Animal Bone Char Solubilization with Itaconic Acid Produced by Free and Immobilized Aspergillus terreus Grown on Glycerol-Based Medium

Abstract

Cells of Aspergillus terreus, free and immobilized in polyurethane foam, were employed in itaconic acid fermentation processes on glycerol-based media. The purpose was to assess their suitability for animal bone char solubilization and the development of a biotechnological alternative to P fertilizers chemically produced from rock phosphate. Animal bones constitute a renewable source of P that can replace the traditionally used finite, nonrenewable rock phosphate as a P source. Glycerol was an excellent substrate for growth (10.2g biomass L(-1)) and itaconic acid production (26.9g L(-1)) by free fungal cells after 120-h fermentation. Simultaneously, A. terreus solubilized the insoluble phosphate to a yield of 23 to 50%, depending on the particle size and concentration. Polyurethane foam cut into cubes of 0.5-0.6cm per side, with 0.3mm pore size and applied at 2.0g L(-1) proved to be an excellent cell carrier. In repeated batch fermentation, the immobilized mycelium showed a high capacity to solubilize animal bone char, which resulted on average in 168.8mg L(-1) soluble phosphate per 48-h cycle and 59.4% yield (percent of total phosphate) registered in the fourth batch.