Effect of oxygen transfer rate on cellulases production in stirred tank and internal-loop airlift bioreactors

In an aerobic process, such as enzymes production by fungi, the oxygen supply into fermentation medium is an important factor in order to achieve good productivities. Oxygen has an important role in metabolism and microorganism growth, being of extreme importance the control of both the dissolved oxygen transfer rate into the bioreactor and the oxygen consumption by the microorganism [1,2]. Dissolved oxygen transfer rate can be analyzed and described by means of the mass transfer coefficient, KLa, being one of the most important parameters for the design and operation of mixing/sparging of aerobic bioreactors. (…

Pretreatment of brewers' spent grains for cellulases production by Aspergillus niger van Tieghem

Successful utilization of cellulosic materials as a renewable carbon source is dependent on the development of economically feasible process technologies both for the production of biomass-degrading enzymes, and for the enzymatic hydrolysis of cellulosic materials to low molecular weight products. Significant cost reduction is required in order to enhance the commercial viability of cellulase production technology and biomass pretreatment can be an essential processing step for this purpose. Thus, the aim of this work was to evaluate the performance of pretreated brewers´ spent grains on the improvement of cellulases production by A. niger van Tieghem. For this, brewers´ spent grains was submitted to autohydrolysis treatment. Initially, the material was dried, milled and sieved (1.0 mm screen). Water was added to the sample in a closed and pressurized vessel (solid/liquid ratio 1:10 w/v), and the system heated to 180, 190 or 200ºC for 10, 35 or 50 min. The liquor obtained (hemicelluloses fraction) was separated from the solids (cellulose/lignin) by filtration and both fractions were used together or not as carbon source on fermentation: 1% (w/v) treated solid fraction; 1% (w/v) solids plus 10% (v/v) liquor, or only liquor. Carboxymethylcellulose, avicel and untreated brewers´ spent grains were used as control. The inocullum was done in Mandels medium and the cultivation conditions were 30ºC/100 rpm for 6 days. Carboxymethylcellulase (CMCase) and avicelase were assayed by DNS using 1% (w/v) carboxymethylcellulose in sodium acetate buffer, pH 4.0 and 1% (w/v) avicel in the same buffer, pH 5.0, respectivelly, while β-glucosidase was detected by p-nitrophenolate released using 5 mM pnp-β-D-glucoside in sodium citrate buffer, pH 4.5. One unit of enzymatic activity was defined as the amount that liberated 1 μmol of product per minute on assay conditions. The results showed that the liquor obtained at 190ºC/50 min autohydrolysis was quite favorable to CMCase and avicellase production, since the enzyme production was significantly higher than with other sources. However, the effect of the treatment on β-glucosidase production was not as significant as the control. These results show that by using autohydrolysis liquor as an alternative substrate, the performance of the bioprocess for cellulase production can be improved

Comparative Cr, As and CCA induced Cytostaticity in mice kidney: a contribution to assess CCA toxicity

CCA (Chromium Copper Arsenate) treated wood, widely used in outdoor residential structures and playgrounds, poses considerable dangers of leaching of its components to the environment. In this study, mouse kidney samples were used to evaluate the effects of CCA, chromium trioxide (CrO3) and arsenic pentoxide (As2O5) on cell pathophysiology by flow cytometry. Samples were collected after 14, 24, 48 and 96 h of animal exposure. While Cr had no statistically significant cytostatic effects, As2O5 induced a S-phase delay in animals exposed for 24 h, and over time a G0/G1 phase blockage. The effects of CCA in S-phase were similar, but more severe than those of As2O5. Since environmental and public health hazards due to the long durability of CCA-treated wood products, these data confirm that CCA has profoundly toxic effects on cell cycle, distinct from the compounds themselves. These cytostatic effects support cell cycle dynamics as a valuable endpoint to assess the toxicity of remaining CCA-treated infrastructures, and the expected increased waste stream over the coming decades.publishe

Evaluation of autohydrolysis process for cellulases production by Aspergillus niger van Tieghem using corncob biomass

