SCANNING ELECTRON-MICROSCOPY OF THE MICROBIAL COLONIZATION OF COMPOSTED TREE BARK

Scanning electron microscopy has been used to study the ecology of the microbial communities responsible for the decomposition of sitka spru ce bark composted at 40-degrees and 50-degrees-C. Bark particles at bo th temperatures were covered by a smooth amorphous film of short bacte rial rods. Fungal spores, but few hyphae were visible above this film. At 40-degrees the pre-dominant fungus was Aspergillus fumigatus, a po tential human pathogen, but at 50-degrees, Rhizomucor, Geosmithia and Thermoascus spp. were more common. New information on the role of ther mophilic yeasts was discovered as they were found to colonise the disr upted cleistothecia of a Thermoascus sp. as well as colonising the sur face of the bark.