Various experiments were conducted to examine O2requirements for growth and survival of a total of 48 wood-destroying basidiomycetes and 6 sapwood-staining fungi. An additional objective was to determine whether species that invade heartwood of living trees (heartrotters) are more tolerant of O2deficiencies than those that attack better-aerated wood (product rotters). Growth of cultures exposed to flowing mixtures of O2and N2was moderately retarded by an O2pressure of about 11 mm (1ensp;mmHgensp;=ensp;133.322 Pa) and was severely retarded by a pressure near 2ensp;mm. None of the fungi grew with 1.5ensp;mm of O2. Comparable minimal O2pressures for growth were found by growing the fungi in a closed chamber (with an attached manometer) containing NaOH to absorb CO2, then regularly measuring growth and internal O2pressure. Fungi grown in a closed chamber consumed all of the available O2. Length of survival of species grown in sealed test tubes differed markedly, from less than 1 week to more than 2 years. The species surviving longest included more heartrotters than product rotters.
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