Heterologous expression and characterization of an N-acetyl-β-D-hexosaminidase from Lactococcus lactis ssp. lactis IL1403     

Nguyen HA  Nguyen TH  Křen V  Eijsink VG  Haltrich D  Peterbauer CK 《Journal of agricultural and food chemistry》2012,60(12):3275-3281

The lnbA gene of Lactococcus lactis ssp. lactis IL1403 encodes a polypeptide with similarity to lacto-N-biosidases and N-acetyl-β-D-hexosaminidases. The gene was cloned into the expression vector pET-21d and overexpressed in Escherichia coli BL21* (DE3). The recombinant purified enzyme (LnbA) was a monomer with a molecular weight of approximately 37 kDa. Studies with chromogenic substrates including p-nitrophenyl N-acetyl-β-D-glucosamine (pNP-GlcNAc) and p-nitrophenyl N-acetyl-β-D-galactosamine (pNP-GalNAc) showed that the enzyme had both N-acetyl-β-D-glucosaminidase and N-acetyl-β-D-galactosaminidase activity, thus indicating that the enzyme is an N-acetyl-β-D-hexosaminidase. K(m) and k(cat) for pNP-GlcNAc were 2.56 mM and 26.7 s(-1), respectively, whereas kinetic parameters for pNP-GalNAc could not be determined due to the K(m) being very high (>10 mM). The optimal temperature and pH of the enzyme were 37 °C and 5.5, respectively, for both substrates. The half-life of activity at 37 °C and pH 6.0 was 53 h, but activity was completely abolished after 30 min at 50 °C, meaning that the enzyme has relatively low temperature stability. The enzyme was stable in the pH 5.5-8 range and was unstable at pH below 5.5. Studies with natural substrates showed hydrolytic activity on chito-oligosaccharides but not on colloidal chitin or chitosan. Transglycosylation products were not detected. In all, the data suggest that LnbA's role may be to degrade chito-oligosaccharides that are produced by the previously described chitinolytic system of L. lactis.  相似文献   

Regional Contamination of Moravia (South-Eastern Czech Republic): Temporal Shift of Pb and Zn Loading in Fluvial Sediments     

Matys Grygar  Tomáš  Sedláček  Jan  Bábek  Ondřej  Nováková  Tereza  Strnad  Ladislav  Mihaljevič  Martin 《Water, air, and soil pollution》2012,223(2):739-753

Regional contamination by Pb and Zn in southern Moravia (south-east part of the Czech Republic) in the twentieth century was analysed in Brno Dam lake sediments and in floodplain sediments of the Morava River near Strážnice. The age model for the Brno Dam lake sediments has been obtained by ¹³⁷Cs (maxima corresponding to the nuclear tests in atmosphere and the 1986 Chernobyl accident) and the construction of the dam (1940); the time constraints for the Morava River sediments was the erection of flood defences (1930s) and ²¹⁰Pb dating. In the case of floodplain sediments, profiles exhibiting post-depositional mobilisation of heavy metals by pedogenic processes (gleying) must be excluded to reconstruct the history of contamination. There was a relatively fast joint onset of Pb and Zn load since the early stages of industrialisation in the first half of the twentieth century, but then the concentrations of these two metals developed in a different manner. Pb load only slightly increased till its peak in 1960s and 1970s. The increase of Zn load was rather stepwise: Soon before 1930s (Morava River floodplain) and in 1940s and 1950s (in Brno Lake), the relative contamination by Zn was much lower than during its peak in the 1970s to the present days. The offset of Pb and Zn contamination curves could have been caused by three different artificial sources of these heavy metals. The temporal shift of Pb and Zn loads can be used for dating sediments.  相似文献   

The importance of the gravel excavation industry for the conservation of grassland butterflies     

Magdalena Lenda  Piotr Skórka  Dawid Moroń  Zuzanna M. Rosin  Piotr Tryjanowski 《Biological conservation》2012,148(1):180-190

Conservation biology often relies on the protection of (semi)natural habitat remnants. However, the ever increasing human population is taking over natural resources and habitats. Here, contrary to most other studies, we ask how human-associated severe changes in the environment can be used to enrich local biodiversity. We tested if industrial activity (gravel excavation) leads to the creation of habitats that support grassland butterflies and how these areas add to the richness of local species when compared to typical semi-natural habitats (grasslands). We also identified key factors affecting the richness, abundance, diversity and commonness of butterfly species to provide practical recommendations. Species richness, diversity index and the occurrence of rare species were higher in gravel-pit shores than in grasslands. The richness of butterfly species and their abundance were positively affected by the richness of plant species, shrub density and age of the gravel-pit but negatively by the cover of water reservoirs in the surrounding area and the isolation of gravel-pits from grasslands. Butterfly diversity was positively influenced by the richness of plant species and proximity of human settlement but negatively by area of the shore and isolation. Our study is the first one to show the high value of gravel-pits for the conservation of butterflies. We recommend the inclusion of gravel-pits in a system of ecological networks and management of their surroundings to improve the colonization rate of rare species. We suggests that directing interest to the possible positive effects of industrial development on biodiversity may support conservation efforts.  相似文献   

