.7–8.6 g/L. In contrast, in a free-cell single-batch cultivation, glucose conversion was limited to 35%, IBE production was slower (0.13 g IBE/L∙h), and butanol titer did not exceed 4.8 g/L. Despite the gains in productivity and butanol titer, further research is needed to elucidate the factors and mechanisms that caused IBE yield to decline during repeated-batch cultivation of C. beijerinckii DSM 6423.

BACKGROUND A new layered double hydroxide (LDH) material has been developed through a pioneering approach, with the goal of being an alternative adsorbent for the separation of biomolecules, such as clavulanic acid (CA). RESULTS Zn2Cr-CA hybrid LDH assemblies were prepared through a coprecipitation method to evaluate the affinity between the CA molecule and the interlayer sites. The resulting inorganic–organic ‘sandwich’ structure was characterized by a combination of techniques showing an expansion of the layered structure from 0.78 nm up to values of 2.30 nm upon CA intercalation. Isotherm studies were carried out to evaluate the adsorption capacity of LDH towards CA. The Freundlich adsorption model was found to fit the experimental data well, indicating a relatively large adsorption capacity for the adsorbent Zn2Cr-NO3, as high as 73.63, 128.76, and 229.62 mg1-nFLnFg−1 at 20, 30, and 35 °C, respectively. CONCLUSION Zn2Cr-NO3 adsorption capacity was not influenced by the presence of amino acids, thus underlining that it is a LDH composition which may be a suitable alternative for the separation of CA. LDH micro-particles were additionally encapsulated with calcium alginate gel (LDHME) and characterized for particle average diameter (dp = 171 µm), bulk density (ρbulk = 0.63 g cm−3), particle density (ρp = 2.2 g cm−3), particle porosity (ϵp = 0.71) and bed porosity (ϵB = 0.40). The application of LDHME in the separation of CA from complex mixtures, containing tyrosine and proline, was considered satisfactory based on purification factors of about 2.32 and degrees of purity higher than 99%. © 2015 Society of Chemical Industry

The production of an extracellular lipase using corn steep liquor (CSL) as the nitrogen source in the cultivation of Geotrichum candidum NRRLY-552 was evaluated. The optimized conditions in shake flasks were CSL, 8.0 % w/v, soybean oil, 0.6 % w/v, pH 7.0, 30 °C, 250 rpm, and 48 h, resulting in a maximum lipase productivity of 0.438 U mL−1 h−1(U = the amount of enzyme required to liberate 1 μmol of fatty acid per minute). Scale-up was evaluated with airlift and stirred tank reactors; the best conditions, respectively, were 1 vvm(volume of gas per volume of medium per minute) of aeration which resulted in 0.535 U mL−1 h−1 (32 h) and 1 vvm and 300 rpm resulting in 0.563 U mL−1 h−1 (16 h). To facilitate downstream processes, lipase production was also evaluated using CSL previously clarified with activated charcoal resulting in 0.275 U mL−1 h−1 (24 h) using 12 % (w/v) of clarified CSL in shake flasks. The obtained results showed that CSL leads to similar productivity compared to peptone using the same microorganism under similar conditions. In addition the cost of fermentation medium using CSL is much lower because it is a very inexpensive by-product from corn processing.

Pressed palm fiber (PPF), a residue obtained from palm oil industry, is a source of bioactive compounds, such as carotenoids, which are used as food additives. It also has cellulose and hemicellulose that can be used to yield fermentable sugars for the production of second generation ethanol. Supercritical fluid extraction (SFE) of pressed palm fiber provides an oil rich in carotenoids while subcritical water hydrolysis (SubWH) produces hydrolysates with high amounts of fermentable sugars. In this work, the effects of pressure (15–30 MPa) and temperature (318 and 328 K) on SFE of carotenoids were investigated. The SFE extract with highest carotenoid content was obtained at 318 K and 15 MPa (2.3% d.b., 0.81 mg β-carotene/g extract). After the extraction, the influence of process temperature (423–633 K), pressure (15 and 25 MPa), solvent:feed ratio (120 and 240), and residence time (1.25–5 min) on SubWH of the extraction residue was studied. At the temperature of 523 K, the highest total reducing sugar yield (11–23 g glucose/100 g carbohydrate) and the highest biomass conversion (40–97%) were obtained for any pressure and solvent:feed ratio. The highest selectivity for saccharide formation was found at 423 K (20–59 mol glucose/mol furfural equivalent). Optimal conditions for high saccharide formation and low sugar degradation product in subcritical hydrolysis were obtained at 523 K, 15 MPa, solvent:feed ratio of 120, residence time of 2.5 min with a total reducing sugar yield of 22.9 g glucose/100 g carbohydrate and a conversion of 84.9%.

