ARS | Publication request: Production of Highly Active Lignocellulose-Degrading Enzymes of Anaerobic Fungi by Industrially Relevant Fungi

Submitted to: Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: March 3, 2007
Publication Date: March 3, 2007
Citation: Li, X., Skory, C.D., Ximenes, E.A., Jordan, D.B., Dien, B.S., Hughes, S.R., Cotta, M.A. 2007. Production of highly active lignocellulose-degrading enzymes of anaerobic fungi by industrially relevant fungi [abstract].

Technical Abstract: Most anaerobic fungi isolated from the digestive tracts of herbivorous animals secrete highly active lignocellulose-degrading enzymes, but the levels of production are usually low (e.g., <50 mg per liter). Fungi such as Trichoderma and Aspergillus, that are commonly used for commercial production of enzymes, are able to secrete proteins with yields over 50 grams per liter. To couple the advantages of highly active enzymes of anaerobic fungi with the high-yield protein production capacity by the industrial relevant fungi, one must develop procedures to over-express the anaerobic fungal enzymes using either Trichoderma or Aspergillus production systems. We have recently succeeded in over-expressing the xylanase A gene of the polycentric anaerobic fungus Orpinomyces PC-2 in T. reesei Rut C-30. The strategies employed for expression and secretion of the highly active xylanase include fusing an inducible promoter to native protein domain-coding sequences, increasing the G+C content, engineering specific protease-cleavage sites, and raising the pH of the production medium. The recombinant xylanase displayed a specific activity and other characteristics very attractive to lignocellulosic conversion and other industrial applications. Work is underway to optimize process parameters for bioreactor production of the xylanase.