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Enzymatic study of Ceratocystis sp., blue-stain fungi on Pinus nigra
1999 - IRG/WP 99-10315
One of the main problems that the forest exploitation industry has with Pinus nigra wood is the blue-stain fungi, whose causing agent is unknown. Therefore, the objective of this work has been to study, through enzymatic tests of the isolated cultures, if these fungi infect Pinus nigra in any specific way. After the incubations, isolates of Ceratocystis were obtained. These were cultured in a saline medium with sawdust of Pinus nigra and Pinus sylvestris, which were used as reference species. At different incubation times, carboxymethylcellulase, xylanase, cellobiohydrolase, laccase and manganese peroxidase were determinated. The results obtained show that the cellulolytic enzymes and laccase have higher activity on Pinus nigra sawdust than on Scots pine, while the Mn peroxidase showed higher values on the sawdust of the latter. Likewise, the cultures were developed in the same saline base medium with different monosacarides (glucose, galactose, mannose, xylose and arabinose), and in determining the residual sugar content, a marked prefrence for the consumption of pentoses in respect to the glucose was observed. The enzymatic activity tests carried out by APY ZYM also showed qualitative and semiquantitative differences between the isolated fungi and other Ceratocystis species tested, so, in addition to the above results, this could indicate a certain specificity of these fungi for this wood species.
M T De Troya, F Rubio, D Muñoz-Mingarro, F Llinares, C Rodríguez-Borrajo, M Yuste, M J Pozuelo, J I Fernández-Golfín
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