Selenium Recovery and Conversion by a Filamentous Fungus, Aspergillus oryzae Strain RIB40

A filamentous fungus (koji mold), Aspergillus oryzae strain RIB40 could be applied for selenium recovery and conversion. The granular cell-aggregates (mycelial cells) were able to reduce and convert selenite into nano-sized elemental selenium depositions when the granules were incubated under aerobic condition shaking at 120 rpm with a 100 ml baffled Erlenmeyer flask contained 20 ml of PD (potato dextrose) medium. In the aerobic condition, selenite (1 mM) was removed completely (over 99 %) from the culture within 24 hours by the mycelial cell-granules of strain RIB40. The cells turned red-orange due to the formation of elemental selenium nanospheres. Results of total selenium quantity determination in the red-orange coloured cellular granules by the atomic absorption method showed that most of selenite which disappeared from the culture were recovered to the granular cell-aggregates. These results demonstrate that a filamentous fungus, Aspergillus oryzae strain RIB40 can be used as an effective bio-material for recovery and reduction, and conversion of selenium-oxyanion in bioremediation, elemental resource recycling, biomineralization and biofabrication. Keywords — Aspergillus oryzae , Selenite reduction, Selenium recovery.