Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 8. (Budapest 1957)
Bohus, G. ; Gyarmati, B.: The effects of temperature and pressure on fungi causing wood-decay
Of the numerous fungus species infecting Sortiments of various wooden materials for various purposes, we have selected the following ones : Bispora monilioides Bulgaria polymorplia Coniofjhora cerebella Daedalea que rein a Hypoxylon coccineuni Lentinus squamosus Lenzites abietina Lenzites betulina Meruit us lacrymans Poria vaporaria Schizophyllum commune Stereum purpureum Trameies liirsuta Trametes versicolor Vertici/lium glaucum The species were selected with consideration to include, as far as possibilities permitted, species characteristical of several important woods, and of various infecting, that is, decay causing grade. Methods Pure cultures of the species selected were raised on malt extract agar, an excellent medium for these species. Test tube cultures were exposed to the corresponding heat effect in a fivefold, in the case of certain species, in a tenfold repetition. It did not seem advisable 1o choose a period shorter that an hour as the lowest time limit for the heat treatment, since in the case of such short duration one cannot disregard the time required for the cultures to warm up to the degree of heat wanted. Even after a 48 hours heat treatment, we were unable to observe a slight desiccation of the culture media, so the heat treatment was effectual in a humid setting even for aerial mycelia. The treated cultures were inoculated on malt extract agar, and incubated at 24° C; in the case of Merulius lacrymans, at 20° C. Results The application of heat treatments Processes to saturate the various Sortiments (the Bethel ; the simple and double Riipping processes) are based on variations of the applications of vacuum and saturant pressures, while the temperature of the saturant varies between 100—70° C during the time of the pressing. The duration of the heat effect is (in the case of the most infection-inclined beech sleepers, inclusive of the intermediate working processes) 4 hours at the very best. During this time, the middle of standard-sized samples warms up, according to both theoretical computations and actual readings, as follows : After 1 hour 37° C After 3 hours 58° C After 2 hours 50° C After 4 hours 65° C (if the temperature of the wooden material was 18° C, and the temperature of the saturant was kept at 100° C. This condition cannot generally be complied with in reality). If the duration of the cooling off is also taken into consideration, the following temperatures can be relied upon in the middle of the sample and in a favourable case: above 40° C about 6 hours; above 50° C about 4 hours; above 60° C about 2 hours. The heat toleration of the selected fungi species were therefore studied chiefly between these limits. We found the following results :
