Studies on the growth of fungus Scytalidium acidophilum in hydrolysates from sphagnum peat moss

Abstract

Scytalidium acidophilum was cultured in various peat based substrates to determine which one would produce the highest concentration of biomass. Peat was hydrolyzed individually with sulfuric, hydrochloric, nitric and phosphoric acids and the hydrolysates used as substrates to prepay the media for culturing the fungus. The proximate composition of the hydrolysates were determined. The H₂SO₄- hydrolysate of peat was the richest in carbohydrate concentration. The constituent monosaccharides in the peat hydrolysates were determined by High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC). Hexoses constituted more than 50 % of the total reducing sugars present in the peat hydrolysates. -- Preliminary experiments with synthetic media showed that a 5 % (v/v) inoculum ratio produces the highest growth of the fungus. Growth of the fungus on the media containing different carbon sources indicated that hexoses were better utilized by the fungus than pentoses. -- Undiluted and water-diluted peat hydrolysates were used for culturing the fungus. Peat hydrolyzed with sulfuric acid and diluted 1:1 with water produced the highest growth parameters of the fungus. Supplementation of the hydrolysates with 3 g/L yeast extract and 0.4 g/L magnesium sulfate improved the growth of the fungus compared to the other nutritional additives tested. -- The effects of components of peat on the growth of the fungus were investi-gated. A study involving the removal of one peat component (modified peats) to avoid the potential inhibitory effect of peat is not a viable method of increasing the biomass production. A comparison of non-modified and modified peat hydrolysates showed that modification of peat results in a loss of nutrients. -- The nutrient supplementation of modified peat hydrolysates caused no statistically significant increases (P < 0.05) in the growth parameters as compared with those obtained when non-supplemented modified peat hydrolysates were used. -- Fractionation of humic substances of peat was completed to identify the growth inhibiting components. The fulvic acid fraction was found to show inhibitory effect on the growth of the fungus while the humic acids fraction was stimulatory. -- Hydrolysates obtained from peat-fish offal compost were also used as sub-strates for the growth of the fungus. Growth curves have been constructed by growing S. acidophilum in peat and compost hydrolysates. The composition of biomass produced on peat hydrolysate was determined.