Mite growth on fungus under various environmental conditions and its potential application to biofilters.

The effects of relative humidity, temperature, pH and vapor-phase toluene concentration on Tyrophagus putrescentiae growth on Cladophialophora sp. were tested in controlled environmental chambers. It was observed that the mites were able to reproduce readily at relative humidities between 90% and 97% as well as on porous perlite support material pre-soaked in nutrient media of pH 2.

Dynamic bioreactor operation: Effects of packing material and mite predation on toluene removal from off-gas.

Recent studies have focused on using vapor-phase bioreactors for the treatment of volatile organic compounds from contaminated air streams. Although high removal capacities have been achieved in many studies, long-term operation is often unstable at high pollutant loadings due to biomass accumulation and drying of the packing medium. In this study, three bench-scale bioreactors were operated to determine the effect of packing material and fungal predation on toluene removal efficiency and pressure drop.

Performance of a styrene-degrading biofilter containing the yeast Exophiala jeanselmei.

A general mathematical model developed for a description of pollutant degradation in a biofilm was used to evaluate the performance of a biofilter for the purification of styrene-containing gas. The biofilter contained perlite as an inert support on which a biofilm was present composed of a mixed microbial population containing the fungus Exophiala jeanselmei as a major styrene-degrading microorganism. Although styrene is a moderately hydrophobic compound, the biofilter was reaction limited at a styrene gas phase concentration of 0.

Styrene metabolism in Exophiala jeanselmei and involvement of a cytochrome P-450-dependent styrene monooxygenase.

The yeast-like fungus Exophiala jeanselmei degrades styrene via initial oxidation of the vinyl side chain to phenylacetic acid, which is subsequently hydroxylated to homogentisic acid. The initial reactions are catalyzed by a NADPH- and flavin adenine dinucleotide-dependent styrene monooxygenase, a styrene oxide isomerase, and a NAD(+)-dependent phenylacetaldehyde dehydrogenase. The reduced CO-difference spectrum of microsomal preparations of styrene-grown cells shows a characteristic absorption maximum at 450 nm, which strongly suggests the involvement of a cytochrome P-450-dependent styrene monooxygenase.