Finite element method model of the mechanical behaviour of Jatropha curcas L. seed under compression loading     

Michal Petrů  Ondřej Novák  David Herák  Satya Simanjuntak 《Biosystems Engineering》2012,111(4):412-421

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Investigation on acoustic behavior and air permeability of struto nonwovens     

Tao Yang  Xiaoman Xiong  Rajesh Mishra  Jan Novák  Jiří Chaloupek  Filip Sanetrnik  Jiří Militký 《Fibers and Polymers》2016,17(12):2078-2084

This work deals with the study of acoustic performance of struto nonwovens and their relation to fabric air permeability. In order to achieve the objective of the research, sound absorption coefficient of struto nonwovens was determined via impedance tube method, the average value of sound absorption coefficient (α?) was calculated. Air permeability of struto nonwovens was examined by using FX3300 Textech Air Permeability Tester. Results showed that struto nonwoven exhibited good absorption ability at frequency bands 3000-6400 Hz while it was ineffective for frequency lower than 3000 Hz. Struto nonwovens with high GSM and fabric thickness showed better acoustic performance and lower air permeability. It was observed that α? was inversely proportional to air permeability, with correlation coefficient 0.95. It was concluded that air permeability can be used as a criterion of sound absorption behavior of struto nonwovens. A lower air permeability suggests a better sound absorption performance for struto nonwoven fabrics.  相似文献   

Ethnobotanical knowledge and agrobiodiversity in subsistence farming: case study of home gardens in Phong My commune, central Vietnam     

Martina Vlkova  Zbynek Polesny  Vladimir Verner  Jan Banout  Marek Dvorak  Jaroslav Havlik  Bohdan Lojka  Petr Ehl  Jitka Krausova 《Genetic Resources and Crop Evolution》2011,58(5):629-644

Ethnobotanical survey was conducted in 101 randomly selected home gardens of Phong My commune, central Vietnam, situated in the buffer-zone of Natural Reserve. Data were collected through semi-structured questionnaires and direct observation. Sixty-seven species belonging to 35 families were identified to be used for various purposes. For each species the botanical and vernacular names, plant parts used and main purposes of use are given. The major use categories reported for plant species were food (86%), medicine (32%) and firewood (32%), however, seventy-seven percent of all inventoried plants have multiple uses. The species Artocarpus heterophyllus Lam., Citrus grandis Osbeck, Citrus reticulata Blanco, Ipomoea batatas (L.) Lam. and Musa spp. were identified as the main sources of plant foods consumed within the households. Statistical analyses indicated by Shannon-Wiener and Margalef indices have shown that local species diversity and richness is affected by home garden size. On the contrary, no relationship between diversity and home garden age was found. On the basis of a cluster analysis of plant species diversity, five home garden types were differentiated. In comparison to previously reported studies on tropical home gardens, the diversity in Phong My is lower, probably due to market-oriented strategy. Nevertheless, based on the results achieved, we can conclude that useful plants cultivated in local home gardens provide valuable foods complementing daily diet and subsequently contributing to socioeconomic status of the households.  相似文献   

Manure application followed by biochar application increases plant production regardless of soil dehydrogenase activity     

H. Dvořáčková  J. Dvořáček 《Soil Use and Management》2023,39(4):1557-1569

Biochar is obtained by the pyrolysis of biomass, and contains abundant carbon and minerals. Biochar supplementation of soils can greatly improve soil health and quality, but these beneficial effects typically develop slowly over time. Depending on the quality of the biochar and the soil to which it is applied, it may take years before positive effects are apparent. This is because organic substances are slowly sorbed onto the biochar over time, and the biochar eventually becomes part of the sorption complex of the soil. It is therefore advisable to apply biochar together with some organic material. We examined the effect of co-application of different doses of biochar with manure on soil dehydrogenase activity (DHA), soil oxidizable carbon (COX), cumulative soil respiration, soil buffering capacity, the soil exchange reaction (pH/KCl) and the production yield of winter rape seeds. We also determined seed production when artificial granular fertilizers were added to biochar and manure. The results showed that the application of biochar and manure significantly increased grain yield, DHA, the soil exchange reaction and cumulative respiration. Thus, application of biochar with organic material can increase seed yield and some properties of agricultural soils. However, the positive effect of biochar on seed yield was not directly proportional to biochar dose, in that the seed yield was lower for a biochar dose of 45 t/ha than 30 t/ha.  相似文献   

