HYPHAL SHEATH AND IRON-BINDING COMPOUND FORMATION IN LIQUID CULTURES OF WOOD DECAY FUNGI GLOEOPHYLLUM-TRABEUM AND POSTIA-PLACENTA

Hyphal sheath (extracellular matrix) and iron-binding compound formati on in liquid cultures of the brown rot fungi Gleophyllum trabeum and P ostia placenta were examined as a function of incubation temperatures, culture pH, and concentrations of iron, manganese, and nitrogen in th e culture medium. Hyphal sheath was observed microscopically and quant ified with Jandel video analysis (JAVA). The hyphal sheath was found o n young and rejuvenated hyphal around the hyphal rips and along the le ngth of the hyphae, but not on necrotic hyphae Production of hyphal sh eath was greater in fungi growing in low concentrations of metals (0-5 0 mu M iron or 0-100 mu M manganese) than in fungi growing under high metal concentrations-High nitrogen concentrations decreased sheath for mation in G. trabeum. Iron-binding compound formation, as monitored by the chrome azurol S (GAS) assay, did not occur in detectable quantiti es until the third week of culture incubation Iron-binding compound pr oduction was correlated with low concentrations of metals, but was not significantly influenced by the form of the nitrogen source. High lev els of manganese (1000-5000 mu M) and iron (150-200 mu M) repressed bo th iron-binding compound production and hyphal sheath formation Incuba tion temperature and pH of the medium influenced hyphal sheath and iro n-binding compound formation by both brown rot fungi. Gloeophyllum tra beum produced more hyphal sheath and iron-complexing agents at pH 3.5, 35 degrees C than under other cultural conditions tested. Postia plac enta yielded more Sheath at pH 5.5, 25 degrees C than under other cult ural conditions tested. Both fungi decreased the culture pH over time, irrespective of starting pH, to a final pH of 2.4 to 3.0. Greatest de creases in PH values were seen in cultures low in manganese and iron. The influence of transition metal concentration and other experimental parameters on PH, ratio of hyphal sheath to hyphal area, and oil the production of extracellular high affinity iron-binding of the role the se parameters have been shown to play in the compounds is of significa nce because biodegradation of wood by brown rot fungi.