Influence of cultural conditions on coal solubilization by Penicillium simplicissimum

Sub‐bituminous coal, preoxidized with nitric acid and treated with sodium hydroxide solutions to obtain a water‐soluble extract, was used for the study of coal degradation by Penicillium simplicissimum. The influence of different carbon and nitrogen sources was examined in connection with growth and production of acid‐precipitable coal polymers. The yield was increased after the addition of maltose, lactose and cellobiose while glucose, fructose and xylose had little effect. An organic nitrogen source, yeast extract, was an improved source of nitrogen compared with ammonium chloride. The coal‐degrading system appeared before the depletion of the carbon or nitrogen source. In addition, the effects of initial pH of the culture medium demonstrated an increase in the yield of coal polymers up to a pH of 7.5. Above this pH, non‐biological catalysis increased gradually. However Ca2+ and Mn2+ increased the yield of coal polymers over a 14‐day period, but yield was unaffected by Cu2+, Al3+ and Fe2+.