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In this study the wood anatomical description of 12 species characteristics from cloud forest in the State of México was carried out. For each species the qualitative and quantitative microscopic characters of wood are described. On the basis of the Runkel relationship, the quality of their fibers is classified to obtain pulp for paper. The morphological characteristics of each species are given, as well as their common names and national distribution. Eight species have growth rings formed by bands of fibers with lumens reduced and thick walls, or compressed radially, in the late wood. The porosity is diffuse; the vessels are small, with less than 100 µm diameter, and numerous. Several species presented vessel elements with scalariform perforation plates Vessel elements and fibers were medium and long. In general the axial parenchyma is scarce and in seven species the rays are heterogeneous type I. These results are similar to those obtained in other regions. According to the relationship of Runkel it was found out that the fibers are of medium to good quality for paper. [ABSTRACT FROM AUTHOR]

Durango, Mexico pine woods have higher resin content than those from southern US. For this reason, a biotechnological study to remove resinic acids and other pitch precursors in pine chips was performed to improve the production of a mechanical pulp mill. Forty nine native strains were isolated and some of them identified as Paecilomyces sp., Penicillum sp., Phialophora sp., Trichosporon sp., Rhodotorula sp., Cryptococcus sp. and Chryseomonas luteola. The later one was the most active in degrading resin components in the flask (87,3 %) and tested in preliminary heap leaching fermentation assays. Paecilomyces sp. was the second most effective (86,6 %) and tested in semisolid fermentation trials. Both solid phase fermentation processes afforded far lower yields compared to the flask experiments. INSETS: KEY WORDS;Degradación de pitch por los microorganismos seleccionados;Cepas aisladas en cada tratamiento cuya fuente de carbono...;Identificación de bacterias aisladas según la tinci [ABSTRACT FROM AUTHOR]