Isolamento e caracterização de leveduras fermentadoras de D-xilose, L-arabinose ou D-celobiose e produtoras de celulases e xilanases associadas à madeira em decomposição

• Ano de defesa: 2009
• Autor(a) principal: Raquel Miranda Cadete
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Microbiologia; Xilose; Arabinose; Celobiose; Leveduras (Fungos)
• Link de acesso: http://hdl.handle.net/1843/BUOS-8NPF8Z

Security of a sustainable energy supply providing alternatives to fossil fuels, and market demands are controlling parameters for developing new energy systems, being bioethanol a part of the solution to this problem. The aims of this study were to isolate, identify and characterize yeasts producing exoenzymes and capable of fermenting xylose, arabinose and/or cellobiose to a possible employ of thesemicroorganisms in lignocellulosic bioethanol production. A total of 585 yeasts were isolated from 89 rotting wood and 22 wood-inhabiting insects samples. In the Durham tube fermentation test, only 22 yeast strains (7 % of yeasts isolated from media with xylan or xylose) were able to ferment D-xilose; most of these strains was identified asCandida shehatae. Thirty nine yeast strains (23.4 % of yeasts isolated from carboxymethilcellulose and 42.8 % of yeasts isolated from insects) fermented cellobiose. The yeasts fermenting cellobiose were identified as belonging to the genera Candida, Pichia, Debaryomyces, Hanseniaspora and Williopsis. None yeast strain was able to ferment L-arabinose. Twenty-two yeast strains (14.2 % of yeasts isolates fromcarboxymethilcellulose) were positive to carboxymethilcellulase test and 43 (20.3 % of yeasts isolated from media with xylan and from insects) were capable do produce xylanase. Most of these producing exoenzyme strains were identified as Trichosporon spp. and Cryptococcus laurentii, respectively. Four new yeast species were found, three of them capable to ferment D-cellobiose and one fermenting D-xylose yeaststrain. The fermenting D-xylose strains Pichia stipitis IMH 43.2 and Spathaspora arborariae sp. nov. UFMG-HM 19.1a showed the best results in fermentative parameters of D-xylose conversion to ethanol. The results of this work further indicate the biotechnological potential of microorganisms obtained from rotting wood and woodinhabitinginsects in the ethanol production from lignocelulosic biomass.