Process technological effects of deletion and amplification of hydrophobins I and II in transformants of Trichoderma reesei

Abstract

Transformants of the Trichoderma reeseistrains QM9414 and Rut-C30 were constructed in which the genes for the two major hydrophobin proteins, hydrophobins I (HFBI) and II (HFBII), were deleted or amplified by molecular biological techniques. Growth parameters and foam production of the transformant strains were compared with the corresponding properties of the parent strains by cultivation in laboratory bioreactors under conditions of catabolite repression (glucose medium) or induction of cellulolytic enzymes and other secondary metabolites (cellulose and lactose media). All the transformed strains exhibited vegetative growth properties similar to those of their parent. The Delta hfb2 (but not the Delta hfb1) transformant showed reduced tendency to foam, whereas both strains overproducing hydrophobins foamed extensively, particularly in the case of HFBII. Enzyme production on cellulose medium was unaltered in the Delta hfb2 transformant VTT D-99676, but both the Delta hfb2 and HFBII-overproducing transformants exhibited somewhat decreased enzyme production properties on lactose medium. Production of HFBI by the multi-copy transformant VTT D-98692 was almost 3-fold that of the parent strain QM9414. Overproduction of HFBII by the transformant VTT D-99745, obtained by transformation with three additional copies of the hfb2 gene under the cbh1 promoter, was over 5-fold compared to production by the parent strain Rut-C30. The Delta hfb2transformant VTT D-99676 produced a greatly increased number of spores on lactose medium compared with the parent strain, whereas the HFBII-overproducing transformant VTT D-99745 produced fewer spores.

Unravelling the molecular basis for light modulated cellulase gene expression - the role of photoreceptors in Neurospora crassa

“…Although hydrophobins are not known to have a major influence in cellulase efficiency [54], deletion of the strongly regulated NCU08192 (related to the M. grisea hydrophobin MHP1 [55], cluster 4), that showed increased expression levels in both white collar mutants, unexpectedly had significantly increased specific cellulase activity (Figure 7). A strain containing a mutation in another hydrophobin-like protein belonging to cluster 2 ( ccg-14 /NCU07787), encoding a ceratoplatanin-like small protein [56,57] displayed cellulolytic activity indistinguishable from WT (Figure 7).…”

Evolutionary compromises in fungal fitness: hydrophobins can hinder the adverse dispersal of conidiospores and challenge their survival

“…HFBs are also involved in symbiotic interactions, such as those between lichens and mycorrhizae [ 24 , 25 ]. HFBs play a role in development and morphogenesis in the majority of the filamentous fungi and influence spore properties (for reviews, see [ 26 – 29 ]). Thus, we hypothesized that the respective genes could be suitable targets for ecological genetic investigation.…”

Exploring malted barley waste for fungi producing surface active proteins like hydrophobins

“…Study suggested that deletion of hydrophobin genes from fungal species lead to minimal foaming during fermentation process. Genes of HFBI and HFBII deleted from T. reesei resulted in developing less foam during fermentation process due to absence of these proteins in fermentation broth in comparison to wild type strain [44].…”