Methods to Increase Phenothiazine Conversion in Beauveria bassiana

Aims: The degradation of phenothiazine with the filamentous fungus Beauveria bassiana was studied under different fermentation conditions. The objective was to demonstrate methods to increase substrate conversion in wild type B. bassiana using phenothiazine as a screening substrate. A bio catalytic system was optimized to increase the conversion of phenothiazine by resting cell reactions.

Methodology and Results: Reactions were carried out with cells grown in different concentrations of glucose, 5 - 40 g/L, and different resting cell densities, 0.78-6.2 mg cdw/mL. The conversion was monitored with gas chromatography and was characterized by mass spectroscopy, chiral HPLC, and NMR. The highest conversion, 74%±1, was achieved with 0.78 mg cdw/mL. Glucose didn’t have an effect over the conversion of phenothiazine. This fungus oxidized phenothiazine into its sulfoxide and hydroxyl metabolites.

Conclusion: B. bassiana degrades more phenothiazine at lower cell densities than higher densities. The success of this project helps us expand the oxidation capacity of B. bassiana as a fungal biocatalyst while improving its utility for industrial purposes.