%0 Journal Article %A Kruszewska, Joanna %A Palamarczyk, Grazyna %A Kubicek, Christian P. %T Stimulation of exoprotein secretion by choline and Tween 80 in Trichoderma reesei QM 9414 correlates with increased activities of dolichol phosphate mannose synthase %D 1990 %J Microbiology, %V 136 %N 7 %P 1293-1298 %@ 1465-2080 %R https://doi.org/10.1099/00221287-136-7-1293 %I Microbiology Society, %X Addition of choline (20 mm) or Tween 80 (0ยท06%) to the culture medium of Trichoderma reesei QM 9414 increased (a) the secretion of protein under both carbon-catabolite-repressed and -derepressed conditions, and (b) cellulase secretion under carbon-catabolite-derepressed conditions. In contrast, no stimulation by choline or Tween 80 was observed with the hypersecretory strain T. reesei RUT C-30. In view of the obligatory role of O-glycosylation in protein secretion by this fungus, an investigation was made into the effects on this process of choline and Tween 80. A membrane preparation was isolated from both strains of T. reesei and used to assay enzymes involved in O-glycosylation. Significant differences were observed with respect to the activity of dolichol phosphate mannose (Dol-P-Man) synthase only. Strain QM 9414, grown on media supplemented with choline or Tween 80 exhibited a two- to threefold higher activity of Dol-P-Man synthase compared to a control lacking these supplements. This stimulatory effect was observed during growth under both carbon-catabolite-repressed and -derepressed conditions. In contrast, strain RUT C-30 exhibited decreased activities of Dol-P-Man synthase when grown in media supplemented with choline. Choline had no effect on Dol-P-Man synthase in vitro, whereas Tween 80 decreased the activity. Thus the effect of Tween 80 or choline on protein secretion by T. reesei may be due to a stimulation of formation and/or activity of Dol-P-Man synthase, thereby elevating the level of O-glycosylation and protein secretion. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-136-7-1293