Latest news from Trichoderma/Hypocrea world.
Dear ISTH users,
now we release the new tool Tricho CHIT - an oligonucleotide DNA BarCode for directed screening for superior chitinase producers among H. lixii/T. harzianum strains.
Application of DNA BarCodes for screening of industrially important fungi: the haplotype of Trichoderma harzianum sensu stricto indicates superior chitinase formationSelection of suitable strains for biotechnological purposes is frequently a random process supported by high-throughput methods. Using chitinase production by Hypocrea lixii/Trichoderma harzianum as a model, we tested, whether fungal strains with superior enzyme formation may be diagnosed by DNA BarCodes. We analysed sequences of two phylogenetic marker loci i.e. the internal transcribed spacers 1 and 2 (ITS1 and 2) of the rRNA-encoding gene cluster and the large intron of elongation factor 1-alpha, tef1 , from 48 isolates of H. lixii/T. harzianum, which were also tested for their ability to produce chitinases in solid state fermentation (SSF). A statistically supported superior chitinase production was obtained for strains carrying one of the observed ITS1 and 2 and tef1 alleles corresponding to T. harzianum type strain CBS 226.95. A tef1 based DNA BarCode tool Tricho CHIT for rapid identification of these strains was developed. The geographic origin of the strains was irrelevant for chitinase production. The improved chitinase production by strains containing this haplotype was not due to better growth on n- acetyl-ß-d-glucosamine or glucosamine. Isoenzyme electrophoresis showed that neither the isoenzyme profile of n- acetyl-ß-glucosaminidases or of the endochitinases, nor the intensity of staining of individual chitinase bands correlated with total chitinase in the culture filtrate. The superior chitinase producers did not exhibit similarly increased cellulase formation. Biolog Phenotype MicroArray analysis identified the lack of n- acetyl-ß-d-mannosamine utilization as a specific trait of strains with the chitinase overproducing haplotype. This observation was used to develop a plate screening assay for rapid microbiological identification of these strains. The data illustrate that desired industrial properties may be an attribute of certain populations within a species, and screening procedures should thus ensure to include a balanced mixture of all genotypes of a given species.
Nagy et al., 2007, Applied and Environmental Microbiology, ms in press
Irina Druzhinina & Alexey Kopchinskiy