The degradation process of flax fibres is the same for both ancient and modern objects made from this polysaccharidic material. With time, the geographic area of production and cultivation has changed, as have the applications of flax fibres from clothing to sails and paintings from antiquity, to automotive, fashion, and design applications in the contemporary era. (2016).įlax fibres have been used by humans for approximately 10,000 years. This part was adapted from Polizeli et al. Keys indicate sugar monomers making up polymers (top frame) and cell wall degrading enzyme activities (bottom frame). (C) Examples of different cell wall polymers: Rhamnogalactan I (RGI) pectin (left), xyloglucan hemicellulose (middle), and cellulose (right). At over-retting, the secondary cell wall of fibers starts to become degraded (right). All cell wall layers are intact at the start of retting (left), at optimal retting stage (middle) the middle lamella and primary cell walls of cortical parenchyma cells are degraded (green/orange) and the middle lamella between neighboring fiber cells is starting to become degraded (green/orange). (B) Schematic representation of the different layers of a plant cell wall: middle lamella (ML), primary cell wall (PW), secondary cell wall (SW), S1 and S2 layers of the secondary cell wall (S1, S2). At optimal retting cortical parenchyma cells are no longer visible and fiber bundle dissociation has started. Appearance of a stem cross-section from a freshly up-rooted plant at the beginning of retting (left), at the optimal retting (middle), and over-retted (right). (A) Microphotographs illustrating progressive changes in flax stem morphology during retting. | Multiscale presentation of retting process in flax. In this paper we review how our current knowledge of the microbiology of retting has been improved by targeted metagenomics and discuss how related ‘-omics’ approaches might be used to fully characterize the functional capability of the retting microbiome. Recent advances in sequencing technology have allowed researchers to implement targeted metagenomics leading to a much better characterization of the microbial communities involved in retting, as well as an improved understanding of microbial dynamics. During this process microorganisms colonize the stem and produce hydrolytic enzymes that target cell wall polymers thereby facilitating the progressive destruction of the stem and fiber bundles. One important factor is the post-harvest process known as retting, representing the first step in the extraction of bast fibers from the stem of species such as flax and hemp. A better understanding of how all these factors exert their effect and how they interact is necessary to be able to optimize fiber quality for use in different industries. The mechanical and chemical properties of natural plant fibers are determined by many different factors, both intrinsic and extrinsic to the plant, during growth but also after harvest.
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