Dioscorea alata as Alternative Culture Media for Fungal Cultivation and Biomass Production

Abstract

Dioscorea alata (purple yam) is a tuber crop that contains plenty of nutrients. It is widely cultivated in Thailand, but it is underutilized. In this study, the suitability of purple yam to replace potato dextrose media for fungal growth was investigated. Mushrooms and molds were grown on purple yam dextrose agar (PYDA), whereas yeasts were cultured in purple yam dextrose broth (PYDB). Response surface methodology (RSM) with Box-Behnken design (BBD) was used to optimize the culture conditions for Saccharomyces cerevisiae biomass production. The growth profile of S. cerevisiae in PYDB under optimized culture conditions was also studied. All test mushrooms and molds recorded the highest colony diameter and mycelial dry weight on PYDA containing 40% purple yam. Similar to mushrooms and molds, yeasts in PYDB with 40% purple yam showed the highest number of cells. The growth of fungi on purple yam dextrose media was significantly higher than those on potato dextrose media under standard conditions. The optimal conditions from the RSM results for the biomass production of S. cerevisiae in PYDB were purple yam concentration of 49.61%, dextrose concentration of 4.87%, pH value of 5.74, and inoculum size of 7.00%. The biomass of S. cerevisiae in PYDB under the optimal conditions obtained from the results of the optimization by RSM was thirty times higher than S. cerevisiae biomass in potato dextrose broth under standard conditions. Our results suggest that purple yam could be an alternative to potato dextrose media for fungal cultivation.