Influence of perfluorocarbons on phanerochaete chrysosporium biomass development, substrate consumption and enzyme production

Abstract

Limitations placed on aerobic cultures by dissolved oxygen can be alleviated by using oxygen-vectors such as perfluorinated organic oils. In this study, Phanerochaete chrysosporium was tested in batch cultures to evaluate the efficacy of perfluorinated oils in improving biomass development, nutrient consumption and extracellular enzyme production. The oils used in an emulsified form in this study were perfluorotripropylamine, perfluorooctyl bromide and bis-(perfluorobutyl) ethene, as they dissolve higher quantities of oxygen compared to others. The surfactant used to stabilise the emulsion was Pluronic F 68, which was used at a concentration of 8.5 % (w/v). The addition of only the surfactant to the medium resulted in a 6.9-fold increase (1.38 mg mL–1) in biomass concentration of P. chrysosporium, while a biomass concentration of 0.82 to 1.53 mg mL–1 (4.1 to 7.6-fold increase) was observed in the PFC emulsions with an oil-phase fraction in the range of 0.1 to 0.3 (w/v), i.e. 10 to 30 % (w/v). The highest enzyme activity from crude samples was 307 and 410 U L–1 for LiP and MnP, respectively, compared to <100 and <50 U L–1 enzyme activity for LiP and MnP obtained in control cultures, respectively. Ammonium and glucose utilisation was higher in emulsions with PFC concentrations of 10 % (w/v) for all the perfluorocarbons evaluated than at concentrations of 20 % and 30 % (w/v). It was concluded that the use of the perfluorocarbon emulsions improved the performance of P. chrysosporium BKMF 1767 in terms of biomass development, nutrient consumption and enzyme production. Furthermore, PF 68 was found to have growth-promoting abilities for P. chrysosporium.