RESUMO
AIMS: Recombinant Aspergillus nidulans sVAL040, capable of synthesizing and secreting glucose oxidase derived from Aspergillus niger was used to study the influence of pH and carbon source on enzyme production. METHODS AND RESULTS: Glucose oxidase gene (goxC) was expressed under transcriptional regulation by using the promoter of A. nidulans xlnB gene (encoding an acidic xylanase). A maximum specific glucose oxidase activity of approx. 10 U mg(-1) protein and a maximum volumetric productivity of 29.9 U l(-1) h(-1) were obtained at pH 5.5, after 80 h of growth by using xylose as inducer. Enzyme volumetric productivity increased when xylans were used instead of xylose; however, specific glucose oxidase activity did not differ significantly. CONCLUSIONS: Specific GOX activity obtained at pH 5.5 are two to three times more than those previously described for goxC multicopy transformants of A. nidulans. Xylans were a more powerful inducer than xylose although fungal growth was lower when the polymers were used. SIGNIFICANCE AND IMPACT OF THE STUDY: The obtained results by using xlnB promoter in A. nidulans could be useful in improving heterologous enzyme production by using genetic- and process-engineering strategies.
Assuntos
Aspergillus nidulans/enzimologia , Glucose Oxidase/biossíntese , Divisão Celular , Meios de Cultura , Frutose/metabolismo , Concentração de Íons de Hidrogênio , Xilanos/metabolismo , Xilose/metabolismoRESUMO
An intergeneric osmotolerant hybrid yeast, PB2, was used together with the parental strains to study glycerol and arabitol production in batch culture. This fusion product was previously obtained by protoplast fusion between Torulaspora delbrueckii and Saccharomyces cerevisiae. Polyols and biomass production were determined in batch culture under aerobic conditions. Under the conditions tested, using PB2 hybrid and both parental strains, the best results were obtained with the hybrid. Arabitol reached a final concentration of 70 g/l and glycerol was increased to up to 50 g/l.
Assuntos
Glicerol/metabolismo , Hibridização Genética , Protoplastos/fisiologia , Saccharomycetales/metabolismo , Álcoois Açúcares/metabolismo , Meios de Cultura , Fermentação , Microbiologia Industrial/métodos , Pressão Osmótica , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Saccharomycetales/genética , Saccharomycetales/fisiologiaRESUMO
When Candida utilis was grown in continuous culture, decreasing the concentration of N in the medium affected cell composition, biomass yield, biomass productivity, maximal growth rate and cell morphology. When the dilution rate was low (0.1 h(-1)), reducing N from 1100 to 100 mg/l led to a 40% decrease in RNA content of the cells. Nitrogen-limited growth, which occurred when N<420 mg/l, was associated with significant changes in cell-wall carbohydrates and a significant reduction in the glycogen content of the cells. A set of culture conditions was established which permitted maximal consumption of the main nutrients in the medium and the production of yeast biomass suitable as a source of single-cell protein.
RESUMO
Os autores atenderam 455 casos de fraturas da face num periodo de 24 meses. A distribuicao das fraturas foi a seguinte: mandibula = 105; maxila = 25; complexo zigomatico = 141; nariz = 170 e dentoalveolares = 14. As fraturas osseas sao apresentadas e analisadas individualmente, uma vez que apresentam fisiopatologia e tratamento diferentes, apesar de manterem ligacoes entre si. O exame clinico detalhado e o exame radiografico pre-operatorio sao imprescindiveis para o planejamento cirurgico, devendo-se ter em mente que a reducao dos fragmentos osseos e a consequencia imobilizacao devem ser objetivo do tratamento