Determining the effect of organic carbon source on Se(IV) removal by common soil fungi

Abstract

The efficiency of Pyrenochaeta sp. in the transformation of bioavailable aqueous selenite [Se(IV)] to solid-associated Se or volatile Se(-II) was studied under different growth conditions. The removal of added 0.1mM Se(IV) was tracked over the course of 30 days for Pyrenochaeta cultures with access to 6 or 60 millimoles-C/L. Biomass weight was also measured for each of the 10 timepoints over the course of the experiment. Se(IV) was removed from solution under all conditions, though Pyrenochaeta seems to perform better with access to glucose: cultures without Se(IV) showed up to a 145% increase in biomass and cultures with Se(IV) showed up to a 58% removal of aqueous Se(IV) by the end of the 30 day period. Approximately 1.8% and 2.7% of Se(IV) was reduced to solid-phase Se in cultures with 3 and 30mM acetate, respectively. Experimental cultures with access to 1mM and 10mM glucose reduced 29.1% and 47.1% of aqueous Se(IV) to solid Se by the 30-day mark, respectively. We found that the form of organic carbon accessible to Pyrenochaeta does have an impact on their performance in reduction of Se(IV), though both glucose and acetate seem to facilitate reduction.