RESUMEN
Humicola grisea var. thermoidea is a deuteromycete which secretes a large spectrum of hydrolytic enzymes when grown on lignocellulosic residues. This study focused on the heterologous expression and recombinant enzyme analysis of the major secreted cellulase when the fungus is grown on sugarcane bagasse as the sole carbon source. Cellobiohydrolase 1.2 (CBH 1.2) cDNA was cloned in Pichia pastoris under control of the AOX1 promoter. Recombinant protein (rCBH1.2) was efficiently produced and secreted as a functional enzyme, presenting a molecular mass of 47 kDa. Maximum enzyme production was achieved at 96 h, in culture medium supplemented with 1.34 % urea and 1 % yeast extract and upon induction with 1 % methanol. Recombinant enzyme exhibited optimum activity at 60 °C and pH 8, and presented a remarkable thermostability, particularly at alkaline pH. Activity was evaluated on different cellulosic substrates (carboxymethyl cellulose, filter paper, microcrystalline cellulose and 4-para-nitrophenyl ß-D-glucopyranoside). Interestingly, rCBH1.2 presented both exoglucanase and endoglucanase activities and mechanical agitation increased substrate hydrolysis. Results indicate that rCBH1.2 is a potential biocatalyst for applications in the textile industry or detergent formulation.
Asunto(s)
Celulosa 1,4-beta-Celobiosidasa/metabolismo , Celulosa/metabolismo , Proteínas Fúngicas/metabolismo , Hongos Mitospóricos/metabolismo , Proteínas Recombinantes/metabolismo , Clonación Molecular/métodos , Medios de Cultivo/metabolismo , Concentración de Iones de Hidrógeno , Hidrólisis , Hongos Mitospóricos/enzimología , TemperaturaRESUMEN
PIP: The incidence of maternal mortality due to abortion was studied in the State of Sao Paulo, Brazil, in the 1970-1972 period. While mortality due to pregnancy remained relatively stable (3.38%, 3.64%, and 3.16% in the capital and 5.11%, 4.97%, and 4.28% in the rest of the State of all deaths of women of fertile age in 1970, 1971 and 1972, respectively), the incidence of abortion-related deaths among pregnancy-related deaths tended to rise (10.48%, 15.97%, and 19.13% in the capital and 9.64%, 12.42%, and 14.19% in the rest of the State, respectively). It is admitted that these data are almost certainly underestimated. It appears that the risk of death due to both pregnancy and abortion increases as age increases. The relative incidence of spontaneous and induced abortions cannot be reliably evaluated from available data, because the type of abortion rarely appears in the death certificates; however, in view of the high percentage of abortion-caused deaths preceded by infection (59.62% in the capital and 53.51% in the rest of the State), it is likely that a high percentage of deaths are the results of induced abortions. Generally, it is concluded that mortality due to abortion is relatively low, although the figures are certainly underestimates.^ieng