RESUMEN
Penicillium decumbens T. is an important filamentous fungus for the production of cellulases to effectively degrade lignocellulose for second generation biofuel production. In order to enhance the capability of Penicillium decumbens to produce cellulases, we constructed a creB (a deubiquitinating enzyme encoding gene) deletion cassette, and generated a creB knockout strain with homologous double crossover recombination. This mutation resulted in a detectable decrease of carbon catabolite repression (CCR) effect. The filter paper activity, endoglucanase activity, xylanase activity and exoglucanase activity of the deltacreB strain increased by 1.8, 1.71, 2.06 and 2.04 fold, respectively, when comparing with the parent strain Ku-39. A 2.68 fold increase of extracellular protein concentration was also observed. These results suggest that the deletion of creB results in CCR derepression. These data also suggest that CREB influences cellulase production of Penicillium decumbens. In generation, this study provides information that can be helpful for constructing cellulase hyper-producing strain.
Asunto(s)
Celulasa , Endopeptidasas , Genética , Metabolismo , Técnicas de Inactivación de Genes , Lignina , Metabolismo , Proteínas Mutantes , Metabolismo , Penicillium , Genética , Recombinación Genética , Proteínas Ubiquitinadas , Genética , UbiquitinaciónRESUMEN
Objective] To investigate the clinical features of amebic liver abscess, the causes of misdignosis and the effect of medical and surgical therapy on patient′s prognosis. [Methods] The clinical features of 36 patients with amebic liver abscess admitted from 1982 to 1997 in our hospital were retrospectively reviewed. [Results] The major clinical manifestations were: abdominal pain (86 1%), fever (86 1%),hepatomegaly with tenderness (83 3%) and right intercostal tenderness(58 3%). Leukocytosis was observed in 61 1%, and increased of ESR in 88 5% (23/28). Serologies against Entamoeba histolytica were noted in 92 6%. Ultrasonography showed single lesions in 75% and right\|lobe involvement in 75%. All patients were treated with metronidazole and 27 patients received treatment with needle aspiration or draining at the same time. After treatment, 10 patients were cured, 25 patients were improved significantly and effective rate was 97 2%. One patient died of hepatic failure. [Conclusion] Medical therapy alone was excellent for small abscesses, while percutaneous needle aspiration or draining was a successful approach in patients with large abscesses.