Topic
Xylanase
About: Xylanase is a research topic. Over the lifetime, 7099 publications have been published within this topic receiving 163793 citations.
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TL;DR: Analysis of P. ostreatus tomato SSF samples by zymogram revealed two bands with laccase activity which had not been detected so far, being higher than those reported for the fungi typically considered as the best protease producers such as Aspergillus strains.
Abstract: A process of solid state fermentation (SSF) on tomato pomace was developed with the white-rot fungi Pleurotus ostreatus and Trametes versicolor, using sorghum stalks as support. Operative parameters (humidity, water activity, and size of substrate particles) guaranteeing a good colonization of tomato pomace by both fungi were defined and conditions for production at high titers of the industrially relevant enzymes laccase, xylanase and protease were identified. Significant laccase activity levels (up to 36 U g−1 dry matter) were achieved without any optimization of culture conditions, neither by nutrient addition nor by O2 enrichment. Furthermore, protease activity levels up to 34,000 U g−1 dry matter were achieved, being higher than those reported for the fungi typically considered as the best protease producers such as Aspergillus strains. Moreover, as one of the most significant results of this study, analysis of P. ostreatus tomato SSF samples by zymogram revealed two bands with laccase activity which had not been detected so far.
58 citations
TL;DR: Of the fungal isolates tested, Aspergillus niger A-20 proved to be the most potent and produced highly active multienzyme systems after 5 days in shaken cultures, suggesting potential uses in the extraction of the major components of plant materials.
58 citations
TL;DR: The two genes of B. stearothermophilus 21 appear to be, at least partly, expressed independently, which was experimentally confirmed in E. coli by deletion analysis.
Abstract: Bacillus stearothermophilus 21 is a gram-positive, facultative thermophilic aerobe that can utilize xylan as a sole source of carbon. We isolated this strain from soil, purified its extracellular xylanase and beta-xylosidase, and analyzed the two-step degradation of xylan by these enzymes (T. Nanmori, T. Watanabe, R. Shinke, A. Kohno, and Y. Kawamura, J. Bacteriol. 172:6669-6672, 1990). An Escherichia coli transformant carrying a 4.2-kbp chromosomal segment of this bacterium as a recombinant plasmid was isolated. It excreted active beta-xylosidase and xylanase into the culture medium. The plasmid was introduced into UV-sensitive E. coli CSR603, and its protein products were analyzed by the maxicell method. Proteins harboring beta-xylosidase and xylanase activities were identified, and their molecular masses were estimated by sodium dodecyl sulfate-polyarylamide gel electrophoresis to be 75 and 40 kDa, respectively. The values were identical to those of proteins prepared from cells of B. stearothermophilus 21. The genes for both enzymes were encoded in a 3.4-kbp PstI fragment derived from the 4.2-kbp chromosomal segment. The nucleotide sequence of the 4.2-kbp segment was accordingly determined. The beta-xylosidase gene (xylA) is located upstream of the xylanase gene (xynA) with a possible promoter and a Shine-Dalgarno sequence. The latter gene is preceded by two possible promoters and a Shine-Dalgarno sequence that are located within the 3'-terminal coding region of the former. The two genes thus appear to be, at least partly, expressed independently, which was experimentally confirmed in E. coli by deletion analysis.(ABSTRACT TRUNCATED AT 250 WORDS)
58 citations
TL;DR: This is the first report of a xylanase able to induce hypersensitive-like symptoms on a monocot plant, and showed about 40% reduction of xylan enzyme activity in comparison to the wild type when grown in culture with xylan as carbon source.
58 citations
TL;DR: In this paper, a series of experiments were completed to investigate the impact of addition of enzymes at ensiling on in vitro rumen degradation of maize silage, and two commercial products, Depol 40 (D, Biocatalysts Ltd., Pontypridd, UK) and Liquicell 2500 (L, Specialty Enzymes and Biochemicals, Fresno, CA, USA), were used.
58 citations