Production of Galacto-oligosaccharides by the β-Galactosidase from Kluyveromyces lactis : comparative analysis of permeabilized cells versus soluble enzyme     

Rodriguez-Colinas B  de Abreu MA  Fernandez-Arrojo L  de Beer R  Poveda A  Jimenez-Barbero J  Haltrich D  Ballesteros Olmo AO  Fernandez-Lobato M  Plou FJ 《Journal of agricultural and food chemistry》2011,59(19):10477-10484

The transgalactosylation activity of Kluyveromyces lactis cells was studied in detail. Cells were permeabilized with ethanol and further lyophilized to facilitate the transit of substrates and products. The resulting biocatalyst was assayed for the synthesis of galacto-oligosaccharides (GOS) and compared with two soluble β-galactosidases from K. lactis (Lactozym 3000 L HP G and Maxilact LGX 5000). Using 400 g/L lactose, the maximum GOS yield, measured by HPAEC-PAD analysis, was 177 g/L (44% w/w of total carbohydrates). The major products synthesized were the disaccharides 6-galactobiose [Gal-β(1→6)-Gal] and allolactose [Gal-β(1→6)-Glc], as well as the trisaccharide 6-galactosyl-lactose [Gal-β(1→6)-Gal-β(1→4)-Glc], which was characterized by MS and 2D NMR. Structural characterization of another synthesized disaccharide, Gal-β(1→3)-Glc, was carried out. GOS yield obtained with soluble β-galactosidases was slightly lower (160 g/L for Lactozym 3000 L HP G and 154 g/L for Maxilact LGX 5000); however, the typical profile with a maximum GOS concentration followed by partial hydrolysis of the newly formed oligosaccharides was not observed with the soluble enzymes. Results were correlated with the higher stability of β-galactosidase when permeabilized whole cells were used.  相似文献   

The Content of Phenolic Compounds and Radical Scavenging Activity Varies with Carrot Origin and Root Color     

Maria Leja  Iwona Kamińska  Maike Kramer  Anna Maksylewicz-Kaul  Dietmar Kammerer  Reinhold Carle  Rafal Baranski 《Plant foods for human nutrition (Dordrecht, Netherlands)》2013,68(2):163-170

The contents of phenolic compounds and radical scavenging activities were assessed in a carrot collection comprising 35 cultivars, landraces and breeding populations. The accessions originated from various world regions and they represented Eastern and Western carrot gene pools. In two-year field trial carrot roots of orange, red, yellow, white and purple color were cultivated, freeze-dried and analyzed for phenolic content by Folin-Ciocalteu assay and UV/Vis assay. Radical scavenging activity in the extracts was determined with a stable DPPH radical. Carrots developing purple roots possessed on average 9 times more phenolics than roots of other colors. Furthermore, they were rich in anthocyanins that caused very high antiradical activity. Red carrots showed higher antioxidant activity than orange, yellow and white carrots and in the season of lower rainfall they accumulated higher amounts of phenolic compounds. Carrots of Asian origin belonging to Eastern gene pool were more often purple or red and richer in phenolics and had higher antiradical activity than those from the Western gene pool with mainly orange roots.  相似文献   

First report on Parafilaria bovicola (Nematoda: Filaroidea) in Germany     

Dietmar Hamel  Holger Axt 《Research in veterinary science》2010,89(2):209-91

From September 2008 to April 2009 several cases of spontaneous bleeding and nodules from the back and withers area of cattle otherwise considered as healthy have been reported from several farms in south-western and southern Germany. Successive investigation of these cases gave strong evidence of Parafilaria (P.) bovicola infections due to their seasonal occurrence and specific pathological lesions. There was no history of animal import from endemic countries for the affected cattle herds. In one case, a nodule containing nematode fragments and an intact female nematode were recovered from a slaughtered White Galloway bull. This sample was identified as P. bovicola and is the first report of bovine parafilariosis in Germany.  相似文献   

Seroprevalence and bacteremia [corrected] of Anaplasma phagocytophilum in cats from Bavaria and Lower Saxony (Germany)     

Hamel D  Bondarenko A  Silaghi C  Nolte I  Pfister K 《Berliner und Münchener tier?rztliche Wochenschrift》2012,125(3-4):163-167

