Some nutritional and environmental factors affecting growth and production of sclerotia by a strain of Aspergillus niger

Abstract

The effects of two nutritional elements (carbon and sulfur) and two environmental factors (pH and temperature) on growth and sclerotial production of Aspergillus niger were determined on a synthetic agar medium. The fungus grew and produced sclerotia under laboratory conditions on media containing wide ranges of carbon and sulfur sources. Of the 20 carbohydrates tested, only ribose, mannitol, and malonic, fumaric, and citric acids failed to induce production of sclerotia. A synergistic effect was observed on the formation of sclerotia when favorable and unfavorable carbon sources were supplied in different combinations. Of the 14 sulfur compounds tested, magnesium sulfate yielded the highest and sodium sulfite the lowest number of sclerotia. Raising the concentration of magnesium sulfate to 3 g/l increased the number of sclerotium initials and the number and dry weight of those which matured. In general, no correlation occurred between the number of sclerotia formed and their dry weights on different carbon or sulfur sources. Sclerotia were most numerous at pH 7.0 and 35 °C.