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- Mohan Pawar, Prashant, et al.
(författare)
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Expression of fungal acetyl xylan esterase in Arabidopsis thaliana improves saccharification of stem lignocellulose
- 2016
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Ingår i: Plant Biotechnology Journal. - : Wiley. - 1467-7644 .- 1467-7652. ; 14:1, s. 387-397
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Tidskriftsartikel (refereegranskat)abstract
- Cell wall hemicelluloses and pectins are O-acetylated at specific positions, but the significance of these substitutions is poorly understood. Using a transgenic approach, we investigated how reducing the extent of O-acetylation in xylan affects cell wall chemistry, plant performance and the recalcitrance of lignocellulose to saccharification. The Aspergillus niger acetyl xylan esterase AnAXE1 was expressed in Arabidopsis under the control of either the constitutively expressed 35S CAMV promoter or a woody-tissue-specific GT43B aspen promoter, and the protein was targeted to the apoplast by its native signal peptide, resulting in elevated acetyl esterase activity in soluble and wall-bound protein extracts and reduced xylan acetylation. No significant alterations in cell wall composition were observed in the transgenic lines, but their xylans were more easily digested by a beta-1,4-endoxylanase, and more readily extracted by hot water, acids or alkali. Enzymatic saccharification of lignocellulose after hot water and alkali pretreatments produced up to 20% more reducing sugars in several lines. Fermentation by Trametes versicolor of tissue hydrolysates from the line with a 30% reduction in acetyl content yielded similar to 70% more ethanol compared with wild type. Plants expressing 35S: AnAXE1 and pGT43B:AnAXE1 developed normally and showed increased resistance to the biotrophic pathogen Hyaloperonospora arabidopsidis, probably due to constitutive activation of defence pathways. However, unintended changes in xyloglucan and pectin acetylation were only observed in 35S: AnAXE1-expressing plants. This study demonstrates that postsynthetic xylan deacetylation in woody tissues is a promising strategy for optimizing lignocellulosic biomass for biofuel production.
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| 2. |
- Zamora-Ros, Raul, et al.
(författare)
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Dietary polyphenol intake in europe : The european prospective investigation into cancer and nutrition (EPIC) study
- 2016
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Ingår i: European Journal of Nutrition. - : Springer Science and Business Media LLC. - 1436-6207 .- 1436-6215. ; 55:4, s. 1359-1375
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Tidskriftsartikel (refereegranskat)abstract
- Background/Objectives Polyphenols are plant secondary metabolites with a large variability in their chemical structure and dietary occurrence that have been associated with some protective effects against several chronic diseases. To date, limited data exist on intake of polyphenols in populations. The current cross-sectional analysis aimed at estimating dietary intakes of all currently known individual polyphenols and total intake per class and subclass, and to identify their main food sources in the European Prospective Investigation into Cancer and Nutrition cohort. Methods Dietary data at baseline were collected using a standardized 24-h dietary recall software administered to 36,037 adult subjects. Dietary data were linked with Phenol- Explorer, a database with data on 502 individual polyphenols in 452 foods and data on polyphenol losses due to cooking and food processing. Results Mean total polyphenol intake was the highest in Aarhus—Denmark (1786 mg/day in men and 1626 mg/day in women) and the lowest in Greece (744 mg/day in men and 584 mg/day in women). When dividing the subjects into three regions, the highest intake of total polyphenols was observed in the UK healthconscious group, followed by non-Mediterranean (non- MED) and MED countries. The main polyphenol contributors were phenolic acids (52.5–56.9 %), except in men from MED countries and in the UK health-conscious group where they were flavonoids (49.1–61.7 %). Coffee, tea, and fruits were the most important food sources of total polyphenols. A total of 437 different individual polyphenols were consumed, including 94 consumed at a level [1 mg/day. The most abundant ones were the caffeoylquinic acids and the proanthocyanidin oligomers and polymers. Conclusion This study describes the large number of dietary individual polyphenols consumed and the high variability of their intakes between European populations, particularly between MED and non-MED countries.
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