54 research outputs found
Continuous production of xylooligosaccharides in a packed bed reactor with immobilized–stabilized biocatalysts of xylanase from Aspergillus versicolor
Predicting the Impact of Climate Change on Threatened Species in UK Waters
Global climate change is affecting the distribution of marine species and is thought to represent a threat to biodiversity. Previous studies project expansion of species range for some species and local extinction elsewhere under climate change. Such range shifts raise concern for species whose long-term persistence is already threatened by other human disturbances such as fishing. However, few studies have attempted to assess the effects of future climate change on threatened vertebrate marine species using a multi-model approach. There has also been a recent surge of interest in climate change impacts on protected areas. This study applies three species distribution models and two sets of climate model projections to explore the potential impacts of climate change on marine species by 2050. A set of species in the North Sea, including seven threatened and ten major commercial species were used as a case study. Changes in habitat suitability in selected candidate protected areas around the UK under future climatic scenarios were assessed for these species. Moreover, change in the degree of overlap between commercial and threatened species ranges was calculated as a proxy of the potential threat posed by overfishing through bycatch. The ensemble projections suggest northward shifts in species at an average rate of 27 km per decade, resulting in small average changes in range overlap between threatened and commercially exploited species. Furthermore, the adverse consequences of climate change on the habitat suitability of protected areas were projected to be small. Although the models show large variation in the predicted consequences of climate change, the multi-model approach helps identify the potential risk of increased exposure to human stressors of critically endangered species such as common skate (Dipturus batis) and angelshark (Squatina squatina)
Think globally, measure locally: The MIREN standardized protocol for monitoring plant species distributions along elevation gradients
Climate change and other global change drivers threaten plant diversity in mountains worldwide. A widely documented response to such environmental modifications is for plant species to change their elevational ranges. Range shifts are often idiosyncratic and difficult to generalize, partly due to variation in sampling methods. There is thus a need for a standardized monitoring strategy that can be applied across mountain regions to assess distribution changes and community turnover of native and non-native plant species over space and time. Here, we present a conceptually intuitive and standardized protocol developed by the Mountain Invasion Research Network (MIREN) to systematically quantify global patterns of native and non-native species distributions along elevation gradients and shifts arising from interactive effects of climate change and human disturbance. Usually repeated every five years, surveys consist of 20 sample sites located at equal elevation increments along three replicate roads per sampling region. At each site, three plots extend from the side of a mountain road into surrounding natural vegetation. The protocol has been successfully used in 18 regions worldwide from 2007 to present. Analyses of one point in time already generated some salient results, and revealed region-specific elevational patterns of native plant species richness, but a globally consistent elevational decline in non-native species richness. Non-native plants were also more abundant directly adjacent to road edges, suggesting that disturbed roadsides serve as a vector for invasions into mountains. From the upcoming analyses of time series, even more exciting results can be expected, especially about range shifts. Implementing the protocol in more mountain regions globally would help to generate a more complete picture of how global change alters species distributions. This would inform conservation policy in mountain ecosystems, where some conservation policies remain poorly implemented
Modulation of the regioselectivity of Thermomyces lanuginosus lipase via biocatalyst engineering for the Ethanolysis of oil in fully anhydrous medium
Novel support for enzyme immobilization prepared by chemical activation with cysteine and glutaraldehyde
Immobilization of enzymes on glutaraldehyde-activated supports has been largely used on supports previously activated with amine groups. Therefore, the supports are positively charged hence usually the immobilization is promoted through a two step mechanism: in a first step the enzyme is adsorbed on the support via an anionic exchange mechanism and then, the covalent immobilization occurs. In this paper a new glutaraldehyde activated support without a net charge is presented and characterized in immobilizations of trypsin, penicillin acylase G, lipase and E. coli BL21 cell extract. Immobilization mechanism was studied and this was produced without an adsorption step. This support promoted initially a reversible immobilization, converting into irreversible after incubation of the enzyme-support for several days or after a reduction step. In addition the stability of glutaraldehyde groups was studied retaining around 50 and 25% of its immobilization capacity for 24 h at pH 7 and 10 respectively. This fact allows the incubation of the enzyme with the support even at alkaline pH promoting an extra stabilization factor for trypsin on this support
Regioselective hydrolysis of different peracetylated beta -monosaccharides by immobilized lipases from different sources. Key role of the immobilization
The effect of the immobilization strategy
on the activity, specificity and regioselectivity of
three different lipases [those from Thermomyces lanuginose
(TLL), Aspergillus niger (ANL) and Candida
antarctica B (CAL-B)] in the hydrolysis of peracetylated
b-monosaccharides has been evaluated.
Three very different immobilization strategies were
utilized, covalent attachment, anionic exchange and
interfacial activation on a hydrophobic support. The
octyl-TLL immobilized preparation was the most efficient
biocatalyst in the hydrolysis of 1,2,3,4,6-penta-
O-acetyl-beta-D-galactopyranose, producing specifically
6-hydroxy-1,2,3,4-tetra-O-acetyl-beta-D-galactopyranose
in 95% overall yield, whereas the CNBr-TLL preparation
was 48 times slower and regioselective towards
the anomeric position, producing the 1-hydroxy
derivative in 70% yield. The PEI-TLL immobilized
preparation was the most efficient catalyzing
the hydrolysis of 1,2,3,4,6-penta-O-acetyl-beta-D-glucopyranose,
permitting us to obtain up to 70% of the
6-hydroxy product. In the hydrolysis of 2-acetamido-
2-deoxy-1,3,4,6-tetra-O-acetyl-beta-D-glucopyranose, the
octyl-CALB preparation was not selective at all for
the production of monohydroxy products whereas
when CAL-B was immobilized on PEI-agarose, the
enzyme was highly specific and regioselective producing
the 6-hydroxy-2-acetamido-2-deoxy-1,3,4-tri-
O-acetyl-beta-D-glucopyranose in 70% yield
Improving the Activity of Lipases from Thermophilic Organisms at Mesophilic Temperatures for Biotechnology Applications
Use of aqueous two-phase systems for in situ extraction of water soluble antibiotics during their synthesis by enzymes immobilized on porous supports
Use of dextrans as long and hydrophilic spacer arms to improve the performance of immobilized proteins acting on macromolecules
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