Application of an encapsulated filamentous fungus in solubilization of inorganic phosphate.

Spores of Aspergillus niger were encapsulated in agar, calcium alginate and k-carrageenan and further applied in citric acid production during six repeated batch cultivations. Rock phosphate (RP) at concentrations of 3 g l-1 and 7 g l-1 was supplemented to the culture medium to test encapsulated-fungus solubilizing capability. The highest average citric acid productivity of 0.15 g l-1 h-1 was reached with alginate-bead-encapsulated A. niger on RP-free culture medium while agar seemed to be the most suitable carrier on RP-supplemented medium. Accordingly, the highest average soluble P concentration of 0.20 g l-1 batch-1 was obtained with agar-cell beads as compared with other encapsulated systems.