Summary This study was aimed at using nanofiltration to purify the galactooligosaccharides (GOS) found in a commercial mixture containing lactose, glucose and galactose, whose compositions were similar to that obtained through transgalactosylation reactions catalysed by β-galactosidase from Kluyveromyces marxianus CCT 7082. NP030 polyethersulphone membrane was selected for the purification processes, once it differed statistically from other membranes due to the higher purification factor and permeate flux under the optimised temperature and pressure conditions of 35 °C and 3 MPa, respectively. Results indicate that NP030 membrane can be employed as a preliminary technique for the GOS purification with approximately 61% (w/w) of recovery.

Recent studies have shown that the chromatographic separation of mixtures of saccharides may be improved by making use of activated charcoal, a promising low cost material for the separation of sugars, including fructooligosaccharides. In this work, the development of a methodology to separate fructooligosaccharides from glucose, fructose and sucrose, using a fixed bed column packed with activated charcoal is proposed. The influence of temperature, eluant concentration and step gradients were evaluated to increase the separation efficiency and fructooligosaccharide purity. The final degree of fructooligosaccharide purification and separation efficiency were about 94% and 3.03 respectively, using ethanol gradient concentration ranging from 3.5% to 15% (v/v) at 40°C. The fixed bed column packed with the activated charcoal was shown to be a promising alternative for sugar separation, mainly those rich in fructooligosaccharides, leading to solutions of acceptable degrees of purification.

In this work, three residues from the food industry (coconut husk, defatted grape seed and pressed palm fiber) were subjected to subcritical water hydrolysis with the aim of producing fermentable sugars. Hydrolysis kinetics were determined using a semi-batch unit equipped with a 50 mL reactor. The process was conducted at 208 °C and 257 °C for 30 min, with water flow rate of 33 mL/min and under 20 MPa. The liquefaction degree of the raw materials increased with temperature. The total reducing sugars recovered also increased with temperature. Maximum total reducing sugars recovered for coconut husk, defatted grape seed and pressed palm fiber using SWH were 11.7%, 6.4% and 11.9% from total raw material, respectively. Coconut husk presented the highest amount of monosaccharides (3.4%), followed by pressed palm fiber (2.4%) and defatted grape seeds (0.7%). On the other hand, the degradation products that are also fermentation inhibitors increased with temperature as well. Each raw material presented a different monosaccharides and inhibitors profile, which indicates that SWH should be evaluated and optimized individually for each case.

Fructooligosaccharides (FOS), a well-known prebiotic product, are obtained by enzymatic synthesis and consist of a mixture of mono- and disaccharides. In this work, a methodology for their separation and purification was developed using a zeolite fixed-bed column. The effects of column temperature (40-60°C), eluent flow rate (0.10-0.14 mL/min), injected to bed volume percent ratio (2.6-5.1%), and ethanol concentration in the eluent (40-60%, v/v) were investigated using a fractionary factorial design (2(4-1)), having the separation efficiency and purity as target responses. Additional experiments were performed as well, where the temperature and ethanol concentration were studied in a central composite design (2(2)). In this work, the zeolite fixed-bed column was shown to be a good alternative for FOS purification, allowing a FOS purity of 90% and separation efficiency of 6.86 between FOS and glucose, using an eluent at 45°C with 60% ethanol concentration.

