O2 requirements for growth and survival of wood-decaying and sapwood-staining fungi

Various experiments were conducted to examine O2 requirements 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 O2 deficiencies than those that attack better-aerated wood (product rotters). Growth of cultures exposed to flowing mixtures of O2 and N2 was moderately retarded by an O2 pressure of about 11 mm (1 mmHg = 133.322 Pa) and was severely retarded by a pressure near 2 mm. None of the fungi grew with 1.5 mm of O2. Comparable minimal O2 pressures 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 O2 pressure. 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 surv...