SCREENING OF FUNGI FOR THE BIOLOGICAL MODIFICATION OF HARD COAL AND COAL DERIVATIVES

A biotechnological depolymerization of hard coal is being attempted with basidiomycetous fungi native to timber, plant residues, and soil, and with microfungi of lignite sources and contaminated soil. The coal materials such as powdered or hydrogenated hard coal (asphaltene) were aseptically exposed to fungal pure cultures in a four-step screening system. Agar surface cultures were examined for softening and erosion of the coal particles, and for alterations in the asphaltene films fixed to plastic chips and silica gel. From the shake cultures, both the culture fluid and the coal or asphaltene sediments were separately collected and processed by photospectrometry, gel permeation chromatography, combined gas chromatography-mass spectrometry, and IR spectrometry. Of the 243 fungal strains tested to date, four were reactive on coal materials and asphaltene. Two basidiomycetes (Coriolus hirsutus [Wulf.] Quel.; Coprinus sclerotiger Wart.) eroded hard coal particles, while another basidiomycetous strain (Agrocybe semiorbicularis [Bull.:Fr.]) separated the asphaltene him from its plastic carrier. The hyphomycete Trichoderma spec. strain AB2 caused alterations in the IR spectrum of asphaltene.