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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Profiles of xylose reductase, xylitol dehydrogenase and xylitol production under different oxygen transfer volumetric coefficient values

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Autor(es):
Branco, Ricardo F. [1] ; dos Santos, Julio C. [1] ; Sarrouh, Boutros F. [1] ; Rivaldi, Juan D. [1] ; Pessoa, Jr., Adalberto [1] ; da Silva, Silvio S. [1]
Número total de Autores: 6
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Engn Sch Lorena, Dept Biotechnol, BR-12602810 Sao Paulo - Brazil
Número total de Afiliações: 1
Tipo de documento: Artigo Científico
Fonte: JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY; v. 84, n. 3, p. 326-330, 2009.
Área do conhecimento: Ciências Biológicas - Microbiologia
Citações Web of Science: 17
Assunto(s):Xilose   Xilitol   Cana-de-açúcar
Resumo

Xylitol is a sugar alcohol (polyalcohol) with many interesting properties for pharmaceutical and food products. It is currently produced by a chemical process, which has some disadvantages such as high energy requirement. Therefore microbiological production of xylitol has been studied as an alternative, but its viability is dependent on optimisation of the fermentation variables. Among these, aeration is fundamental, because xylitol is produced only under adequate oxygen availability. In most experiments with xylitol-producing yeasts, low oxygen transfer volumetric coefficient (KLa) values are used to maintain microaerobic conditions. However, in the present study the use of relatively high KLa values resulted in high xylitol production. The effect of aeration was also evaluated via the profiles of xylose reductase (XR) and xylitol dehydrogenase (XD) activities during the experiments. The highest XR specific activity (1.45 ± 0.21 U mgprotein-1) was achieved during the experiment with the lowest KLa value (12 h-1), while the highest XD specific activity (0.19 ± 0.03 U mgprotein-1) was observed with a KLa value of 25 h-1. Xylitol production was enhanced when KLa was increased from 12 to 50 h-1, which resulted in the best condition observed, corresponding to a xylitol volumetric productivity of 1.50 ± 0.08 gxylitol L-1 h-1 and an efficiency of 71 ± 6.0%. The results showed that the enzyme activities during xylitol bioproduction depend greatly on the initial KLa value (oxygen availability). This finding supplies important information for further studies in molecular biology and genetic engineering aimed at improving xylitol bioproduction. (AU)

Processo FAPESP: 08/57926-4 - Etanol: pesquisa e desenvolvimento visando ao aproveitamento integrado do bagaço de cana-de-açúcar para a produção biotecnológica do etanol lignocelulósico
Beneficiário:Silvio Silvério da Silva
Linha de fomento: Auxílio à Pesquisa - Programa BIOEN - Temático