78 research outputs found
Development of a cloud radiation database for EPS-SG ICI
This document is composed of technical reports written for each of the three tasks comprising the study Development of a cloud radiation database for EPS-SG ICI. The objective of the study was the development of a cloud radiation retrieval database to be used operationally by EUMETSAT upon launch of the Ice Cloud Imager (ICI). The database will be used within the retrieval algorithm to perform retrievals of cloud ice products, including ice water path (IWP)
Xylitol production is increased by expression of codon-optimized Neurospora crassa xylose reductase gene in Candida tropicalis
Xylose reductase (XR) is the first enzyme in d-xylose metabolism, catalyzing the reduction of d-xylose to xylitol. Formation of XR in the yeast Candida tropicalis is significantly repressed in cells grown on medium that contains glucose as carbon and energy source, because of the repressive effect of glucose. This is one reason why glucose is not a suitable co-substrate for cell growth in industrial xylitol production. XR from the ascomycete Neurospora crassa (NcXR) has high catalytic efficiency; however, NcXR is not expressed in C. tropicalis because of difference in codon usage between the two species. In this study, NcXR codons were changed to those preferred in C. tropicalis. This codon-optimized NcXR gene (termed NXRG) was placed under control of a constitutive glyceraldehyde-3-phosphate dehydrogenase (GAPDH) promoter derived from C. tropicalis, and integrated into the genome of xylitol dehydrogenase gene (XYL2)-disrupted C. tropicalis. High expression level of NXRG was confirmed by determining XR activity in cells grown on glucose medium. The resulting recombinant strain, LNG2, showed high XR activity (2.86 U (mg of protein)â1), whereas parent strain BSXDH-3 showed no activity. In xylitol fermentation using glucose as a co-substrate with xylose, LNG2 showed xylitol production rate 1.44 g Lâ1 hâ1 and xylitol yield of 96% at 44 h, which were 73 and 62%, respectively, higher than corresponding values for BSXDH-3 (rate 0.83 g Lâ1 hâ1; yield 59%)
L-lactic acid production from D-xylose with Candida sonorensis expressing a heterologous lactate dehydrogenase encoding gene
Data-driven configuration recommendation for microwave networks A comparison of machine learning approaches for the recommendation of configurations and the detection of configuration anomalies
As mobile networks grow and the demand for faster connections and a better reachability
increases, telecommunication providers are looking ahead to an increasing
effort to maintain and plan their networks. It is therefore of interest to avoid manual
maintenance and planning of mobile networks and look into possibilities to help
automate such processes. The planning and configuration of microwave link networks
involves manual steps resulting in an increased effort for maintenance and
the risk of manual mistakes. We therefore investigate the usage of the networkâs
data to train machine learning models that predict a linkâs configuration setting
for given information of its surroundings, and to give configuration recommendations
for possible misconfigurations. The results show that the available data for
microwave networks can be used to predict some configurations quite accurately and
therefore presents an opportunity to automate parts of the configuration process for
microwave links. However, the evaluation of our recommendations is challenging as
the application of our recommendations is risky and might harm the networks in an
early stage
Effect of the reversal of coenzyme specificity by expression of mutated Pichia stipitis xylitol dehydrogenase in recombinant Saccharomyces cerevisiae
Xylose-metabolizing Saccharomyces cerevisiae strains overexpressing the TKL1 and TAL1 genes encoding the pentose phosphate pathway enzymes transketolase and transaldolase.
Saccharomyces cerevisiae was metabolically engineered for xylose utilization. The Pichia stipitis CBS 6054 genes XYL1 and XYL2 encoding xylose reductase and xylitol dehydrogenase were cloned into S. cerevisiae. The gene products catalyze the two initial steps in xylose utilization which S. cerevisiae lacks. In order to increase the flux through the pentose phosphate pathway, the S. cerevisiae TKL1 and TAL1 genes encoding transketolase and transaldolase were overexpressed. A XYL1- and XYL2-containing S. cerevisiae strain overexpressing TAL1 (S104-TAL) showed considerably enhanced growth on xylose compared with a strain containing only XYL1 and XYL2. Overexpression of only TKL1 did not influence growth. The results indicate that the transaldolase level in S. cerevisiae is insufficient for the efficient utilization of pentose phosphate pathway metabolites. Mixtures of xylose and glucose were simultaneously consumed with the recombinant strain S104-TAL. The rate of xylose consumption was higher in the presence of glucose. Xylose was used for growth and xylitol formation, but not for ethanol production. Decreased oxygenation resulted in impaired growth and increased xylitol formation. Fermentation with strain S103-TAL, having a xylose reductase/xylitol dehydrogenase ratio of 0.5:30 compared with 4.2:5.8 for S104-TAL, did not prevent xylitol formation
Xylose utilization and production of xylitol by recombinant <i>Saccharomyces cerevisiae</i>
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