Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: Integrated Crop, Soil, and Water Management Systems for Sustainable Production of Sugarcane for Bioenergy Feedstock

Location: Sugarcane Research Unit

Title: Investigation of the microbial retting community of kenaf (Hibiscus cannabinus) under differing conditions using next-generation semiconductor sequencing

Authors
item Visi, David -
item D'Sourza, Nandika -
item Ayre, Bryan -
item Webber, Charles
item Allen, Michael -

Submitted to: Journal of Industrial Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 5, 2013
Publication Date: May 1, 2013
Citation: Visi, D.K., D'Sourza, N., Ayre, B.G., Webber III, C.L., Allen, M.S. 2013. Investigation of the microbial retting community of kenaf (Hibiscus cannabinus) under differing conditions using next-generation semiconductor sequencing. Journal of Industrial Microbiology and Biotechnology.40(5):465-475.

Interpretive Summary: The transition to a green, bio-based economy necessitates changing more than just sources for liquid transportation fuels. One possible green alternative is the substitution of plant fibers for fiberglass in the production of high-value, green composite materials. The use of the natural fibers requires the development of cost-efficient processing of fibers with consistent, uniform properties. Research was conducted to determine the microbial communities involved in the “natural” retting of kenaf (Hibiscus cannabinus) fibers and explore viable options for increasing the efficiency of the retting process by altering the microbial communities. Microbial communities were identified by semiconductor sequencing of 16S rRNA gene amplicons from DNA harvested from plant-surface associated samples and analyzed using an Ion Torrent PGM. The communities were sampled after 96 hours from each of three different conditions, including amendments with pond water, sterilized pond water, or with a mixture of pectinolytic bacterial isolates. Additionally, plants from two different sources having different pretreatment conditions were compared. We report that the best retting communities are dominated by members of the order Clostridiales. These bacteria appear to be naturally associated with the plant material, although slight variations between source materials were found. Additionally, heavy inoculations of pectinolytic bacteria failed to establish themselves on the plant material surface, but their presence facilitated the rapid dominance of the original plant-associated Clostridiales. These data suggest that members of the order Clostridiales dominate the community and are most closely associated with efficient and effective retting. The results further suggest that establishment of the community structure is first driven by the switch to anaerobic conditions, and subsequently by possible competition for nitrogen. These findings reveal important bacterial groups involved in fiber retting, and suggest mechanisms for the manipulation of the community and retting efficiency by modifying nutrient availability.

Technical Abstract: The use of the natural fibers requires the development of cost-efficient processing of fibers with consistent, uniform properties. The microbial communities associated with kenaf (Hibiscus cannabinus) plant fibers during retting were determined in an effort to identify possible means of accelerating this process for industrial scale-up. Microbial communities were identified by semiconductor sequencing of 16S rRNA gene amplicons from DNA harvested from plant-surface associated samples and analyzed using an Ion Torrent PGM. The communities were sampled after 96 hours from each of three different conditions, including amendments with pond water, sterilized pond water, or with a mixture of pectinolytic bacterial isolates. Additionally, plants from two different sources having different pretreatment conditions were compared. We report that the best retting communities are dominated by members of the order Clostridiales. These bacteria appear to be naturally associated with the plant material, although slight variations between source materials were found. Additionally, heavy inoculations of pectinolytic bacteria failed to establish themselves on the plant material surface, but their presence facilitated the rapid dominance of the original plant-associated Clostridiales. These data suggest that members of the order Clostridiales dominate the community and are most closely associated with efficient and effective retting. The results further suggest that establishment of the community structure is first driven by the switch to anaerobic conditions, and subsequently by possible competition for nitrogen. These findings reveal important bacterial groups involved in fiber retting, and suggest mechanisms for the manipulation of the community and retting efficiency by modifying nutrient availability.

Last Modified: 4/24/2014
Footer Content Back to Top of Page