FAIR-CT96-5016 Potential for upgrading lignocellulosic material by treatment with enzyme demand from rumen bacterial genes

Contacts




To find similar Items, click on a keyword below:
Biological Conversion : FAIR Area 2.2 - Bioprocessing : FAIR Marie Curie Research Training Grants : Fine Chemicals

Objectives:

The utilisation of lignocellulosic material in agricultural and industrial processes can be enhanced by treatment with plant cell wall degrading enzymes. Cloned genes potentially allow the production of specific enzymes with desirable properties economically and in large quantities. Rumen bacteria are a source of plant cell wall degrading enzymes that could prove particularly valuable for improving the digestibility of plant material by farm animals. Many genes coding for these enzymes have been isolated from rumen bacteria in the host laboratory. This project aimed to examine the functional properties and potential applications of an unique bifunctional hemicellulase, XynD, from Ruminococcus flavefaciens and to enhance expression of the cloned XynD gene by introducing it into lactic acid bacteria. It was also proposed to isolate further valuable genes that lie next to XynD in the bacterial chromosome.

Activities and Results:

Initial work established that the bacterium produced inducible esterases when grown with xylans as the energy source. Clones that express activity against model esterase substrates (alpha-napthyl acetate) were isolated from a R. flavefaciens 17 DNA library. One clone has subsequently been shown to encode an enzyme that can deacetylate acetylated plant xylans. A second component of the project involved sequence analysis of a region of DNA downstream from the xynD gene in R. Flavefaciens in order to locate genes coding for additional debranching activities. This is known to encode alpha-arabinosidase activity. The gene most likely to account for the alpha-arabinosidase activity is a family 3 glycoside hydrolase that may function primarily as a beta-(I,4)-xylosidase, although an adjacent ORF is also present that does match a database entry.

Conclusion:

The region downstream of xynD has been shown to encode a gene cluster responsible for the utilisation of xylan breakdown products.

Keywords: esterase, xylan

Contacts

Scientific Supervisor

• Harry FLINT / Rowett Research Institute Division of Nutritional Sciences / UNITED KINGDOM