Caracterização de celulases e xilanases produzidas por Streptomyces sp. cultivado em resíduos lignocelulósicos

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Universidade Federal de Goiás


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.



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.