Obtenção de inoculante e de coquetel enzimático lignocelulolítico a partir de comunidades microbianas termofílicas / Acquisition of an inoculant and a lignocellulolytic enzymatic cocktail from thermophilic microbial communities

AUTOR(ES)

Robson de Assis Souza

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

17/02/2012

RESUMO

Three thermophilic lignocellulolytic microbial communities were selected by enriched method with continual subcultivation at 55 C. One community was selected from cow manure compost, another from decaying sugar cane bagasse, and the last one was obtained by mixing aliquots of the culture suspension from the first two. Those communities were able to degrade a cellulosic strip in three cultivation days. Evaluating the maximal day of CMCase and xylanase activity, it was observed that the mixed consortium showed the best results, with CMCase activity of 0.09 U mg-1 at the second day of cultivation, and xylanase activity of 2.86 U mg-1 at the fourth day. These enzymes were partially characterized with relation to temperature and pH of optimal activity. It was observed that CMCase showed the highest activity at 60 C and pH 5.4, and kept 80% of its activity in a pH range of 4.5-6.5. On the other hand, the best activity for xylanase was verified at 65 C, and in that same pH range, the enzyme kept 97% of its residual activity. Cell-free extract was concentrated by ultrafiltration. The enzymatic cocktail obtained showed CMCase activity 25-fold higher and xylanase activity 55-fold higher than the crude enzymatic extract. The cocktail was conserved by adding 50% glycerol. After storage for 60 days at 4 C, xylanase kept 80% of the initial activity and CMCase didnt show loss of activity when kept at 25 C for the same period. The mixed community cellular mass constitutes an inoculant able to maintain the cellulolytic phenotype after rapid freezing and storage at - 80 C for 60 days. Fed-batch essay suggested that this community has potential to be manipulated in order to continuously hold the cellulolytic enzymes expression over time. The results evidenced the acquisition of an enzymatic cocktail from an inoculant which cellulolytic activity supported pH changes and optimal activity around 60 C.

ASSUNTO(S)

biorrefinaria enzimas lignocelulolíticas bagaço de cana-de-açúcar comunidade microbiana microbiologia agricola biorefinery lignocellulolytic enzymes bagasse cane sugar microbial community

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