Investigations into the 'in vitro-liquefaction' of brown coal

摘要

Brown coal can be liquefied/solubilized by a number of lignin-degrading fungi. However, with regard to technical applications in the future, the use of whole fungal cells is severely limited due to the mechanical and chemical sensitivity of the hyphae, and the expensive nutrition of the living cells. Therefore many attempts have been made to make use of the coal-degrading enzymes produced by the fungus, mainly lignin peroxidases, manganese dependent peroxidases, and laccases. As it turned out, however, the isolated enzymes could not lower the mean molecular weight of the coal substances, but led to polymerization reactions due to the formation of reactive radical species. Apparently the living cell is able to prevent excessive levels of radical concentrations by the means of sensitive regulating mechanisms.