Bacterial retting of bast-fibers: when tundra soil meets nettle staks
BARET
The demand of natural fibers is continuously increasing in textile and biocomposite industries.
Nettle, like hemp and flax, contains bast-fibers occurring as bundles in the outer part of the stem. Nettle fibers were traditionally used for textile. It is an attractive candidate for natural fiber production with little cultivation and pesticide need, and it is perennial which reduces the annual production costs.
The first step of fiber extraction, or retting, consists in the degradation of pectin, hemicellulose and lignin to release the bundles and the individual fibers. Retting is a major limiting step for efficient and high-quality natural fiber production (Yu et al 2019, DOI 10.1016/B978-0-08-102632-8.00001-3). It can be done mechanically, chemically or naturally by soil or water microorganisms where it is dependent on local climate. The use of purified enzymes has been tested in the past but are too costly. Recently, microbial retting has been developed and appears as the cleanest and fastest method to produce high quality fibers (Lee et al 2020, DOI 10.1155/2020/6074063).
In BARET, our goal is to test and select bacterial strains suitable for bacterial retting of nettle, and also possibly other bast-fiber plants. Potential bacteria strains will be screened out from the Luke ARMI bacterial collection, originating from tundra soil.
BARET is a sister project of ARKNOKK (Arktinen Nokkonen), an EAKR-funded project aiming at promoting a nettle value chain in Lapland.
Our tools:
- The Luke's ARMI bacterial collection: a collection of more than 900 strains isolated from Arctic environments
- the running ARKNOKK project, in which northern nettle ecotypes are selected, analyzed and cultivated
- Luke's expertise and know-how
The concrete outcome of BARET is the selection of bacterial strain(s) suitable for bacterial retting of nettle, and possible other bast-fiber plants.
Preliminary retting test will be done with Finnish nettle to confirm the applicability of the method but no ready-to-use protocol for bacterial retting can be proposed by the end of BARET (one year-project). The aim of BARET is to propose a tool and show its potentiality for bacterial retting of bast-fiber plants. Further research will be needed for optimization of retting conditions. BARET is a starting point of developing a green chemistry technology for sustainable production of natural fibers.
