Production of xylanolytic enzymes by Penicillium janczewskii

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The production of extracellular xylanase, beta-xylosidase and alpha-L-arabinofuranosidase by the mesophilic fungus Penicillium janczewskii under submerged cultivation was investigated with different carbon sources. Optimization steps included studies of carbon source concentration, temperature of cultivation and initial pH of culture medium. The production of these enzymes was increased two times when cultures were supplemented with brewer's spent grain at 2% concentration, pH 6.0 and carried out at 25 degrees C. Under these optimized conditions were obtained xylanase activity of 15.19 U mL(-1) and 23.54 U mg prot(-1), beta-xylosidase activity of 0.16 U mL(-1) and 0.25 U mg prot(-1) and alpha-L-arabinofuranosidase activity of 0.67 U mL(-1) and 1.04 U mg prot(-1). Brewer's spent grain is a promising substrate for P. janczewskii growth and xylanolytic enzyme production, since it is the main by-product from the brewing industry, available in large amounts and at low-cost in many countries. (C) 2010 Elsevier Ltd. All rights reserved.1011141394143Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Preparation of Small Well Characterized Plutonium Oxide Reference Materials and Demonstration of the Usefulness of Such Materials for Nondestructive Analysis

Calibration of neutron coincidence and multiplicity counters for passive nondestructive analysis (NDA) of plutonium requires knowledge of the detector efficiency parameters. These are most often determined empirically. Bias from multiplication and unknown impurities may be incurred even with small plutonium metal samples. Five sets of small, pure plutonium metal standards prepared with well-known geometry and very low levels of impurities now contribute to determining accurate multiplication corrections. Recent measurements of these metal standards, with small but well-defined multiplication and negligible yield of other than fission neutrons, demonstrate an improved characterization and calibration of neutron coincidence/multiplicity counters. The precise knowledge of the mass and isotopic composition of each standard also contributes significantly to verifying the accuracy of the most precise calorimetry and gamma-ray spectroscopy measurements