Estudo do sistema ligninolitico produzido por fungos sob diferentes condições de oxigenação

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

24/02/1997

RESUMO

The ligninolytic system produced by fungi is currently of great interest because it has many environmental applications. Ligninolytic enzymes can be used for the treatment lignocellulosic wastes, biopulping, effluent treatment, etc., and one able to degrade a variety of organic pollutants. In the present work a study was made of the ligninolytic system of five fungal strains, capable of producing enzymes that participate in lignin degradation, under different conditions of oxygenation. The screening of microorganisms was made considering the results of enzymatic production in ten strains, grown in a medium containing ground Whatman n° 1 paper as the carbon source, under aerobic conditions with or without shaking and also under microaerophilic conditions. The production of celullolytic enzymes by the initial strains were also considered in the screening. Four strains of filamentous fungi LH5 (deuteromycete), 20 (deuteromycete), Q10 {Trichocladium canadense), H2 (basidiomycete) and one yeast strain LD (Geotrichum sp) were selected. These five microorganisms were grown under low oxygenation conditions in six different culture media containing as carbon sources: veratryl alcohol (0,4mM); lignosulfonic acid (0,5%); dialised lignosulfonic acid (0,5%); xylan (0,5%); sawdust (0,5%) and sugar-cane bagasse (0,5%). The production of the enzymes lignin peroxidase (LiP); manganese peroxidase (MnP); laccase; peroxidases and veratryl alcohol oxidase (VAO) revealed that in media containing veratryl alcohol, xylan, sawdust and sugar-cane bagasse, there was a better production of MnP, while in media where the lignosulfonic acid and dialysed lignosulfonic acid were used as carbon sources, the greatest production was of LiP and VAO. The microorganisms that were grown on ground Whatman n°l paper, sawdust and sugar-cane bagasse under shaking showed better production, in general, of MnP. The strains were also grown in these media primarily under shaking conditions, subsequently being under microaerophylic conditions, where an increase in the production of the enzymes LiP and VAO was observed. The demonstration of lignosulfonic acid degradation and the presence of ethanol in the enzymatic supernatant of the microorganisms grown in sawdust and in sugar-cane bagasse, were monitored by HPLC. Dialysis of the lignosulfonic acid resulted in higher degradation levels after growth of the fungi, whem compared to the non-dialysed one. The ethanol appearence in the cultures broth varied with the carbon sources sawdust or sugar-cane bagasse and also with the growth conditions used

ASSUNTO(S)

lignina microorganismos biodegradação enzimas

ACESSO AO ARTIGO

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