216 research outputs found

    Compost Process and Organic Fertilizers Application in China

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    Composting is an inexpensive and sustainable treatment for solid wastes. The composting industry has been growing rapidly because of a boom in the animal industry in China over the past decades. In this chapter, we introduce composting process and status in China, especially in Jiangsu Province. Meanwhile, the developed novel spectroscopy techniques are also introduced, which are more suitable for assessment of compost maturity than the conventional techniques in view of ease of sample preparation, rapid spectrum acquisition, and nondestructive nature of the analysis. These novel spectroscopy techniques include near-infrared reflectance spectroscopy (NIRS)––partial least squares (PLS) analysis and fluorescence excitation–emission matrix (EEM) spectroscopy––parallel factor (PARAFAC) analysis. In addition, organic fertilizer amendments can not only improve soil fertility but also offset chemical fertilizers’ nanoscale changes. Emerging cutting-edge technologies of synchrotron-based X-ray absorption fine structure (XAFS) spectroscopy and nanoscale secondary ion mass spectrometry (NanoSIMS) were used to identify the composition of organic carbon and minerals and their correlations, respectively. Recently, investigators have shown that organic fertilizer amendments could enhance the production of highly reactive minerals, for example, allophane, imogolite, and ferrihydrite, which further benefit for soil carbon storage and soil fertility improvement

    Characterization of a thermostable β-glucosidase from Aspergillus fumigatus Z5, and its functional expression in Pichia pastoris X33

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    <p>Abstract</p> <p>Background</p> <p>Recently, the increased demand of energy has strongly stimulated the research on the conversion of lignocellulosic biomass into reducing sugars for the subsequent production, and β-glucosidases have been the focus because of their important roles in a variety fundamental biological processes and the synthesis of useful β-glucosides. Although the β-glucosidases of different sources have been investigated, the amount of β-glucosidases are insufficient for effective conversion of cellulose. The goal of this work was to search for new resources of β-glucosidases, which was thermostable and with high catalytic efficiency.</p> <p>Results</p> <p>In this study, a thermostable native β-glucosidase (nBgl3), which is secreted by the lignocellulose-decomposing fungus <it>Aspergillus fumigatus </it>Z5, was purified to electrophoretic homogeneity. Internal sequences of nBgl3 were obtained by LC-MS/MS, and its encoding gene, <it>bgl3</it>, was cloned based on the peptide sequences obtained from the LC-MS/MS results. <it>bgl</it>3 contains an open reading frame (ORF) of 2622 bp and encodes a protein with a predicted molecular weight of 91.47 kDa; amino acid sequence analysis of the deduced protein indicated that nBgl3 is a member of the glycoside hydrolase family 3. A recombinant β-glucosidase (rBgl3) was obtained by the functional expression of <it>bgl</it>3 in <it>Pichia pastoris </it>X33. Several biochemical properties of purified nBgl3 and rBgl3 were determined - both enzymes showed optimal activity at pH 6.0 and 60°C, and they were stable for a pH range of 4-7 and a temperature range of 50 to 70°C. Of the substrates tested, nBgl3 and rBgl3 displayed the highest activity toward 4-Nitrophenyl-β-D-glucopyranoside (pNPG), with specific activities of 103.5 ¹ 7.1 and 101.7 ¹ 5.2 U mg<sup>-1</sup>, respectively. However, these enzymes were inactive toward carboxymethyl cellulose, lactose and xylan.</p> <p>Conclusions</p> <p>An native β-glucosidase nBgl3 was purified to electrophoretic homogeneity from the crude extract of <it>A. fumigatus </it>Z5. The gene <it>bgl</it>3 was cloned based on the internal sequences of nBgl3 obtained from the LC-MS/MS results, and the gene <it>bgl3 </it>was expressed in <it>Pichia pastoris </it>X33. The results of various biochemical properties of two enzymes including specific activity, pH stability, thermostability, and kinetic properties (Km and Vmax) indicated that they had no significant differences.</p

