Fibers stripped from water-retted hemp stalks. (a) Manual stripping from stalks, (b) fiber bundles, (c) hemp comb and combed fibers and (d) 100% hemp sliver.

Researchers from Ege University in Türkiye say they’ve developed a controlled microbial process that extracts usable textile fiber from hemp in seven days, cutting the time required by conventional water retting roughly in half. Their findings were published in a study (PDF) in AUTEX Research Journal.

The team used bacteria isolated from hemp-retting water in the country’s Black Sea region to create a locally adapted process for separating fibers from hemp stalks. Retting breaks down the pectin that binds fiber bundles to the woody portions of the hemp stem. Traditional water retting relies on naturally occurring microorganisms, making the process difficult to control and potentially resulting in inconsistent fiber quality or damage caused by excessive retting.

Researchers selected three bacterial strains that showed strong pectin-degrading activity without detectable cellulose-degrading activity: Pantoea sp., Bacillus sp. and Clostridium beijerinckii.

The team introduced the aerobic Pantoea and Bacillus strains at the beginning of the process before adding the anaerobic C. beijerinckii strain on the fourth day. The staged approach was designed to replicate the natural transition from aerobic to anaerobic microbial activity during retting.

The microbial method produced higher concentrations of reducing sugars than conventional retting, indicating greater breakdown of the pectin-rich materials surrounding the fibers. Researchers determined that seven days provided the best balance of fiber yield, waste reduction and suitability for spinning.

The resulting hemp fibers were blended with cotton and successfully spun into Ne 12/1 yarn using an open-end rotor spinning system. Fibers collected at other processing times and those produced through the conventional method could not be spun under the study’s test conditions because of repeated yarn breakages.

The microbiologically retted fibers were somewhat darker and had slightly lower tenacity than conventionally retted fibers, but they were longer, easier to remove from the stalk and described as softer.

The researchers said the study marks the first reported use of Pantoea species and Clostridium beijerinckii in hemp retting, while demonstrating that locally sourced microorganisms may support faster production of textile-grade hemp fiber.