ABSTRACT
Direct formation and recovery of a water-soluble product from microbial action on solid coal was first reported by Cohen and Gabriele. Coal biosolubilization has become a subject of increasing interest as a possible approach to the utilization of low-rank coals. This chapter presents the results of analytical chemistry and biochemistry experiments that have been applied to the characterization of biosolubilized products and enzymatic systems studied in our laboratories. Coal rank is an important factor in determining the extent and rate of microbial solubilization. Experiments in several laboratories indicate that low-rank coals, such as leonardite and lignite, are more amenable to biosolubilization than are the higher-rank subbituminous and bituminous coals. The process of solubilization was evident within 24 h and continued with the amount of bioextract increasing over several days until many of the coal pieces were completely liquefied. The bioextract was generally harvested from the fungal cultures after 5 days, freeze-dried, and stored desiccated at room temperature.
