EXTRACTION OF BITUMENS AND HUMIC SUBSTANCES FROM PEAT AND THEIR EFFECTS ON THE GROWTH OF AN ACID-TOLERANT FUNGUS

Acid hydrolysates of peat, from which the bitumens or humic substances have been removed ("modified peats"), were employed as substrates for the growth of the acid-resistant fungus Scytalidium acidophilum (Sigler and Carmichael). The removal of either or both of these fractions from the peat produced a lower dry biomass concentration than that obtained when S. acidophilum was grown in the hydrolysates of the whole peat, even when supplemented with additional nutrients. Two fractions of the humic substances, humic and fulvic acids, were extracted from peat and incorporated into synthetic media. The humic acid fraction, up to a concentration of 0.2% at pH 2.0 and 0.37% at pH 8.0, enhanced the fungal growth, but the fulvic acid fraction inhibited it at all the concentrations tested. © 1990.