Microorganisms associated with upper soil and decaying biomass are comprised of a rel­atively small group of microorganisms that can be grown in vitro and a larger majority that cannot be grown. The most extensive zone of microbial growth occurs on surfaces of biomass, usually within the rhizosphere region of soil. The most studied biomass degrad­ing microbial communities are those involved composting, wet wood, estuaries, and forest floor (60-63). Historically, the ecology of these sites has been investigated by examining those organisms that could be isolated and grown in the laboratory or by measuring the enzymes they produce. Most reports describing the population dynamics have been done by traditional culture and phenotyping methods (64), through the use of systems such as the BIOLOG method (65, 66), by the measurement of phospholipid fatty acid patterns in soil or litter samples (67, 68), and by extracting and monitoring enzyme activities (69). It has also been reported that augmentation of a biomass with specific enzymes, primarily cellulases, stimulates decomposition (70), although the mechanisms at the community or molecular level are not known.