Production of butanol for fuel via the conventional Acetone-Butanol-Ethanol fermentation has been considered economically risky because of a potential oversupply of acetone. Alternatively, acetone is converted into isopropanol by specific solventogenic Clostridium species in the Isopropanol-Butanol-Ethanol (IBE) fermentation. This route, although less efficient, has been gaining attention because IBE mixtures are a potential fuel. The present work is dedicated to reviewing past and recent advances in microorganisms, feedstock, and fermentation equipment for IBE production. In our analysis we demonstrate the importance of novel engineered IBE-producing Clostridium strains and cell retention systems to decrease the staggering number of fermentation tanks required by IBE plants equipped with conventional technology. We also summarize the recent progress on recovery techniques integrated with fermentation, especially gas stripping. In addition, we assessed ongoing pilot-plant efforts that have been enabling IBE production from woody feedstock.

In this work, a subcritical water process was used for the hydrolysis of sugarcane bagasse with the aim of producing fermentable sugars. Hydrolysis kinetics was determined using a semi-batch unit equipped with a 50 mL reactor. Different sample loads (2 and 11 g), flow-rates (11, 22, 33, 44 and 55 mL/min) and temperatures (213, 251 and 290 °C) were evaluated, while maintaining constant pressure (20 MPa). The liquefaction degree of the sugarcane bagasse was not affected by water flow rate and increased with temperature; the maximum liquefaction degree was 95% for hydrolysis at 251 °C and 33 mL/min. The total reducing sugars recovered increased with flow rate up to 23%. The hydrolysis process was completed faster at higher temperatures, requiring 16 min. Maximum monosaccharides + cellobiose + cellotriose yield was 5.6% at 213 °C and 33 mL/min. Approximately 60% of the sugars recovered were in the oligomeric form.

Modelling, simulation and optimisation of the production of fructooligosaccharides (FOS) by fructosyltransferase immobilised on inorganic niobium support and applied in a basket reactor (BR) were used for in silico optimisation of the process. Simulink and MATLAB 6.0 were used as computational tools. The kinetic process data were obtained experimentally using purified fructosyltransferase produced by Rhodotula sp. Optimisation experiments were carried out using simulation, according to the factorial design methodology, using a two central composite rotatable design. In the first design, the variables with the highest influence were determined; in the second design, the conditions to produce FOS were optimised. The optimum conditions were 14 Ui/ml for the activity of enzyme, immobilised in a niobium ore, and a stirring speed of 45 rpm. Under these conditions, FOS yield was 50.6% after 24 h of synthesis, at 50°C and pH 4.5. The results demonstrated the good efficiency of the BR, as well as showing t...

This work focuses on the kinetics of ethanol production by Scheffersomyces stipitis on xylose with the development of a mathematical model considering the effect of substrate and product concentrations on growth rate. Experiments were carried out in batch and continuous modes, with substrate concentration varying from 7.2 to 145 g L−1. Inhibitory effects on cell growth, substrate uptake, and ethanol production rates were found to be considerable. Kinetic parameters were obtained through linear and non-linear regression methods. Experiments in continuous mode were performed at different dilution rates to evaluate the inhibitory effect of ethanol. A mixed mathematical model which combined Andrews and Levenspiel's models, combining substrate and product inhibition, was used. A quasi-Newton routine was applied to obtain a more accurate fitting of kinetic parameters. The parameters such as cell to product factor (Y P/X) and limiting cell yield (Y X) were shown to be dependent on substrate concentration. The kinetic model fitted satisfactorily the experimental data.

The main goal of this work was to select and characterize lipase producing wild yeasts isolated from different biomes of Brazil. A total of 372 wild yeasts were tested for their lipase producing potential and 3 strains were selected and characterized according to their substrate specificity, pH, and temperature effects and biocatalytic capacity for synthesis in organic media. For the AC02 strain, the optimal enzymatic conditions were pH 7.0 and temperature 44°C, whilst for AAV1 strain, pH 7.0 was also better, but the optimal temperature was 47°C, and for AY3 strain the optimal temperature was 37°C and pH 6.6. About substrate specificity, the lipase from AY3 strain showed higher specificity for short-chain triglycerides. The AC02 strain showed the highest lipolytic activity among the 3 selected, and was molecularly identified by sequencing the ITS1-5.8S-ITS2 and D1/D2 domains of the subunit (26 S) ribosomal DNA as Metschnikowia pulcherrima.