Anaplasma (A.) phagocytophilum is a tick-transmitted obligate intracellular bacterium and has been identified in a wide range of mammalian species, causing febrile disease in some. Few reports show that it can also cause granulocytic anaplasmosis in cats. As data on the occurrence of A. phagocytophilum in cats from Germany is limited, a total of 326 serum and 306 EDTA-blood samples from cats from Germany were screened by direct (Giemsa-stained blood/buffy coat smears, real-time PCR) and indirect (IFAT) methods. Of 274 Giemsa-stained blood smears which could be evaluated none was positive for morulae, but one blood sample (< or =0.1%; 1/306) was positive for A. < or = phagocytophilum-DNA in PCR. Antibodies (cutoff > or = 1:64) were detected in 53 out of 326 samples (16.2%). Altogether, the results show a high seroprevalence rate of anti-A. phagocytophilum antibodies in cats in Germany while the low detection rate of this bacterial agent by direct methods is similar to those of other studies on A. phagocytophilum infections in cats.  相似文献   

Landscape patch shape complexity as an effective measure for plant species richness in rural landscapes   总被引：13，自引：0，他引：13  

Moser  Dietmar  Zechmeister  Harald G.  Plutzar  Christoph  Sauberer  Norbert  Wrbka  Thomas  Grabherr  Georg 《Landscape Ecology》2002,17(7):657-669

The application of landscape patch shape complexity as a predictor ofvascularplant and bryophyte species richness is analysed. Several common complexityindices (shape index, fractal dimension, comparison to the area of the minimumbounding rectangle) are tested for their predictive power for plant speciesrichness. One new robust measure for shape complexity is presented whichovercomes some disadvantages of common complexity measures applied to highresolution analysis of agricultural landscapes based on aerial photographs. Thenew index is based on the number of shape characterising points along apolygons boundary. This new measure shows promising predictive capabilitiesforspecies richness of vascular plants and bryophytes (correlation coefficient:0.85 for vascular plants, 0.74 for bryophytes).This revised version was published online in May 2005 with corrections to the Cover Date.  相似文献   

Evaluating the accuracy and generality of a hybrid patch model   总被引：3，自引：0，他引：3  

Seidl R  Lexer MJ  Jäger D  Hönninger K 《Tree physiology》2005,25(7):939-951

Forest patch models have been used extensively to simulate vegetation development under current and changing environmental conditions. However, their physiological foundation is subject to criticism and recent validation experiments against long-term growth and yield data have shown major deficiencies in reproducing observed growth patterns of mixed-species forests. Here we describe the modified forest patch model PICUS Version 1.3, a model variant that couples the structurally detailed three-dimensional patch model PICUS Version 1.2 and the physiologically based stand-level production module of the 3-PG (Physiological Principles in Predicting Growth) model. The approach attempts to combine the ability of PICUS v1.2 to simulate forest dynamics on time scales relevant to forest succession with a simplified but successful production model based on the concept of radiation-use efficiency. We evaluated the hybrid model in a series of simulation experiments. Results indicated a realistic response to a climate sensitivity experiment: the response to environmental gradients was well captured both in terms of productivity on time scales of a rotation length and of forest succession over several hundreds of years. Testing against independent long- term growth and yield data revealed good correspondence between observed and predicted values of volume production and stand structure. Further model development should include a dynamic soil component to consider effects of nutrient cycling.  相似文献   

Elimination of heavy metals from process waters of the bioleaching process by electrolysis     

Roland?FischerEmail author  Heinz?Seidel  Dietmar?Rahner  Peter?Morgenstern  Christian?L?ser 《Journal of Soils and Sediments》2002,2(4):166-168

2 Conclusions  The investigations into the membrane electrolysis cell show that electrochemical metal separation from bioleaching process waters can represent a practical alternative for metal separation by alcalization, Coal and platinized titanium material exhibit good anodic resistance at the current densities tested. By contrast, high-grade steel and to some extent lead anodes were dissolved and are hence unsuitable for this purpose. However, for practical application, suitable ways are required to discharge the precipitates containing heavy metals deposited on the electrodes from the electrolysis cell and to prevent membrane clogging. Regarding the main components zinc, manganese, and nickel, the combination electrodes proved to be suitable for eliminating the heavy metals from the aqueous phase. Another way of treating diluted process waters containing sulphuric acidic and heavy metals is to concentrate the sulphuric acid in the anode region and to precipitate the heavy metals in the cathode region. The sulphuric acid recovered could then be returned to the leaching process, hence avoiding wastewater.  相似文献   

