The utilization of gene technology and of new production technologies have made industrial enzymes with improved properties or better cost performance available. This has in turn opened important new areas of enzyme applications. The benefits to the customers are considerable: cost savings in the application process, improved product quality, and in most cases also a significantly reduced impact on the environment.
Gene technology offers several benefits to the enzyme industry. This technology enables the use of safe, well-documented host organisms easy to cultivate, the microbial production of enzymes of animal and plant origin, the realization of enhanced efficiency and high product purity, and also the production of enzymes with improved stability and activity.
Developments in production technology include advanced control methods, the use of expert systems, and the application of large-scale crystallization.
As case stories the development of a lipase and of a cellulase is described. The effect on environment of enzyme application and production is discussed. 相似文献
Leptodora kindti is a very efficient invertebrate predator. Its searching mode of preying is tactile. The setae of the first thoracic limb act as mechanoreceptors, the other thoracic limbs, thorax and head together form the shape of an open basket in which after encounter the prey is pushed in by the aid of the first thoracic limbs and the furca. In Neusiedler See, small individuals of Diaphanosoma brachyurum (0.6–0.9 mm) are the preferred prey, rarely copepods are taken. The predation rate is influenced by temperature, prey density and predator size and varies between less than one and 12 prey items per predator per day. At high predator densities, Leptodora will have a substantial effect on the Diaphanosoma population of Neusiedler See. 相似文献
This study focuses on the effect of fire on lowland heathlands at the extreme southern edge of their European distribution
(Vauda Nature Reserve, NW Italy). Forty-nine plots (50 m radius) were surveyed between 1999 and 2006. Each year, fire occurrences
were recorded and per cent cover of four vegetation types (grassland, heath, low shrubland, and tall shrubland) was estimated
in each plot. Vascular plant species richness was also recorded in 255, 1 m2 quadrats. After a fire, grassland vegetation expanded, but then declined rapidly as heath and shrubland recovered: 7 years
after a fire, tall shrubland encroached on to more than 40% of the plots, and grassland declined from 50% to 20% cover. Between
1999 and 2006, Betula pendula shrubland greatly expanded, while grassland decreased over most of the Reserve, even where fire frequency was high. Tall
shrubland had low plant diversity and was dominated by widespread species of lower conservation value. By contrast, early
successional vegetation (grassland and low shrubland) had higher richness and more narrowly distributed species, indication
that the development of tall shrubland causes significant species loss in the heathland. Italian lowland heathlands are characterized
by high rates of shrubland encroachment that threatens both habitat and species diversity. Burning frequencies of once in
3–6 years seem appropriate in this habitat, but burning alone might not suffice without actions to increase herbivore grazing. 相似文献
We developed a simplified emission dispersion and exposure-assessment model designed to reflect the site-specific health impacts
of air pollution in life-cycle impact assessment (LCIA). We proposed an EXposure Per Emission Coefficient (EXPEC), a dimensionless
parameter representing the relative amount of pollutant inhaled per emission. EXPEC values were calculated for two typical
source categories - electric power plants and road vehicles — on a concentric circle model. The EXPEC values were significantly
different for different locations and source categories. We examined the application of EXPEC in a case study that compared
the effects of emissions from electric and gasoline-engine vehicles. EXPEC is a useful tool for assessing spatially differentiated
potential impacts. 相似文献
The Seine River estuary (France) is the receptacle of a drainage basin characterised by high population density, heavy industrial
activity and intensive agriculture. Whereas nitrate concentrations are high due to diffuse sources in the upstream drainage
basin, ammonium mainly originates from the effluents of the Achères wastewater treatment plant (WWTP) downstream from Paris
and its suburbs (6.5 million equivalent-inhabitants). Ammonium is mostly nitrified in the tidal freshwater estuary and nitrification
causes a strong summer oxygen deficit. Average longitudinal summer profiles of oxygen and nitrogen concentrations for two
periods, between 1993–1997 and 1998–2003 in dry hydrological conditions (excluding the wet years 2000 and 2001) clearly reflect
the changes due to the improved treatment of wastewater from Paris and its suburbs. On the basis of daily water flux data
and twice monthly nitrogen measurements at the boundaries of the upstream freshwater estuarine section (108 km), we calculated
nitrification and denitrification fluxes, whose annual averages were 43 and 71 × 103 kg N d−1 respectively from 1993 to 2003, with summer values (July–September) representing 73 and 57% of the annual fluxes, respectively.
The degree of denitrification in the upper estuary appears to be closely related to the nitrification, itself more loosely
related to the amount of reduced nitrogen (Kjeldahl) brought by the treated effluents from the Achères WWTP. We estimated
the total N2O emissions to about 40 kg N d−1 (25–60 kg N d−1) in the same sector. 相似文献