Lignocellulosic residues, such as corncob, are a complex matrix composed by cellulose, hemicellulose and lignin that can be used for different biotechnological applications (e.g. enzymes production). However, the applications of these crude residues as substrate for enzymes production are often inefficient. An efficient hydrolysis of these residues requires a pretreatment (e.g. autohydrolysis) that lead to a more accessible structure for microorganisms attack. Recently, fungi have received significant attention as a source of new thermostable enzymes for use in many biotechnological applications, including biomass degradation (cellulases are key enzymes for efficient biomass degradation) [1]. The enzymatic degradation of cellulose to glucose is achieved by the cooperative action of endoglucanases (EC 3.1.1.4, hydrolyze randomly the internal glycosidic linkages), exoglucanases (cellobiohydrolases, CBH, EC 3.2.1.91, hydrolyze cellulose chains by removing cellobiose mainly from the non-reducing ends) and _-glucosidases (EC 3.2.1.21, cleave cellooligosaccharides and cellobiose to glucose) [2]. In this context, this work evaluates the inclusion of pretreated corncob in the nutrient media for cellulose production by Aspergillus niger van Tieghem in comparison with non-treated corncob. Autohydrolysis pretreament conditions used were 180, 190 and 200 ºC for 10, 30 and 50 min, and two fractions were obtained: solid and liquid fractions enriched by cellulose and hemicellulose, respectively. Three different mixtures (for each condition) were used as carbon source in Mandels medium [3] during the cellulases production by the A. niger van Tieghem: a solid fraction (1% w/v in medium), a liquid fraction (100 % v/v in medium), and a mixture of the solid and liquid fractions (1% w/v + 10% v/v in medium). Fermentation conditions were at 30ºC, 100 rpm, and the cellulases and _-xylosidase were quantified by Miller [4] and Kersters-Hilderson [5] methods, respectively, after 6 days of fermentation. Interestingly, the results showed that the highest cellulases production was obtained when the microorganism grows in medium containing the hemicellulose fraction (or liquid fraction) as carbon source. The exoglucanase and endoglucanase production using the liquid fraction obtained at 200ºC for 30 min, were three and twenty times higher, respectively, than the production obtained using corncob untreated, as carbon source. In relation to _-g production, the best autohydrolysis condition was 180ºC for 30 minutes; this production was fifteen percent higher than the production detected with crude corncob. This work shows the potential of autohydrolysis retreatment of lignocellulosic residues as a strategy to increase and add-value the cellulase production by filamentous fungi

Autohydrolysis pretreatment of corncob for cellulase production by Trichoderma reesei MUM 97.53

Microbial cellulase production has attracted great attention due its several applications. In this context, studies that become this practice feasible are very important. Corncob is an inexpensive byproduct, which contains more than 30% of cellulose; however, this material is not readily available to enzymatic hydrolysis and pretreatment of lignocellulosic material in autohydrolysis processes become this more easy. The inclusion of this pretreated material in the nutrient media can be a strategy to increase and undervalue cellulase production. The best pretreatment conditions for total cellulase (FPase), β-glucosidase and exoglucanase (avicelase) were obtained using the solid fraction pretreated at 200ºC for 30 or 50 minutes. It was not detected endoglucanase production (CMCase) using corncob without treatment. However, its induction was observed when T. reesei was cultivated with the corncob liquid fraction obtained after 30 minutes of pretreatment, mainly at 200ºC, where the production was maximal

Cytogenetic studies of Brazilian pediatric myelodysplastic syndrome cases: challenges and difficulties in a large and emerging country

