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

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

18/08/2009

RESUMO

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 these microorganisms 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 as Candida 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 from carboxymethilcellulose) 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 yeast strain. 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 woodinhabiting insects in the ethanol production from lignocelulosic biomass.

ASSUNTO(S)

microbiologia teses. leveduras (fungos) teses. xilose decs arabinose celobiose

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