A logistic model of subsurface fungal growth with application to bioremediation

The goal of this research was to determine the potential of the fungal sterol ergosterol as an indicator of fungal biomass and to determine the growth response of the transformed strain of T. virens (GvT6) to added substrate and changes in temperature. Experiments in liquid culture and agar plates containing a rich medium of glucose, yeast extract, and casein (GYEC), or a soil extract medium supplemented with maltose (SE) showed that the ergosterol content of GvT6 was greatest when grown on GYEC agar plates (14.02 mg/g dry biomass). For both media, plate cultures produced higher specific ergosterol values than liquid cultures. Changes in specific ergosterol values over time were generally not significant. A value of 5.41 mg ergosterol / g dry biomass, determined for SE plate cultures, was used to convert ergosterol values to biomass values in growth experiments in soil bioreactors. Data from experiments in soil bioreactors treated with different levels of substrate (0.5 - 8 mg maltose / g dry soil) at three different temperatures (22, 27, 32 degrees C) showed subsurface growth of GvT6 can be described by the logistic equation. Culture conditions of 32 degrees C and 8 mg/g substrate produced the highest levels of biomass, but growth at 32 degrees C and 4 mg/g substrate was somewhat faster than at the higher substrate level.