Background The efficient production of bioethanol by Saccharomyces cerevisiae using lignocellulosic biomass as raw material depends on the fermentability of the hydrolysates. In this work the evaluation of the kinetics of ethanol production by S. cerevisiae using enzymatic hydrolysates was performed and compared with the kinetics of diluted sugarcane molasses fermentation. Results A term for inhibition by acetic acid was added to a previous model, the kinetic parameters were re-estimated and the model has been shown to describe accurately new experiments with distinct hydrolysates proportions as fermentative media. Among all the kinetic parameters, a great reduction in μmax (from 0.437 to 0.37 h−1, at 34°C), and increment in Ypx (from 9.89 to 16.63 kg kg−1, at 34°C) were noted, which strongly affected the kinetics of fermentation. Conclusions The kinetic parameters obtained for hydrolysates differed very significantly from those obtained using molasses, which shows that models developed to describe the kinetics of first generation ethanol production need to be reformulated and adapted to describe the kinetics of second generation ethanol fermentation. The productivities achieved were between 1 and 3 kg m-3 h−1, which are considered acceptable for alcoholic fermentations in batch mode, showing the good fermentability of hydrolysates even without detoxification. © 2012 Society of Chemical Industry

This work is focussed on the evaluation of enzymatic synthesis of galactooligosaccharides (GOS) catalysed by β-galactosidase from permeabilized cell of Kluyveromyces marxianus in different compressed fluids. The experiments were performed in a batch mode reactor, where the effects of enzyme and lactose concentrations and system pressure were evaluated. Results showed significant differences in the maximum GOS concentration among the experimental conditions, where the lactose concentration and enzyme activity were found to be statistically significant. Comparing the GOS productions in the three reaction systems, the supercritical CO 2 led to the best results, where the maximum production was 83 g l −1 while, for propane and n -butane, values of 63.0 and 75.0 g l −1 were verified, respectively. According to the kinetic results of GOS production in supercritical CO 2 , a promising route is noted for this system, since the competition between synthesis and hydrolysis was less pronounced compared to the other tested fluids.

BACKGROUND: The main objective of this work was to evaluate the parametric sensitivity of model parameters of clavulanic acid (CA) adsorption in a stirred-tank reactor using zeolites. The system sensitivity was evaluated in terms of mass transfer and hydrodynamic parameters using two methodologies. First, the sensitivity factors of input variables were evaluated according to a disturbance of ±20% in the nominal parameter values; second, the factorial design methodology was employed. In both cases, the responses were obtained by means of model simulations. RESULTS:Fromthesensitivityanalysisbyexperimentaldesign,thebestoperationalconditionsforadsorptionofCAonzeolites were solid to liquid percentage 7.0%, initial CA concentration 300 mg L −1 and particle diameter 0.100 mm, which led to a reduction of 25 min in the adsorption time and 9% in the adsorption capacity, increasing the process productivity. CONCLUSION: The use of the factorial design had advantages compared with the conventional method because it provided information regarding the possibility of simultaneous changes in the factors investigated, enabling analyses of system sensitivity regarding operational parameters, as well as the choice of more suitable parameters. c � 2012 Society of Chemical Industry

