828 research outputs found
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. (…
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
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