Homodimeric β-galactosidase from Lactobacillus delbrueckii subsp. bulgaricus DSM 20081: expression in Lactobacillus plantarum and biochemical characterization     

Nguyen TT  Nguyen HA  Arreola SL  Mlynek G  Djinović-Carugo K  Mathiesen G  Nguyen TH  Haltrich D 《Journal of agricultural and food chemistry》2012,60(7):1713-1721

The lacZ gene from Lactobacillus delbrueckii subsp. bulgaricus DSM 20081, encoding a β-galactosidase of the glycoside hydrolase family GH2, was cloned into different inducible lactobacillal expression vectors for overexpression in the host strain Lactobacillus plantarum WCFS1. High expression levels were obtained in laboratory cultivations with yields of approximately 53000 U of β-galactosidase activity per liter of medium, which corresponds to ~170 mg of recombinant protein per liter and β-galactosidase levels amounting to 63% of the total intracellular protein of the host organism. The wild-type (nontagged) and histidine-tagged recombinant enzymes were purified to electrophoretic homogeneity and further characterized. β-Galactosidase from L. bulgaricus was used for lactose conversion and showed very high transgalactosylation activity. The maximum yield of galacto-oligosaccharides (GalOS) was approximately 50% when using an initial concentration of 600 mM lactose, indicating that the enzyme can be of interest for the production of GalOS.  相似文献   

Regionalization of Magnetic Susceptibility Measurements Based on a Multiple Regression Approach     

Christine Fürst  Dietmar Zirlewagen  Carsten Lorz 《Water, air, and soil pollution》2010,208(1-4):129-151

The article presents results of a case study in northeastern Germany, where magnetic susceptibility assessment was carried out at grid-wise field measurements. The measurements were clustered into three different depth levels, which represent the humus layer, the transition zone between humus layer and mineral horizon, and the mineral horizon. Taking these three depth levels, a multiple regression-based regionalization approach was applied, testing and using additional environmental parameters derived from geology, topography, and stand type with the aim to develop a comprehensive model for spatial variability of magnetic susceptibility. Spatial variation of magnetic susceptibility was predicted with a high precision by the multiple linear regression models. A slightly differing set of model parameters was selected for the single depth levels. In tendency, magnetic susceptibility values in depth level 6–10 cm were best explained by the distance to Bitterfeld and by soil properties. In depth level 11–15 cm, variables which describe the orographic conditions and stand properties gain in importance. In depth level 21–25 cm, variables indicating soil and site properties disappear completely. Here, aspect and land surface characteristics play a major role together with stand properties. A spatial stratification of the model for a distance of up to 25 km to the former emitters provided a further improvement of the model quality considering the prediction of small-scale variations of magnetic susceptibility.  相似文献   

Comparison between discontinuous and continuous lactose conversion processes for the production of prebiotic galacto-oligosaccharides using beta-galactosidase from Lactobacillus reuteri     

Splechtna B  Nguyen TH  Haltrich D 《Journal of agricultural and food chemistry》2007,55(16):6772-6777

Galacto-oligosaccharide (GOS) formation from lactose in discontinuous and continuous modes of conversion was investigated using beta-galactosidase (beta-gal) from Lactobacillus reuteri. A continuous stirred tank reactor (CSTR) with an external crossflow membrane was set up, and continuous GOS production was analyzed and compared to the batchwise formed GOS product. Marked differences were detected for the two reactor setups. Above 65% lactose conversion, the GOS yield was lower for the CSTR due to a lower content of tri- and tetrasaccharides in the reaction mixture. In the CSTR, beta-gal from L. reuteri showed up to 2-fold higher specificity toward the formation of beta-(1-->6)-linked GOS, with beta-D-Galp-(1-->6)-D-Glc and beta-D-Galp-(1-->6)-D-Gal being the main GOS components formed under these conditions. This could be used to synthesize more defined GOS products.  相似文献