Rhizopus oligosporus was cultivated on thin stillage from a dry-grind corn ethanol plant. The aim of the
research was to develop a process to replace the current energy-intensive flash evaporation and make
use of this nutrient-rich stream to create a new co-product in the form of protein-rich biomass. Batch
experiments in 5- and 50-L stirred bioreactors showed prolific fungal growth under non-sterile conditions.
COD, suspended solids, glycerol, and organic acids removals, critical for in-plant water reuse,
reached ca. 80%, 98%, 100% and 100%, respectively, within 5 d of fungal inoculation, enabling effluent
recycle as process water. R. oligosporus contains 2% lysine, good levels of other essential amino acids,
and 43% crude protein – a highly nutritious livestock feed. Avoiding water evaporation from thin stillage
would furthermore save substantial energy inputs on corn ethanol plants