Browsing by Author "Munoz, G"

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    Differential expression of the vegetative and spore-bound hydrophobins of Trichoderma reesei - Cloning and characterization of the hfb2 gene
    (1997) NakariSetala, T; Aro, N; Ilmen, M; Munoz, G; Kalkkinen, N; Penttila, M
    The hfb2 gene encoding the hydrophobin HFBII of the filamentous fungus Trichoderma reesei was isolated by heterologous hybridization using the vegetative hydrophobin I, hfb1, gene of T. reesei as a probe. The hfb2 gene codes for a typical fungal secreted hydrophobin of 71 amino acids containing eight cysteine residues. The amino acid similarity towards HFBI is 69%. The HFBII protein was isolated from the fungal spores by extraction with trifluoroacetic acid/acetonitrile solution, and by bubbling from the lactose-based culture medium. Expression of the hfb1 and hfb2 genes is divergent, hfb1 expression was only observed in vegetative cultures on glucose-containing and sorbitol-containing media. It was not expressed on media containing complex plant polysaccharides, cellulose, xylan, cellobiose or lactose, whereas hfb2 was highly expressed in vegetative cultures on these media. Expression of hfb2 was also strongly induced by N and C starvation, by light and in conidiating cultures.
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    Effect of culture conditions on spore shelf life of the biocontrol agent Trichoderma harzianum
    (1997) Agosin, E; Volpe, D; Munoz, G; SanMartin, R; Crawford, A
    The influence of pH, carbon:nitrogen (C:N) ratio, carbon content and harvesting time on spore attributes of the biocontrol agent Trichoderma harzianum was evaluated. The effect of these culture parameters on viability, shelf-life and ultrastucture was also assessed. pH was a key parameter to manipulate for both growth and sporulation, while carbon concentration and C:N ratio strongly affected spore production time. At fixed pH, the C:N ratio had a limited influence on production yield, but was critical for spore shelf-life. The highest spore longevity was found in a medium with a C:N ratio of 14 and a pH of 7.0, when most resulting spores were still alive after 45 d storage. These spores also remained viable during storage under a broad range of relative humidities, indicating that they would be more sustainable in the field.
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    Hydrophobin gene srh1, expressed during sporulation of the biocontrol agent Trichoderma harzianum
    (1997) Munoz, G; NakariSetala, T; Agosin, E; Penttila, M
    A cDNA clone encoding a spore-related hydrophobin, SRHI, was isolated from a cDNA bank prepared from mRNA induced in sporulating cultures of Trichoderma harzianum by heterologous hybridization using the hfb2 gene encoding a spore-bound hydrophobin of Trichoderma reesei as a probe. Based on sequence similarity the predicted protein was identified as a new member of the class-II hydrophobin family. Including the signal sequences, SRHI has 65% and 56% amino-acid similarity with the T. reesei hydrophobins HFBII and HFBI, respectively, being less similar with other hydrophobins. srh1 is present as one copy in the T. harzianum genome. It is highly expressed under sporulating conditions, both in submerged as well as in aerial cultures. Moreover, nutrient limitation induces srh1 expression.