Nowadays consumers seek foods that not only provide basic nutrition but also contain compounds that contribute to health. Thus, different products have been designed to meet this demand, especially those with probiotic and prebiotic characteristics. This study aimed to evaluate different formulations of a soy-based synbiotic beverage. The composition and process conditions were defined using a Placket & Burman factorial design in which the independent variables were process temperature, concentrations of the soy hydrosoluble extract and fructooligosaccharides (FOS) and the initial concentration of the probiotics Bifidobaterium longum, Lactobacillus acidophilus, Lactobacillus paracasei subsp. Paracasei, Lactobacillus rhamnosus. Changes to the product by addition of sucrose, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus were also studied. Response parameters were: pH, cell concentration (plate counting), and quantification of fructooligosaccharides, acetic acid and lactic acid. The specific growth rate (μx) and change in cell count (Δx) were determined in each formulation. The soybean hydrosoluble extract was considered a good substrate for beverage production; FOS had a greater effect at lower concentrations. At the end of all fermentation tests the total probiotic count was greater than 7 log CFU/mL, meeting the legal requirements of a functional food. Lower temperatures were better for the growth of probiotics. The addition of sucrose resulted in a lower consumption of FOS by the fermenting microorganisms, while the presence of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus represented little change concerning the evaluated characteristics. Therefore, according to the results of this study, the production of a soy-based symbiotic fermented beverage can be performed using soybean hydrosoluble extract at 10% (w/v), fructooligosaccharides at about 3% (w/v), sucrose at 12% (w/v), and the process temperature should be maintained at 35℃. Initial probiotic concentrations need not exceed 5 × 106 CFU/ml.

This work investigates the adsorption of clavulanic acid using natural six cationic forms (Na+, Ca+2, Ba+2, Sr2+, K+, and Mg2+) of the X and NZ zeolites in a stirred tank reactor since the separation is an important step of the biomolecule production. A mathematical model was proposed taking into account the transport of CA molecules from the liquid phase to the surface of the adsorbent and after diffusion into the particles. The estimated kinetic and mass transfer parameters were used to evaluate adsorption rates and mass transfer resistances involved in the separation of clavulanic acid from the broth. It has been shown that mass-transfer phenomena were a limiting step in the clavulanic acid adsorption process and that the adsorption rate should be considered to evaluate the system. Amongst the materials, the synthetic zeolite NaX was selected as the most appropriate material to separate clavulanic acid because this material presented the highest values for the observed reaction rate, compensating for the external mass transfer resistance. Modeling and simulation of clavulanic acid purification using the zeolite NaX showed a satisfactory fitting of experimental data. The model was used to simulate the process and it was evaluated for its technical and economical viability by comparisons considering the influence of the solid:liquid ratio on the adsorption equilibrium time and on the hydrolysed mass of biomolecule.

Acetone–butanol–ethanol (ABE) facilities have traditionally presented unattractive economics because of the large energy consumption during recovery of the products from a dilute fermentation broth (∼13 g/L butanol). This problem results from the high toxicity of butanol to microorganisms that catalyze its production. Flash fermentation is a continuous fermentation system with integrated product recovery. The bioreactor is operated at atmospheric pressure and the broth is circulated in a closed loop to a vacuum chamber where ABE is continuously boiled off at 37 °C and condensed afterward. With this technology the beer achieved a concentration of butanol as high as 30–37 g/L. This paper studies the energy requirements for butanol recovery using the flash fermentation technology and its effect on the energy consumption by the downstream distillation system. Compressors are used to remove the vapors from the flash tank, thus maintaining the desired vacuum. The heat recovery technique of vapor recompression i...

The aim of this study was to purify fructooligosaccharides (FOS) present in a mixture of sugars, containing also glucose, fructose and sucrose through, nanofiltration membranes. Four membranes were used: NP010 and NP030 (Microdyn Nadir, Germany), Desal−5 DL and Desal−5 HL (GE Water & Process Technologies). Experimental assays were performed in a dead-end cell and tangential cell filtration to select the most appropriate membrane. Then, with the membrane selected performed diafi ltration in tangential cell fi ltration up to a concentration about 80% FOS. In the dead-end filtration cell experiments the NP010, NP030, HL and DL membranes were selected, since they performed the highest retentions of FOS, and lowest retention of glucose. The results showed that NP030 membrane performed the highest differences between the retention of FOS and sucrose, where the retentions of the different saccharides were: fructooligosaccharides (Robs = 0.66), glucose (R obs = 0.18), fructose (R obs = 0.15) and sucrose (R obs = 0.24)...