Influence of some fertilizer chemical properties on magnesium resorption from leaf surface of oats     

Petr Cígler  Martin Hrubý  Stanislav Kuzel 《Journal of plant nutrition》2013,36(8):1241-1251

Eight organic and either inorganic magnesium (Mg) compounds (sulphate, acetate, caproate, laurate, glycine salt, L‐valine salt, L‐phenylalanine salt, and ethylene‐diaminetetraacetic acid magnesium disodium salt) were tested for Mg resorption from the leaf surface of oats (Avena sativa L. cv. Zlat'ák) and for biological availability. The plants were grown on Mg‐deficient Hoagland nutrient solution. Significant differences among the alternatives studied were found through one‐way ANOVA in all parameters of plants (top and root dry weight, Mg content in tops and roots, chlorophyll a and b content and top height). A very significant decrease of Mg content in plants and aggravation of the plant health status with increasing molar weight value (Mr) of anhydrous compound used in corresponding experimental alternative was observed. The best results were obtained in the case of magnesium sulphate (MgSO₄.7H₂O) (the lowest Mr value) while the worst were observed in the case of Mg laurate. A different diameter of the biggest particle necessary to be absorbed with Mg (Mg complex molecule/anion, salt anion) resulting in different mobility of this particle in water solution was proposed to be the main reason of this effect. This diameter is closely related to the Mr value of the particular compound in this case. Surprisingly, no effect of fertilizer polarity on Mg penetration was observed. The effect of complex stability of some Mg compounds on Mg penetration was also investigated. The biological availability significantly decreased with the increase of the complex strength.  相似文献   

Fate of humic acids isolated from natural humic substances     

Lubica Pospíšilová  Markéta Komínková  Ondřej Zítka  René Kizek  Gabriela Barančíková  Tadeáš Litavec 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(6):517-528

Composition of humic acids (HA) is a function of plant-derived inputs, degradation processes regulated by microorganisms, organo-mineral interactions and age. Characterization of different origin humic substances is important for evaluation of their contribution to stabile and labile carbon pool in the environment. The relative abundance of chemical components in HA isolated from soils, compost, commercial lignohumates, alginite, acadiane and lignite was studied with aim to quantify content of important biomarkers such as amino acid, lipids and polyphenols. HA were considered as a heterogeneous complex and high concentration of peptides, polyphenols and lipids was determined in acadian-HA to compare with soil-HA. Compost-HA contained much more amino acids to compare with soil-HA samples. Alginite-HA and lignite-HA were similar in biomarkers content to soil-HA. Fourier transform infrared spectroscopy confirmed that chemical composition and functional groups content differs with the origin, humification degree and the age of studied samples. Soil-HA are typically composed of a variety of ?OH, COOH?, C–O, C–H₂, (aliphatic and aromatic) groups, quinines, lignin fragments, polysaccharide, monosaccharide and proteins fragments, which are linked together by ?O?, ?NH?, ?H=, >C=O, metal ions and –S? groups. ¹³C NMR spectroscopy showed that aromatic carbon content was the highest in lignite-HA and soil-HA.  相似文献   

Understanding pathogen population structure and virulence variation for efficient resistance breeding to control cucurbit powdery mildews     

Aleš Lebeda  Božena Sedláková  Eva Křístková  Mark P. Widrlechner  Evsey Kosman 《Plant pathology》2021,70(6):1364-1377

Cucurbit powdery mildew (CPM) is caused most frequently by well-differentiated obligate erysiphaceous ectoparasites Golovinomyces orontii and Podosphaera xanthii, which vary in their ecology and virulence. All economically important cucurbit crops host both of these CPM species. Breeding of cucurbits for CPM resistance is highly important worldwide, but adequate knowledge of CPM species determination, as well as virulence structure, population dynamics, and spatiotemporal variation of these pathogens, has not yet been achieved. New tools have been developed to enhance research on CPM virulence variation for more efficient breeding and seed and crop production. A set of differential genotypes of Cucumis melo, with high differentiation capacity, may contribute substantially to understanding of variation in CPM virulence at both individual and population levels. Long-term observations (2001–2012) of CPM pathogens in the Czech Republic were used to analyse virulence variation within and among annual CPM populations and demonstrate the utility of recently developed tools for studying species variability and virulence variation of CPM pathogens worldwide. Detailed analyses of diversity and spatiotemporal fluctuations in the composition of CPM populations provide crucial information for shaping breeding programmes and predicting the most effective sources of race-specific resistance. The primary aim of this work was to create a uniform framework for determination of CPM species structure and diversity, virulence phenotypes, virulence and phenotype frequencies, phenotype complexity, dynamics, and variation within and among CPM populations. In addition, practical advice is presented on how to select the most relevant data and interpret them for use in cucurbit resistance breeding.  相似文献