Citric acid production by Aspergillus niger from sugarcane bagasse with vinasse at different bed heights in packed-bed column

Solid-state cultivation (SSC) is the growth of microorganisms on solid supports in the absence or near absence of free water. Sugarcane bagasse and vinasse are generated abundantly in Brazil as byproducts from the ethanol industry, and bagasse has been used as solid matrix for SSC to produce a variety of bioproducts. The present study aimed to evaluate the SSC of Aspergillus niger on sugarcane bagasse impregnated with vinasse, with airflow rate and column bed height as scale-up criteria. Airflow rate of 0.8 L min-1 caused a citric acid productivity of 3.77 mg (L.h)-1 and a yield of 0.73 g g-1 at 100 mm bed height. On the other hand, an airflow rate of 3 L min-1 resulted in a productivity of 8.46 mg (L.h)-1 with 2.26 g g-1 of citric acid at 200 mm, and an estimated specific oxygen consumption rate of 0.008 mg per mg of biomass per hour.