Fructooligosaccharides (FOS) are mixtures of oligosaccharides containing mono and disaccharides, therefore, the separation of these sugars results in purer products for human consumption and can be added to various food products (drinks, cookies and yogurt). The aim of this work was the purification of fructooligosaccharides from a mixture of sugars, obtained by enzymatic synthesis, containing fructooligosaccharides, glucose, fructose and sucrose using activated charcoal fixed bed column. Temperature and ethanol concentration effects were analyzed using a 2² central composite design. Good separation conditions were obtained through central composite design. The best separation coefficient between fructooligosaccharides and glucose (ES(fructoolig/gluc)) was 3.99 ± 0.07 and between fructose and fructooligosaccharides (ES(fructoolig/fruct)) was 2.89 ± 0.36 using ethanol 15% (v/v) as eluent, at 50°C. The final FOS purification degree and recovery were about 80% and 97.8%, respectively. The activated charcoal fixed bed columns were shown to be a good alternative for sugar separation, especially for rich mixtures of fructooligosaccharides.

BACKGROUND: Fructosyltransferase synthesizes fructo-oligosaccharides from sucrose. Data used in this work were obtained by an enzyme produced by Rhodotorula sp., a microorganism isolated from fruit samples from the Brazilian Atlantic Forest, which was immobilized in an inorganic support, consisting of a niobium and graphite alloy. RESULT: All essays were conducted using enzymes at two purification grades, highly and partially purified enzymes, as comparison. The results were not significantly different between the two enzyme grades, mainly concerning the final fructo-oligossacharides yield, which were around 46%. Concerning the kinetics, the enzyme follows the Michaelis–Menten equation with inhibition by sucrose (above 60%). Also, a competitive inhibition by glucose was observed on sucrose, kestose and nystose uptakes. The immobilization of the enzyme was by ion exchange on the surface of the particles, since the support is a charged and compact solid, with negligible porosity. The mathematic model includes mass balances, considering the resistance to external mass transfer. A parameter sensitivity analysis and parameter fitting were performed by simulations and the model was validated by comparison with experimental data. CONCLUSION: The model fitted experimental data well, with deviations lower than 5% concerning FOS concentrations, indicating that it can be used in the design and control of bioreactors, either using purified or partially purified enzyme. Copyright © 2010 Society of Chemical Industry

The main conditions affecting the downstream process for purification of inulinase from Kluyveromyces marxianus var. bulgaricus ATCC 16045 were investigated. Parameters including the elution mode, linear rate, ionic strength, and elution pH were evaluated in order to achieve the best purification factor and recovery. The best purification factor and recovery were achieved in run 6 using a gradient elution mode with concentrations of NaCl ranging from 0 to 1 M, a linear flow rate of 100 cm/h and a pH value of 4.1. Under these conditions, the recovery was ∼ 67.5% and the purification factor ∼ 6.6-fold.

Recent studies have shown that the chromatographic separation of mixtures of monosaccharides and disaccharides may be improved by employing Y zeolites, a procedure which holds promise in the separation of oligosaccharides. In the present study, a column packed with zeolite was employed to study the separation of fructooligosaccharides (FOS). FOS were produced by an enzyme isolated from Rhodotorula sp., which produces GF2 (kestose), GF3 (nystose) and GF4 (frutofuranosyl nystose). The identification and quantification of the sugars were carried out by ion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The separation of fructooligosaccharides was carried out using a fixed bed column packed with Ba2+-exchange Y zeolites. The effects of temperature (40-50 degrees C), injected volume per bed volume (2.55-7.64%), superficial velocity (0.1-0.15 cm min(-1)) and eluent composition (40-60% ethanol) were investigated using a fractionary factorial design with separation efficiency as the response. The results showed that the most favorable conditions for the separation of the oligosaccharide-glucose mixture were 60% ethanol as eluent, temperature of 50 degrees C, superficial velocity of 0.1 cm min(-1) and 2.55% injection volume per bed volume of injection mixture, using two columns in series. The values for separation efficiency were 0.60 for oligosaccharide-glucose, 1.00 for oligosaccharide-fructose, 0.22 for oligosaccharide-sucrose, 0.43 for glucose-fructose, 0.82 for glucose-sucrose and 1.23 for fructose-sucrose.

