Researchers Evaluate Ethanol Production from Mushroom Compost from Chaff of Millet and Sorghum

In Uganda, the chaff left from threshed panicles of millet and sorghum is a low value, lignocellulose-rich agricultural by-product. Currently, it is used as a medium for growing edible Oyster mushrooms (Pleurotus ostreatus). Peter Ryden of the Quadram Institute of Bioscience in the UK, assessed the potential of the residual post-harvest compost as feedstock for producing ethanol.

Sorghum and millet chaff derived from spent oyster mushroom composts were assessed at small-scale and low substrate concentrations for ethanol production. Millet-based compost had low cellulose content and did not liquefy effectively. The ethanol yield was 63.9 g/kg dry matter of original material.

On the other hand, compost from sorghum chaff had higher cellulose content and could be liquefied at high substrate concentration. This enabled yeasts to produce more ethanol at up to 186.9 g/kg dry matter of original material.

Spent mushroom compost derived from sorghum chaff has the potential to be an industrial substrate for producing bioethanol. However, compost from millet does not provide a high concentration of ethanol to make it industrially attractive.