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Detection of semi-quantitative and qualitative enzymatic activities of blue-stain fungi
2000 - IRG/WP 00-10347
Blue-stain, produced in forests, continues to be a problem in countries of moderate climate. In forestry, in certain geographical areas of Spain, it has been observed that anti-sapstain products have not always been efficient, as their fungicidal effectiveness varies on occasion, depending on the species of wood and microbiota that exist in the region. It is not always easy to identify the species causing this damage. Therefore, the object of this study was the grouping of diverse isolates according to the detection of simple enzymatic activities, following a simple and rapid method of application such as API-ZYM. 36 strains of Ceratocystis spp, isolated from divers species of Pinus spp., have been tested. The results were contrasted with the activities detected in the same conditions in Pullularia pullulans and Sclerophoma pityophila. To do this, these strains were inoculated in culture broths with a basic saline Eggins and Pugh medium, to which 1% sawdust of Pinus sylvestris was added in one trial. Another test was made with a mixture of the most frequent monosaccharides in woody cell-walls (glucose, mannose, galactose, arabinose, and xylose) at 1%. After 20 days of incubation, the extracts were centrifuged, and inoculated in microtubes series of API-ZYM. The analysis of the principal components, carried out with the results obtained, showed that the sawdust induces enzymatic activities implicated in the degradation of polysaccharides such as in a-mannosidase, a-galactosidase, b-glucuronidase, b-glucosidase and b-galactosidase, which appeared as the most weighty specific factors in the dispersion of data on the first two principal axes. Different strains of Ceratocystis also showed similar or greater activity than those of P. pullulans and S. pityophila, which suggests that the latter might be more virulent than the rest of the strains assayed.
M T De Troya, F Llinares, D Muñoz-Mingarro, M J Pozuelo, N Acero, C Rodríguez-Borrajo, A M Navarrete


The effect of tunicamycin on production and secretion of extracellular carbohydrate-degrading enzymes by Postia placenta
1988 - IRG/WP 1342
The extracellular carbohydrate-degrading enzymes of wood-decay fungi are usually heavily glycosylated and therefore stable under most denaturing conditions. It is unlikely that wood decay can be prevented by simply inactivating these enzymes. Tunicamycin, an antibiotic produced by Streptomyces lysosuperificus, prevents the glycosylation of glycoproteins and can interfere with the secretion of these enzymes. The effect of tunicamycin on the production of extracellular carbohydrate-degrading enzymes of Postia placenta was determined in liquid culture. Enzyme production was inhibited at concentrations of 2.5-5 mg/ml; glycosidases were more sensitive than glycanases. Colony morphology was greatly altered at these concentrations, but dry weights decreased only 20-30%. The thermostabilities of xylanase and a-galactosidase, and the pH stability of xylanase, decreased when formed in the presence of low concentrations of tunicamycin. This suggests that the enzymes are produced in an active but nonglycosylated (or underglycosylated) form. The deglycosylation of glycoproteins may be a physiologically specific means of controlling wood-decay fungi.
J A Micales, T L Highley


The effect of Tween 80 on the growth, morphology, and enzyme secretion of Postia placenta
1990 - IRG/WP 1456
The nonionic surfactant Tween 80 (polyethylene oxide sorbitan mono-oleate) has been reported to increase enzyme production and/or secretion in bacteria and fungi. Such a procedure could greatly facilitate research into the physiology of wood-decay fungi since quantities of available enzyme are often limiting. The brown-rot fungus Postia placenta was grown in a synthetic medium supplemented with 0, 0.01, 0.05, 0.1, 0.2, and 0.4% Tween 80. The addition of even the lowest percentage of Tween significantly increased mycelial dry weight and prevented the formation of aerial hyphae. With the exceptions of ß-D-glucosidase and ß-D-galactosidase, extracellular carbohydrate-degrading enzyme production did not change. Levels of xylanase, carboxymethylcellulase, laminarinase, and ß-D-galactosidase remained unaffected by the presence of Tween. Some factor other than secretion mechanisms, such as microelement or nitrogen availability, is probably limiting production of these enzymes.
J A Micales