Factorial design and response surface techniques were used in combination with mathematical modelling and computational simulation to optimise an innovative industrial bioprocess, the production of biobutanol employing the flash fermentation technology. A parametric analysis performed by means of a full factorial design at two levels determined the influence of operating variables on butanol yield and productivity. A second set of simulations were carried out based on the central composite rotatable design. This procedure generated simplified statistical models that describe butanol yield and productivity as functions of the significant operating variables. From these models, response surfaces were obtained and used to optimise the process. For a range of substrate concentration from 130 to 180 g/l, the optimum operating ranges ensure butanol productivity between 7.0 and 8.0 g/l h, butanol yield between 19 and 22%, substrate conversion above 90% and final butanol concentration around 25 g/l.

The development of reliable on-line state estimators applicable to reaction–separation processes is addressed in this work. Artificial Neural Network-based software sensors (ANN-SS) are proposed to allow on-line measurement of key variables, with an estimation algorithm that uses secondary variables as inputs. A continuous laboratory-scale flash fermentation for bioethanol production is considered as a case study. The process consists of three interconnected units: fermentor, filter (tangential microfiltration for cell recycling) and vacuum flash vessel (for the continuous separation of ethanol from the broth). The concentrations of ethanol in the fermentor and of ethanol condensed from the flash are successfully monitored on-line using ANN-SS. The proposed model contributes to improve the understanding of the complex relationships between process variables in the reaction and separation units, which is of major importance to allow the operation of the ethanol production process near its optimum performance.

BACKGROUND: The performance of three particle swarm optimisation (PSO) algorithms was assessed in relation to their capability to optimise an alternative fermentation process for the production of biobutanol. The process consists of three interconnected units: fermentor, cell retention system and vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). The dynamic behaviour of the process was described by a non-linear mathematical model. Four constrained optimisation problems were formulated concerning the operation and design of flash fermentation: (1) maximisation of butanol productivity; (2) maximisation of substrate conversion; (3) and (4) adjustment of operating conditions in the face of problems of fluctuations in the quality of the agricultural raw material and changes in the kinetics of the microorganisms. RESULTS: The design and operation of the flash fermentation process based on the optimisation of productivity, instead of substrate conversion, resulted in a smaller fermentor and provided satisfactory values of operating conditions able to overcome problems of variations in the glucose concentration in the raw material and changes in kinetics. CONCLUSIONS: The differences among the PSO algorithms, i.e. the velocity equation and parameters values, had significant effects on the optimisation, the best results being obtained with the original velocity equation with the inertia weight decreasing linearly with each iteration. The PSO algorithms obtained solutions that obeyed constraints, demonstrating that a constraint handling method originally developed for genetic algorithms can be applied successfully to PSO algorithms. Copyright © 2010 Society of Chemical Industry

This work presents the application of a differential distillation model for the simulation of cachaca production in a pot still (alembic). The vapor–liquid equilibria of the multicomponent mixture were described in a rigorous way, using the nonrandom two-liquid model for the liquid phase activity coefficients and the virial equation with the chemical theory for the vapor phase fugacity coefficients. Two experimental trials were performed in order to validate the simulation results. The boiling points of the wine and the ethanol concentration of the distillate were measured at fixed time intervals. The concentrations of acetaldehyde, ethyl acetate, methanol, n-propanol, isobutanol and isoamyl alcohol, and the volatile acidity were analyzed in the head, heart and tail fractions of the distillate. In general, a good agreement was achieved between the experimental and the simulation results, in terms of the temperature and the alcoholic graduation profiles, and also a satisfactory similitude in terms of the concentrations of the main congeners. PRACTICAL APPLICATIONS Spirit's sensorial quality depends on the ethanol and main congener concentrations, which should be controlled by dividing the distillate in appropriate cuts (head, heart and tail fractions) during the distillation. A correct simulation procedure of the pot still distillation allows improving the policy of distillate cuts, considering the product quality, the maximal recovery of ethanol in the heart fraction (spirit) and the energy consumption. It can as well help to define a policy of distillate cuts more appropriate to different types of wine, i.e., wines containing, for instance, larger concentrations of light components (acetaldehyde, methanol, etc.), or of those containing larger contents of heavy compounds, such as acetic acid. So this work goal was to indicate that computational simulation, based on a careful modeling of the system, could be an important tool to investigate the effect of processing variables in the final product quality, also in terms of minor compounds.

