8-61: A Trichoderma gamsii mutant with enhanced production of cellulases for enzymatic degradation of bagasse pulp

We describe attempts to develop cellulase-producing Trichoderma strains, using the final target substrate throughout the screening, as opposed to commonly used artificial substrates. Thus, bagasse pulp from Borregaard’s BALI process was used as substrate in all evaluation steps. 108 wild type Trichoderma isolates were evaluated by agar diffusion assays in tubes. Nine isolates were selected for a second screen in shake flasks, using bagasse pulp as the only carbon source. Cellulolytic activities of culture supernatants were evaluated with a DNS method, again using the bagasse pulp as the substrate. Trichoderma gamsii isolate T40 proved to be the most promising extracellular cellulase producer and was therefore chosen for further improvement by mutagenesis. Trichoderma gamsii mutants were obtained using UV-light as mutagen, whereas screening was done using a plate clearing assay on bagasse pulp agar and subsequent evaluation in shake flask cultures. The mutant strain with the highest capability to produce bagasse-pulp saccharifying activity was evaluated in lab-scale fermenters and cellulase levels were compared with those of the parent strain and of Trichoderma reesei RUT-C30.