Production of protein-rich fungal biomass in an airlift bioreactor using vinasse as substrate

The potential for large-scale production of an edible fungus, Rhizopus oligosporus, on a liquid residue from sugar-to-ethanol production, vinasse, was investigated. An airlift bioreactor (2.5-L working volume) was used for cultivating the fungus on 75% (v/v) vinasse with nutrient supplementation (nitrogen and phosphorus) at 37 degrees C and pH 5.0. Aeration rates were varied from 0.5, 1.0, 1.5 to 2.0 volume(air)/volume(liquid)/min (vvm). The fungal biomass yield depended on the aeration rate, and the highest fungal biomass obtained was 8.04 +/- 0.80 (g(biomass) (increase)/g(initial) (biomass)) at 1.5 vvm. The observed reductions in organic content by 80% (as soluble chemical oxygen demand) suggest the potential of recycling treated effluent as process water for in-plant use or for land applications. The fungal biomass contained similar to 50% crude protein and the essential amino acids contents were comparable to commercial protein sources for aquatic feeds (fishmeal and soybean meal), with the exception of methionine and phenylalanine. (C) 2013 Elsevier Ltd. All rights reserved.