Lactic acid is an important product arising from the anaerobic fermentation of sugars. It is used in the pharmaceutical, cosmetic, chemical, and food industries as well as for biodegradable polymer and green solvent production. In this work, several bacterial strains were isolated from industrial ethanol fermentation, and the most efficient strain for lactic acid production was selected. The fermentation was conducted in a batch system under anaerobic conditions for 50 h at a temperature of 34 degrees C, a pH value of 5.0, and an initial sucrose concentration of 12 g/L using diluted sugarcane molasses. Throughout the process, pulses of molasses were added in order to avoid the cell growth inhibition due to high sugar concentration as well as increased lactic acid concentrations. At the end of the fermentation, about 90% of sucrose was consumed to produce lactic acid and cells. A kinetic model has been developed to simulate the batch lactic acid fermentation results. The data obtained from the fermentation were used for determining the kinetic parameters of the model. The developed model for lactic acid production, growth cell, and sugar consumption simulates the experimental data well.

Inulinase belongs to an important class of enzymes as it can be used to produce high-fructose syrups by enzymatic hydrolysis of inulin and fructooligosaccharides, which has been used as functional food. This work aimed to carry out a partial characterization of the crude enzymatic extract of two different inulinases, obtained by solid-state fermentation (SSF) and submerged fermentation (SmF), using agroindustrial residues as substrates. The crude enzymatic extract obtained by SmF showed an optimal pH and temperature for hydrolytic activity of 4.5 and 55 degrees Celsius, respectively; and that obtained by SSF conducted to optimal pH and temperature of 5.0 and 55 degrees Celsius, respectively. Both enzymes presented high thermostability, with a D value of 230.4 h and 123.1 h for SmF and SSF, respectively. The inulinase produced by SmF showed highest stability at pH 4.4, while inulinase obtained by SSF was more stable at pH 4.8. The results showed that inulinase obtained by SmF is less susceptible to pH effect and the inulinase obtained by SSF is more resistant to higher temperatures.

A mathematical model for an expanded bed column was developed to predict breakthrough curves for inulinase adsorption on Streamline SP ion-exchange adsorbent, using a crude fermentative broth with cells as the feedstock. The kinetics and mass transfer parameters were estimated using the PSO (particle swarm optimization) heuristic algorithm. The parameters were estimated for each expansion degree (ED) using three breakthrough curves at initial inulinase concentrations of 65.6 U mL −1 . In sequence, the model parameters for an ED of 2.5 were validated using the breakthrough curve at an initial concentration of 114.4 U mL −1 . The applicability of the validated model in process optimization was investigated, using the model as a process simulator and experimental design methodology to optimize the column and process efficiencies. The results demonstrated the usefulness of this methodology for expanded bed adsorption processes.

Cultivations of Kluyveromyces marxianus var. bulgaricus ATCC 16045 were performed on both minimal and complex media using different carbon and nitrogen sources either in the presence or absence of aeration. The results collected were worked out and compared so as to provide a useful contribution to the optimization of inulinase production. Kinetics of extracellular inulinase release were similar on glucose, fructose, and sucrose. Inulinase was detected at basal level since the beginning of batch runs on these three carbon sources and overproduced after their depletion. The highest inulinase activity in minimal medium containing 10 g/l sucrose (6.4 IU/ml) was obtained at an initial (NH(4))(2)SO(4) concentration of 5 g/l, whereas it was reduced to about one fourth of this value and detected only at the beginning under nitrogen-limited conditions. The best sucrose concentrations for the enzyme production were 30 and 20 g/l in minimal and complex media, yielding 15.4 and 208 IU/ml, respectively. In general, the enzyme activity was much higher in complex than in minimal medium under all conditions. O(2)-enriched air neither improved inulinase production nor prevented ethanol formation.