Trichoderma longibrachiatum

Abstract: Osmotin protein is able to inhibit in vitro the growth of a number of unrelated pathogens. A survey of 31 isolates representing 18 fungal genera indicated that sensitivity may be determined at the genus level. Hyphal growth of Aspergillus flavus, Aspergillus parasitica, Rhizoctonia solani and Macrophomina phaseolina was highly resistant to osmotin whereas the growth of Bipolaris, Fusarium and Phytophthora species was very sensitive. Of all fungi tested Trichoderma longibrachiatum hyphal growth was most inhibited by osmotin treatment. Osmotin either induced spore lysis, inhibited spore germination or reduced germling viability in seven fungal species that exhibited some degree of sensitivity in hyphal growth inhibition tests. The species-specific growth inhibition was correlated with the ability of osmotin to dissipate the fungal membrane pH gradient. Both growth inhibition and pH gradient dissipation by osmotin were sensitive to NaCl and other inorganic cations. Cells of T. longibrachiatum were insensitive to osmotin after plasmolysis, suggesting that the cell wall may be a component of the mechanism by which osmotin permeabilizes the plasma membrane and kills fungal cells.

Abstract: The relationship of the important cellulase producing asexual fungus Trichoderma reesei to its putative teleomorphic (sexual) ancestor Hypocrea jecorina and other species of the Trichoderma sect. Longibrachiatum was studied by PCR-fingerprinting and sequence analyses of the nuclear ribosomal DNA region containing the internal transcribed spacers (ITS-1 and ITS-2) and the 5.8S rRNA gene. The differences in the corresponding ITS sequences allowed a grouping of anamorphic (asexual) species of Trichoderma sect. Longibrachiatum into Trichoderma longibrachiatum, Trichoderma pseudokoningii, and Trichoderma reesei. The sexual species Hypocrea schweinitzii and H. jecorina were also clearly separated from each other. H. jecorina and T. reesei exhibited identical sequences, suggesting close relatedness or even species identity. Intraspecific and interspecific variation in the PCR-fingerprinting patterns supported the differentiation of species based on ITS sequences, the grouping of the strains, and the assignment of these strains to individual species. The variations between T. reesei and H. jecorina were at the same order of magnitude as found between all strains of H. jecorina, but much lower than the observed interspecific variations. Identical ITS sequences and the high similarity of PCR-fingerprinting patterns indicate a very close relationship between T. reesei and H. jecorina, whereas differences of the ITS sequences and the PCR-fingerprinting patterns show a clear phylogenetic distance between T. reesei/H. jecorina and T. longibrachiatum. T. reesei is considered to be an asexual, clonal line derived from a population of the tropical ascomycete H. jecorina.

Abstract: As a first step to exploit the potential of Trichoderma reesei to produce hemicellulases, we have purified two endo-β-1,4-xylanases (1,4-β-D-xylan xylanohydrolase, EC 3.2.1.8) and cloned their genes. The enzymes were isolated from culture filtrates of T. reesei C 30 grown on xylan as a carbon source, using two steps of cation exchange chromatography. They exhibited molecular weights of 19 (XYN I) and 21 (XYN II) kD, and isoelectric points of 5.2 and 9.0, respectively. These enzymes differed in their pH optimum for activity and affinity for xylan, and accounted for more than 90% of the total xylanolytic activity of the fungus. The purified enzymes were subjected to N-terminal sequence analysis, and after cleavage with trypsin and endoproteinase Glu-C the resulting peptides were sequenced. Oligonucleotides based on these sequences were used to clone gene fragments via PCR, and these were used as probes to isolate full-length copies of xyn1 and xyn2 from a lambda gene bank of T. reesei. The products of xyn1 and xyn2 share considerable homology, but the enzyme encoded by xyn2 appears to more closely resemble several other bacterial and fungal xylanases than does that of xyn1.

Abstract: Variation in strains assignable to the Trichoderma longibrachiatum Rifai and T. pseudokoningii Rifai species aggregates was studied. Morphological similarities allow their assignment to one section...

Abstract: A cDNA expression library of Trichoderma reesei RutC-30 was constructed in the yeast Saccharomyces cerevisiae Two genes, abf1 and bxl1, were isolated by screening the yeast library for extracellular alpha-L-arabinofuranosidase activity with the substrate p-nitrophenyl-alpha-L-arabinofuranoside The genes abf1 and bxl1 encode 500 and 758 amino acids, respectively, including the signal sequences The deduced amino acid sequence of ABFI displays high-level similarity to the alpha-L-arabinofuranosidase B of Aspergillus niger, and the two can form a new family of glycosyl hydrolases The deduced amino acid sequence of BXLI shows similarities to the beta-glucosidases grouped in family 3 The yeast-produced enzymes were tested for enzymatic activities against different substrates ABFI released L-arabinose from p-nitrophenyl-alpha-L-arabinofuranoside and arabinoxylans and showed some beta-xylosidase activity toward p-nitrophenyl-beta-D-xylopyranoside BXLI did not release L-arabinose from arabinoxylan It showed alpha-L-arabinofuranosidase, alpha-L-arabinopyranosidase, and beta-xylosidase activities against p-nitrophenyl-alpha-L-arabinofuranosidase, p-nitrophenyl-alpha-L-arabinopyranoside, and p-nitrophenyl-beta-D- xylopyranoside, respectively, with the last activity being the highest It was also able to hydrolyze xylobiose and slowly release xylose from polymeric xylan ABFI and BXLI correspond to a previously purified alpha-L-arabinofuranosidase and a beta-xylosidase from T reesei, respectively, as confirmed by partial amino acid sequencing of the Trichoderma-produced enzymes Both enzymes produced in yeasts displayed hydrolytic properties similar to those of the corresponding enzymes purified from T reesei