Actinomycete enzymes and activities involved in straw saccharification
This research programme has been directed towards the analysis of actinomycete enzyme systems involved in the degradation of plant biomass (lignocellulose). The programme was innovative in two respects: a novel source of enzymes, ie. actinomycetes, was systematically screened; wheat straw saccharifying activity, rather than the production of particular enzymes, was the criterion used. Over 200 actinomycete strains representing a broad taxonomic range were screened. Common features included optimal saccharifying activity in the pH range 6-9, and the identification of xylose oligomers as the principal products. Increased stability at 70 C was a feature of enzyme preparations from thermophilic strains. A range of specific enzyme activities was involved and included cellulase, xylanase, arabinofuranosidase, acetylesterase, beta-xylosidase and beta-glucosidase. With the exception of the latter two enzymes, saccharifying activity was mainly located in culture supernatants. Evidence for activity against the lignin fraction of straw was produced for a range of actinomycete strains. While modification reactions were common, cleavage of inter-monomer bonds, and utilisation of complex polyphenolic compounds were restricted to two strains. Many actinomycetes demonstrated the ability to solubilise lignocarbohydrate; this phenomenon is therefore not related to direct depolymerisation of native lignin. The enzyme binding and stabilisation properties of this complex are potentially exploitable, and its generation probably results from the cooperative action of several enzyme activities, both oxidative and hydrolytic.
Bibliographic Reference: EUR 12929 EN (1990) 27 pp., MF, ECU 4, blow-up copy ECU 5
Record Number: 199011573 / Last updated on: 1994-12-02
Original language: en
Available languages: en