Optimization of aeration and agitation rates to improve cellulase-free xylanase production by thermotolerant Streptomyces sp. Ab106 and repeated fed-batch cultivation using agricultural waste

Thermostable cellulase-free xylanase was produced by Streptomyces sp. Ab106 using agricultural waste, sugar cane bagasse, as the substrate at 50 degrees C and pH 7.0. The central composite face-centered experimental design was applied to evaluate the optimal agitation and aeration rates in a 5-l fermentor. The highest activity (16.0+/-0.5 IU/ml) was obtained at an aeration rate of 1 vvm and an agitation rate of 150 rpm (k(L)a = 351 h(-1)). Using the repeated fed-batch cultivation technique, the maximum xylanase activity of 32+/-1 IU/ml was obtained during the second cycle of repeated fed-batch culture.     

Phase equilibrium data and thermodynamic modeling of the system propane + NMP + methanol at high pressures

This work reports phase equilibrium data at high pressures for the binary and ternary systems formed by propane + n-methyl-2-pyrrolidone (NMP) + methanol. Phase equilibrium measurements were performed in a high-pressure variable-volume view cell, following the static synthetic method for obtaining the experimental bubble and dew points transition data in the temperature range of 363-393 K, pressures up to 16 MPa and overall molar fraction of the lighter component varying from 0.1 to 0.998. For the systems investigated, vapor-liquid (VLE), liquid-liquid (LLE) and vapor-liquid-liquid (VLLE) phase transitions were visually recorded. Results show that the systems investigated present UCST (upper critical solution temperature) phase transition curves with an UCEP (upper critical end point) at a temperature higher than the propane critical temperature. The experimental data were modeled using the Peng-Robinson equation of state with the Wong-Sandler and the classical quadratic mixing rules, affording a satisfactory representation of the experimental data.     

Thermostable and alkaline-tolerant cellulase-free xylanase produced by thermotolerant Streptomyces sp. Ab106

Cellulase-free xylanase was produced by Streptomyces sp. Ab106 using cane bagasse as the substrate at 55 degrees C. Its maximum activity was 13 IU without cellulase and mannanase activities. Its profiles were investigated. Its optimum temperature and pH were 60 degrees C and 6.0, respectively. More than 70% of its activity was remained at 60 degrees C at pH 9. This enzyme was quite stable and exhibited an active of more than 70% for 144 h at 60 degrees C, and of more than 80% for 144 h at 40 degrees C, pH 9. This thermo-tolerant and alkaline-tolerant xylanase can be used in the pulp bleaching process.     

A large English–Thai parallel corpus from the web and machine-generated text

Language Resources and Evaluation - The primary objective of our work is to build a large-scale English–Thai dataset for training neural machine translation models. We construct...     

Production of xylooligosaccharides from corncob using a crude thermostable endo-xylanase from Streptomyces thermovulgaris TISTR1948 and prebiotic properties

Production of xylooligosaccharides (XOs) from corncob using the thermostable endo-xylanase from Streptomyces thermovulgaris TISTR1948 was investigated using KOH pretreatment, followed by enzymatic hydrolysis. The optimal reaction time for production of XOs was 12 h, after which xylobiose comprised a majority of products, and a low xylose content was observed. The optimal conditions for production of XOs were studied using a central composite design. At an enzyme concentration of 129.43 U/g of substrate, 53.80°C, and pH 6.17, the yield of XOs reached 162.97 mg/g of substrate or 752.15 mg/g of hemicellulose in KOH-pretreated corncob. The prebiotic properties of XOs derived from corncob were also investigated using in vitro fermentation of those XOs with the known probiotic strains Lactobacillus casei TISTR1463, L. lactis TISTR1464, and L. plantarum TISTR1465. XOs derived from corncob were comparable to commercial XOs for an ability to enhance the growth of the specified probiotic lactobacilli.