Elucidating Field Retting Mechanisms of Hemp Fibres for Biocomposites: Effects of Microbial Actions and Interactions on the Cellular Micro-morphology and Ultrastructure of Hemp Stems and Bast Fibres

Dinesh Fernando, Anders Thygesen, Anne S. Meyer, Geoffrey Daniel


Field retting is an industrial process for extracting valuable bast fibres from hemp. In this study, molecular, chemical, and scanning electron microscopy studies were employed to understand the field retting mechanisms involving microbiota, including microbial community dynamics, hemp colonization, functions/interactions, and hemp biodegradation. This study for the first time revealed the coexistence of bacterial-fungal interactions during retting and showed progressive microbial breakdown of the stems. Using scanning electron microscopy, evidence for microbial activities/interactions within the stems was obtained, which helped to understand hemp retting mechanisms. The collective findings showed that: a) initially, easily accessible food within the hemp stems attracted and supported microbial invasion and decay, with activities influenced by the stem anatomy, chemistry, and morphology; b) filamentous fungi as key players in the early stages remarkably contributed to efficient fibre defibration; c) extended retting enhanced the bacterial activities, including bacterial-fungal interactions and their dominant role within the community; d) bacterial attraction and activities were promoted by bacterial mycophagy with a set of different phenotypic behaviours for nutrients and fungal highways for transport within the stems; and e) bast fibre degradation leading to inferior quality during prolonged retting was caused by ultrastructural modifications to all of the major fibre cell wall layers.


Bacterial-fungal interactions (BFIs); Bacterial mycophagy; Fibre cell wall ultrastructure; Field retting; Hemp fibres; Microbial dynamics; Scanning electron microscopy (SEM)

Full Text:


Welcome to BioResources! This online, peer-reviewed journal is devoted to the science and engineering of biomaterials and chemicals from lignocellulosic sources for new end uses and new capabilities. The editors of BioResources would be very happy to assist you during the process of submitting or reviewing articles. Please note that logging in is required in order to submit or review articles. Martin A. Hubbe, (919) 513-3022, hubbe@ncsu.edu; Lucian A. Lucia, (919) 515-7707, lucia-bioresources@ncsu.edu URLs: bioresourcesjournal.com; http://ncsu.edu/bioresources ISSN: 1930-2126