Novel Xylanase from a Holstein Cattle Rumen Metagenomic Library and Its Application in Xylooligosaccharide and Ferulic Acid Production from Wheat Straw
ABSTRACT A novel gene fragment containing a xylanase was identified from a Holstein cattle rumen metagenomic library. The novel xylanase (Xyln-SH1) belonged to the glycoside hydrolase family 10 (GH10) and exhibited a maximum of 44% identity to the glycoside hydrolase from Clostridium thermocellum ATCC 27405. Xyln-SH1 was heterologously expressed, purified and characterized. A high level of activity was obtained under the optimum conditions of pH 6.5 and 40°C. A substrate utilization study indicated that Xyln-SH1 was cellulase-free and strictly specific to xylan from softwood. The synergistic effects of Xyln-SH1 and feruloyl esterase (FAE-SH1) were observed for the release of xylooligosaccharides (XOS) and ferulic acid (FA) from wheat straw. In addition, a high dose of Xyln-SH1 alone was observed to improve the release of FA from wheat straw. These features suggest that this enzyme has substantial potential to improve biomass degradation and industrial applications.
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ABSTRACT: Amycolatopsis sp. ATCC 39116 (formerly Streptomyces setonii) has shown promising results in converting ferulic acid (substrate), which can be derived from natural plant wastes, to vanillin. After exploring the influence of adding vanillin at different times during the growth cycle on cell growth and transformation performance of this strain, and demonstrating the inhibitory effect of vanillin, a solid-liquid Two-Phase Partitioning Bioreactor (TPPB) system was used as an in situ product removal technique to enhance transformation productivity by this strain. The thermoplastic polymer Hytrel(®) G4078W was found to have superior partitioning capacity for vanillin with a partition coefficient of 12, and a low affinity for the substrate. A 3 L working volume solid-liquid fed-batch TPPB mode, using 300 g Hytrel(®) G4078W as the sequestering phase, produced a final vanillin concentration of 19.5 g/L. The overall productivity of this reactor system was 450 mg/L·h, among the highest reported in literature. Vanillin was easily and quantitatively recovered from the polymers mostly by single stage extraction into methanol or other organic solvents used in food industry, simultaneously regenerating polymer beads for re-use. A polymer-liquid two phase bioreactor was again confirmed to easily outperform single phase systems that feature inhibitory or easily further degraded substrates/products. This enhancement strategy might reasonably be expected in the production of other flavour and fragrance compounds obtained by biotransformations. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 2013.Biotechnology Progress 01/2014; 30(1). DOI:10.1002/btpr.1830 · 1.88 Impact Factor
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ABSTRACT: Traditional use of enzymes for food processing and production of food ingredients resulted in fast-growing enzyme industries world over. The advances in technologies gave rise to exploring newer enzymes and/or modified enzymes for specific application. Search for novel enzymes that can augment catalytic efficiency and advances in molecular biology techniques including sequencing has targeted microbial diversity through metagenomic approaches for sourcing enzymes from difficult to culture organisms. Such mining studies have received more attention in characterizing hydrolases, their prevalence, broad substrate specificities, stability, and independence of cofactors. The focus on glycosyl hydrolases from metagenome for their application in food sector is reviewed.Journal of Food Science 10/2014; 79(11). DOI:10.1111/1750-3841.12677 · 1.79 Impact Factor
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ABSTRACT: Metagenomics deals with the isolation of genetic material directly recovered from environmental samples. Metagenomics as an approach has emerged over the past two decades to elucidate a host of microbial communities inhabiting a specific niche with the goal of understanding their genetic diversity, population structure, and ecological role played by them. A number of new and novel molecules with significant functionalities and applications have been identified through this approach. In fact, many investigators are engaged in this field to unlock the untapped genetic resources with funding from governments sector. The sustainable economic future of modern industrialized societies requires the development of novel molecules, enzymes, processes, products, and applications. Metagenomics can also be applied to solve practical challenges in the field of medicine, agriculture, sustainability, and ecology. Metagenomics promises to provide new molecules and novel enzymes with diverse functions and enhanced features compared to the enzymes from the culturable microorganisms. Besides the application of metagenomics for unlocking novel biocatalysts from nature, it also has found applications in fields as diverse as bioremediation, personalized medicine, xenobiotic metabolism, and so forth.08/2014; 2014:1-7. DOI:10.1155/2014/146030