Abstract
The discovery in 1982 that microorganisms can interact with, and presumably modify, the chemical structure of coal has focused attention on the potential for the use of microbial cultures or isolated microbial enzymes in coal conversion. Biological processes based on this activity will promote the effective utilization of lowrank coal, which is poorly suited to direct combustion. Research in this area may also support the development of improved biological technologies for the cleaning of highrank coal and/or the treatment of coalderived waste.