Fungi Trichoderma

The filament thickness can be another interesting feature. Production of cephalosporin by Cephalosporium acremonium has been observed in conjunction with some swelling of the hyphae [152]. It has been often reported that, when cultivated on solid substrate, apical parts of filamentous species tend to become thinner, apparently due to substrate limitation, which induces the cell to increase its surface to volume ratio. Similar behavior has been observed in suspended media on fungi (Trichoderma reesei [151] and S. ambofaciens [153, 154]) (Fig. 24). Hyphae are often regarded as solid cylinders, and, in order to... 

Figure 1. Hydrolysis of cotton by organisms and by cell-free enzymes (17). Growth tests—Consumption of cellulose by active cellulolytic fungi. Trichoderma enzyme— - weight loss of cellulose). Other enzymes—Cell-free celluloses from organisms other than Trichoderma...

Mach RL, Zeilinger S (2003) Regulation of gene expression in industrial fungi Trichoderma. Appl Microbiol Biotechnol 60 515-522... 

In the treatment of cellulose pulps one essential criterion for a suitable enzyme preparation is that its cellulase activity should be as low as possible, or preferably absent completely. As even extremely low cellulase activities may ruin pulp quality, Trichoderma enzyme preparations are unlikely to be suitable for these applications. Many bacterial and fungal enzymes with low cellulase activity have been shown to be suitable for treatment of pulps 14, 15, 16,17), Regulation of the often synchronous production of cellulolytic and hemicellulolytic enzymes in micro-organisms is not well understood, and is further complicated by substrate cross-specificity of these enzymes. Enzymes with both endoglucanase and xylanase activity have been reported for bacteria 18, 19) and fungi 20, 21, 22), In addition to selection of strain and... 

Cellulase-Negative Xylanase-Positive Mutants. There are two reports concerning the selection of such mutants from filamentous fungi, one on Pofyporus adm-tus (32) and the other cmi Trichoderma reesei (Durand, H. et al. Society CAYLA, Toulouse, France, unpublished results). An analysis of the eliminated cellulase genes has not been done, so it is not known if the mutants negative in endo(l- 4)-p-glucan-ase were deficient also in cellobiohydrolases. 

An antibiotic inhibition zone often appears around Trichoderma spp. interacting with other fungi. The genus contains many species which produce secondary metabolites. Claydon et al. (23) have identified an antibiotic from T. harzianum as a volatile, 6-n-pentyl-2H-pyran-2-one this was recently shown to be an active antibiotic from T. koningii (24). The volatile appeared to be the factor responsible for the coconut smell of some biocontrol-effective strains of T. harzianum (25). However, in a Petri-plate assay, it can be difficult to be certain that antibiosis is involved. As well as competitive growth, lytic enzymes could also contribute to the action and Trichoderma has been shown to produce / -l,3-glucanase and chitinase (26-29). 

It has been proposed that the production of xylanases and cellulases is under separate regulatory control in some filamentous fungi (1). Hrmova et al. (42) reached a similar conclusion after monitoring the daily production of these enzymes in Trichoderma reesei QM 9414. Xylanase and cellulase activities followed independent production profiles during fungal growth. The same effect has been observed in batch cultures of T. harzianum. We have observed peak xylanase activity on the third day of growth whereas the cellulase activity peaked after day five or six (unpublished). 

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