Caracterização de celulases e xilanases produzidas por Streptomyces sp. cultivado em resíduos lignocelulósicos
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Data
2012-10-27
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Universidade Federal de Goiás
Resumo
An actinomycete strain, isolated from cane sugar bagasse (CSB), identified as
Streptomyces sp was selected for its ability to produce cellulases. The production of cellulases
was analyzed by submerged fermentation by cultivation on minimal medium (MM)
containing CSB, wheat bran (WB) or carboxymethylcellulose (CMC) as carbon source, and
yeast extract (YE) as nitrogen source. The results show that WB was the best inducer of
CMCases (2.0 U.mL-1). Aiming to analyze the production of cellulases and xylanases
kinetics, the isolate was inoculated in minimal medium containing 0.5% (w/v) WB and
maintained for 12 days at 45°C under constant agitation of 180 rpm. The highest yield of
Avicelase was observed after 264 h of cultivation (5.646 Uml-1), after 144 h for CMCase
(3.872 Uml-1), after 144 h for FPase (0.0947 Uml-1) and after 288 h for Xylanase (92.40 Uml-
1). Culture supernatants with maximum activity of Avicelase, CMCase, Fpase and Xylanase
were analyzed for optima pH and temperature of the respective enzymes. The highest enzyme
activities were detected at pH 7.0 at 35°C for Avicelase, pH 4.5/75°C for CMCase, pH
5.5/45°Cfor FPase and pH 5.5/70°C for Xylanase. The enzymes retained more than 70% of
the initial activity after 2 h incubation at 50°C. The profile proteins analyzed by zymogram
demonstrated a set of secreted cellulases (37, 21 and 17 kDa) and xylanases (39, 21, 18 and
17 kDa) when grown on FT for 144 h. The saccharification assay with CSB as substrate
showed that the enzyme complex was able to release 19% of glucose and 62.9% of xylose.
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CUNHA, Carolina Cândida de Queiroz Brito. Caracterização de celulases e xilanases produzidas por Streptomyces sp. cultivado em resíduos lignocelulósicos. 2012. 99 f. Dissertação (Mestrado em Biologia) - Universidade Federal de Goiás, Goiânia, 2012.