    A Simple and Low-Cost Strategy to Improve Conidial Yield and Stress Resistance of Trichoderma guizhouense through Optimizing Illumination Conditions

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    Light is perceived by photoreceptors in fungi and further integrated into the stress-activated MAPK HOG pathway, and thereby potentially activates the expression of genes for stress responses. This indicates that the precise control of light conditions can likely improve the conidial yield and stress resistance to guarantee the low cost and long shelf life of Trichoderma-based biocontrol agents and biofertilizers. In this study, effects of wavelengths and intensities of light on conidial yield and stress tolerance to osmotic, oxidative and pH stresses in Trichoderma guizhouense were investigated. We found that 2 μmol photons/(m2^{2} × s) of blue light increased the conidial yield more than 1000 folds as compared to dark condition and simultaneously enhanced conidial stress resistance. The enhanced conidial stress resistance is probably due to the upregulated stress-related genes in blue light, which is under the control of the blue light receptor BLR1 and the MAP kinase HOG1

    Rhizosphere phage communities drive soil suppressiveness to bacterial wilt disease

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    Publisher Copyright: © 2023, The Author(s).Background: Bacterial viruses, phages, play a key role in nutrient turnover and lysis of bacteria in terrestrial ecosystems. While phages are abundant in soils, their effects on plant pathogens and rhizosphere bacterial communities are poorly understood. Here, we used metagenomics and direct experiments to causally test if differences in rhizosphere phage communities could explain variation in soil suppressiveness and bacterial wilt plant disease outcomes by plant-pathogenic Ralstonia solanacearum bacterium. Specifically, we tested two hypotheses: (1) that healthy plants are associated with stronger top-down pathogen control by R. solanacearum-specific phages (i.e. ‘primary phages’) and (2) that ‘secondary phages’ that target pathogen-inhibiting bacteria play a stronger role in diseased plant rhizosphere microbiomes by indirectly ‘helping’ the pathogen. Results: Using a repeated sampling of tomato rhizosphere soil in the field, we show that healthy plants are associated with distinct phage communities that contain relatively higher abundances of R. solanacearum-specific phages that exert strong top-down pathogen density control. Moreover, ‘secondary phages’ that targeted pathogen-inhibiting bacteria were more abundant in the diseased plant microbiomes. The roles of R. solanacearum-specific and ‘secondary phages’ were directly validated in separate greenhouse experiments where we causally show that phages can reduce soil suppressiveness, both directly and indirectly, via top-down control of pathogen densities and by alleviating interference competition between pathogen-inhibiting bacteria and the pathogen. Conclusions: Together, our findings demonstrate that soil suppressiveness, which is most often attributed to bacteria, could be driven by rhizosphere phage communities that regulate R. solanacearum densities and strength of interference competition with pathogen-suppressing bacteria. Rhizosphere phage communities are hence likely to be important in determining bacterial wilt disease outcomes and soil suppressiveness in agricultural fields. [MediaObject not available: see fulltext.].Peer reviewe

    Resource availability modulates biodiversity-invasion relationships by altering competitive interactions

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    Community diversity affects the survival of newly introduced species via resource competition. Competitive interactions can be modulated by resource availability and we hypothesized that this may alter biodiversity-invasion relationships. To study this, we assessed the growth of a bacterial invader, Ralstonia solanacearum, when introduced into communities comprised of one to five closely related resident species under different resource concentrations. The invader growth was then examined as a function of resident community richness, species composition and resource availability. We found that the relative density of the invader was reduced by increasing resident community richness and resource availability. Mechanistically, this could be explained by changes in the competitive interactions between the resident species and the invader along the resource availability gradient. At low resource availability, resident species with a high catabolic similarity with the invader efficiently reduced the invader relative density, while at high resource availability, fast-growing resident species became more important for the invader suppression. These results indicate that the relative importance of different resident community species can change dynamically along to resource availability gradient. Diverse communities could be thus more robust to invasions by providing a set of significant species that can take suppressive roles across different environments
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