Myelodysplastic syndromes (MDS) and juvenile myelomonocytic leukemia (JMML) are rare hematopoietic stem cell diseases affecting children. Cytogenetics plays an important role in the diagnosis of these diseases. We report here the experience of the Cytogenetic Subcommittee of the Brazilian Cooperative Group on Pediatric Myelodysplastic Syndromes (BCG-MDS-PED). We analyzed 168 cytogenetic studies performed in 23 different cytogenetic centers; 84 of these studies were performed in patients with confirmed MDS (primary MDS, secondary MDS, JMML, and acute myeloid leukemia/MDS+Down syndrome). Clonal abnormalities were found in 36.9% of the MDS cases and cytogenetic studies were important for the detection of constitutional diseases and for differential diagnosis with other myeloid neoplasms. These data show the importance of the Cooperative Group for continuing education in order to avoid a late or wrong diagnosis.Univ São Paulo, Fac Med, Dept Hematol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Hematol, São Paulo, BrazilUniv São Paulo, Fac Med, Dept Hematol, Lab Citogenet, São Paulo, BrazilUniversidade Federal de São Paulo, Inst Oncol Pediat, São Paulo, BrazilUniv Estadual Paulista, Fac Med Botucatu, Dept Clin Med, Botucatu, SP, BrazilHosp Canc Barretos, Barretos, SP, BrazilCtr Tratamento Fabiana Macedo de Morais, Grp Assistencia Crianca Canc, Grp Cooperat Brasileiro Sindrome Mielodisplas Ped, Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo, Dept Hematol, São Paulo, BrazilUniversidade Federal de São Paulo, Inst Oncol Pediat, São Paulo, BrazilWeb of Scienc

Xylanase and β‐xylosidase production: alternatives for the autohydrolysis liquor application

Fundação para a Ciência e a Tecnologia (FCT)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Production of xylanolytic enzymes by Aspergillus terricola in stirred tank and airlift tower loop bioreactors

Fungi producing high xylanase levels have attracted considerable attention because of their potential industrial applications. Batch cultivations of Aspergillus terricola fungus were evaluated in stirred tank and airlift bioreactors, by using wheat bran particles suspended in the cultivation medium as substrate for xylanase and b-xylosidase production. In the stirred tank bioreactor, in physical conditions of 30°C, 300 rpm, and aeration of 1 vvm (1 l/min), with direct inoculation of fungal spores, 7,475 U/l xylanase was obtained after 36 h of operation, remaining constant after 24 h. In the absence of air injection in the stirred tank reactor, limited xylanase production was observed (final concentration 740 U/l). When the fermentation process was realized in the airlift bioreactor, xylanase production was higher than that observed in the stirred tank bioreactor, being 9,265 U/l at 0.07 vvm (0.4 l/min) and 12,845 U/l at 0.17 vvm (1 l/min) aeration rate.Fundação para a Ciência e a Tecnologia (FCT)CNPq (Brasil)FAPESP (Brasil

Production of xylanases by Aspergillus terricola using wheat bran as carbon source : comparative studies between different bioreactors and influence of aeration and inoculum conditions

Fundação de Amparo à Pesquisa do Estado de São Paulo (Biota-FAPESP/Brazil )Fundação para a Ciência e a Tecnologia (FCT

A new strategy for xylanase production using wheat straw autohydrolysis liquor as substrate

Agro-industrial residues are lignocellulosic materials with a high content of cellulose, hemicellulose and lignin. If such residues can be produced in bioprocesses (e.g. xylanase production) there is an attractive possibility of their integral use in biotechnological processes. In general, xylanase biosynthesis is induced by its substrate – xylan, but the high xylan content of some wastes such as corn cobs and wheat bran makes them an accessible and cheap source of inducers. Another alternative to improve the xylanase production, which is the main goal of this work, is the treatment of lignocellulosic materials in autohydrolysis processes which, under optimized conditions, lead to the solubilization of hemicelluloses (liquid phase, liquor) that may be favorable to xylanase production. The inclusion of these components in the nutrient medium composition can be a strategy to optimize the microbial xylanase biosynthesis. The best conditions for xylanase production were observed when the microorganism was cultivated in birchwood xylan for 6 days; however, satisfactory results were obtained using a combination of 1% wheat bran with 2% or 10% autohydrolysis liquor, for 5 days fermentation, once the xylanase production was around 86-87% of production with xylan. Besides, the obtained production with 100% wheat straw autohydrolysis liquor was also interesting, once after 7 days of cultivation, the xylanase production was higher than the ones obtained with wheat bran or by the combination of wheat bran and liquor.Biota FAPESP (Brazil)Fundação para a Ciência e a Tecnologia (FCT