Bioconversion of forest products industry waste cellulosics to fuel ethanol: a review.

Cellulose degrading enzymes and their potential industrial applications.

The hypersecreting mutant Trichoderma reesei RUT-C30 (ATCC 56765) is one of the most widely used strains of filamentous fungi for the production of cellulolytic enzymes and recombinant proteins, and for academic research. The strain was obtained after three rounds of random mutagenesis of the wild-type QM6a in a screening program focused on high cellulase production and catabolite derepression. Whereas RUT-C30 achieves outstanding levels of protein secretion and high cellulolytic activity in comparison to the wild-type QM6a, recombinant protein production has been less successful. Here, we bring together and discuss the results from biochemical-, microscopic-, genomic-, transcriptomic-, glycomic- and proteomic-based research on the RUT-C30 strain published over the last 30 years.

Trichoderma reesei RUT-C30--thirty years of strain improvement.

(1985). The Properties of Fungal and Bacterial Cellulases with Comment on their Production and Application. Biotechnology and Genetic Engineering Reviews: Vol. 3, No. 1, pp. 39-110.

https://www.tandfonline.com/doi/pdf/10.1080/02648725.1985.10647809

The Properties of Fungal and Bacterial Cellulases with Comment on their Production and Application

Bleaching of hardwood kraft pulp by Trametes versicolor was accompanied by release and accumulation of methanol, which was produced by demethylation of the pulp. A partial demethylation of the pulp was observed with isolated laccase I from T. versicolor. The extent of demethylation by laccase was increased to the level released by the fungus by addition of 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS). Methanol release by the laccase/ABTS combination was followed by slower kappa reduction. Both methanol release and kappa reduction were dependent on laccase and ABTS concentrations. The fungus did not produce a stable equivalent of ABTS during bleaching, because extracellular culture fluid from bleaching cultures gave only the same methanol release from pulp as laccase I. Pulp viscosity, an indicator of cellulose chain length, was decreased only slightly by laccase. Thus the enzyme in the presence of ABTS, unlike the fungus, specifically attacks lignin.

Demethylation and delignification of kraft pulp by Trametes versicolor laccase in the presence of 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate)

A filter paper assay method and unit value is described for the measurement of enzyme saccharification action. The method is simple, reproducible, and quantitative and predicts enzyme action under practical saccharification conditions. (JSR)

Measurement of saccharifying cellulase.

Productivity in a cellulase fermentation can be improved by optimization of media and fermentation conditions and by strain improvement, which enables us to alleviate or circumvent the genetic and metabolic controls that reduce or limit enzyme synthesis. T. reesei is the best organism to use for cellulase production because it produces high levels of a stable and complete cellulase complex. The wild strain produces little cellulase because of the restrictions placed on cellulase synthesis by genetic and metabolic controls. The mutant strains with enhanced cellulase productivity metabolic controls. The mutant strains with enhanced cellulase productivity AM 9414 and NG 14 are also subject to catabolite repression. With these mutants the best yields are attained when growth is good but restrained by substrate limitation or low pH. The results obtained in using new improved strains of T. reesei were discussed. High cellulase productivity was attained by using 6% two-roll milled cotton which contains about 80% fairly susceptible cellulose and about 20% residue that is very resistant to cellulase. The mutant strains grow rapidly on the susceptible portions of the cellulose, producing mostly biomass, and then continue hydrolyzing the resistant fraction of the cellulose with active enzyme production over a 14-day period,more » which results finally in broths containing up to 2% extracellular protein. Strain MCG 77 gives yields similar to the other enhanced mutant strains QM 9414 and NG 14 in regular cellulase fermentations. However, this strain grows rapidly on soluble substrates without subsequent restrictions in celllulase synthesis and has a faster rate of metabolism and enzyme production. 8 figures, 3 tables.« less

R. Andreotti

Papers

Measurement of saccharifying cellulase.

Cellulase production by a new mutant strain of Trichoderma reesei MCG77