Improvement of cyclodextrin glycosyltransferase (CGTase) production by recombinant Escherichia coli pAD26 immobilized on the cotton

The cyclodextrin glycosyltransferase (CGTase) of the recombinants Escherichia coli pAD26 cells immobilized on cotton was optimally produced by statistical methodology. Primarily, carbon and nitrogen sources were selected by one-factor-at-a-time method. Wheat starch, Casamino acid, Edamin and Hy-soy were identified as the best nutrients. These sources were secondly confirmed by Plackett-Burman design (fifteen variables were studied with sixteen experiments), as the most significant components with respect to CGTase production. In the third step, concentration of most significant factors and their interaction were optimized with a Box-Behnken experimental design. Under the optimized conditions (agitation 200 rpm, yeast extract concentration 20 g/L, wheat starch concentration 10 g/L and Hy-soy concentration 2.5 g/L), CGTase yield 145.11 U/mL was 3.6 and 23 folds higher than those obtained by the use of the initial conditions (39.77 U/mL) and free cells (6.37 U/mL), respectively.     

Purification of CBS 819.72 α-amylase by aqueous two-phase systems: Modelling using Response Surface Methodology

The partition and purification of α-amylase from a culture supernatant of Aspergillus oryzae CBS 819.72 was made in aqueous two-phase system (ATPS). According to bibliography and preliminary studies, the factors polyethylene glycol (PEG) molecular weight (M_PEG) and concentration (C_PEG), buffer type (BU) and concentration (C_BU), temperature (T), salt nature (SALT) and concentration (C_SALT), bioligand (BL) and concentration (C_BL) and pH were investigated using a Plackett–Burman design to identify the factors affecting separation. Taking into consideration a simultaneous increase in enzyme recovery (R_Y) and purification factor (P_F), the best performance of the system was obtained at 4 °C and pH 6 using PEG 8000 g/mol, citrate buffer, KCl and sucrose. Experimental Box–Behnken design together with the Response Surface Methodology (RSM) have been used to find optimum C_PEG, C_Citrate and C_SALT. Quadratic models were predicted for P_F and R_Y in the top phase and a better compromise between these two parameters can be found by superimposing the contour plots of P_F and R_Y for 8% citrate. A region in the experimental space can be defined where the purification factor is always higher than 3 with yields exceeding 65%.     

Effect of Aspergillus oryzae CBS 819.72 α-amylase on rheological dough properties and bread quality

An optimum Aspergillus oryzae CBS 819.72 α-amylase production in a laboratory-scale fermentor using a wheat grinding by-product as a sole carbon source (340 U/mL) was obtained after 48 h of batch fermentation under an agitation rate of 900 rpm and a pH maintained constant for 24 h. The application of this α-amylase preparation at an adequate concentration showed positive effects on dough properties and bread quality. Extensographic analysis revealed that while this addition induced a significant increase in maximal dough resistance to extension and area below the curve (energy), it brought a substantial decrease in extensibility. Farinographic results revealed small decreases in terms of time development, water absorption, and dough stability. Bread volume was also observed to undergo a significant increase.     

Navigation and space perception assistance for the visually impaired: The NAVIG project

Navigation, especially in unknown areas, remains a major problem for the visually impaired (VI). Over the past 50 years, a number of electronic travel aids (ETAs) have been developed with the aim of improving the mobility of the VI. Despite the efforts, these systems are rarely used. Although the explanation is likely to be incomplete, it is possible to identify three important factors: (1) positioning accuracy provided by these devices is not sufficient to guide a VI pedestrian, (2) these systems are based on Geographical Information Systems not adapted to pedestrian mobility, and (3) the guidance methods should be adapted to the task of pedestrian navigation. The NAVIG project aims to answer all these limitations through a participatory design framework with the VI and orientation and mobility instructors. The NAVIG device aims to complement conventional mobility aids (i.e. white cane and guide dog), while also adding unique features to localize specific objects in the environment, restore some visuomotor abilities, and assist navigation.     

Impact of the overexpression of the StDREB1 transcription factor on growth parameters,yields, and chemical composition of tubers from greenhouse and field grown potato plants

Journal of Plant Research - Potato plants are often exposed to biotic and abiotic stresses that negatively impact their growth, development, and yield. Plants respond to different stresses by...     

PGTrust: a decentralized free-riding prevention model for DG systems

Desktop grids (DG) offer large amounts of computing power coming from internet-based volunteer networks. They suffer from the free-riding phenomenon. It may be possible for users to free ride, consuming resources donated by others but not donating any of their own. In this paper, we present PGTrust: our decentralized free-riding prevention model designed for PastryGrid. PastryGrid is a decentralized DG system which manages resources over a decentralized P2P network. PGTrust relies on the notion of score which is a metric of reputation used to evaluate the level of QoS of a peer. We have conducted out experimentations on Grid’5000 testbed. Obtained results prove the benefits of our free-riding prevention model. PGTrust is able to improve application running time by discouraging free-riders and motivating selfish peers to contribute. It offers a considerable speedup over distributed applications.